1. From: http://www.w3schools.com/sql
SQL
From:

2. SQL It is a standard language for accessing and manipulating databases
MySQL, SQL Server, Access, Oracle, Sybase, DB2, and others
SQL stands for Structured Query Language
SQL is an ANSI (American National Standards Institute) standard
There are many variations and different systems have their own extensions
But the major commands are same

3. SQL SQL include The query and update commands for DML
Data Manipulation Language (DML)
Data Definition Language (DDL)
The query and update commands for DML
SELECT: extracts data from a database
UPDATE: updates data in a database
DELETE: deletes data from a database
INSERT INTO: insert new data into a database
DDL: permits database tables to be created or deleted, define indexes (keys), impose constraints between tables. Some important statements:
CREATE DATABASE: creates a new database
ALTER DATABASE: modifies a database
CREATE TABLE: creates a new table
ALTER TABLE: modifies a table
DROP TABLE: deletes a table
CREATE INDEX: creates an index
DROP INDEX: deletes an index

4. Create Persons Table Persons Table P_Id LastName FirstName Address
City 1
Hansen
Ola
Timoteivn 10
Sandnes 2
Svendson
Tove
Borgvn 23 3
Pettersen
Kari
Storgt 20
Stavanger
CREATE DATABASE test;
CREATE TABLE persons (
P_Id INT,
LastName VARCHAR(25),
FirstName VARCHAR(25),
Address VARCHAR(25),
City VARCHAR(15),
PRIMARY KEY (P_Id) );
INSERT INTO persons VALUES (1, 'Hansen', 'Ola', 'Timoteivn10', 'Sandnes');
INSERT INTO persons VALUES (2, 'Svendson', 'Tove', 'Borgvn23','Sandnes');
INSERT INTO persons VALUES (3, 'Pettersen', 'Kari', 'Storgt20', 'Stavanger');

5. Aqua Data Studio
You can use either “go” or “/” to replace the “;” so that it can process multiple SQLs at the same time.
More info:
select * from t1 / select * from t2 / select * from t3 /
select * from t1 select * from t2 select * from t3
select * from t1 go select * from t2 go select * from t3 go

6. SQL Basic

7. SELECT SELECT is used to select data from a database
The result is stored in a result table, called the result-set
SQL is not case sensitive
SELECT syntax
SELECT column_name(s)
FROM table_name;
SELECT * FROM table_name;

8. SELECT Persons Table P_Id LastName FirstName Address City 1 Hansen Ola
Timoteivn 10
Sandnes 2
Svendson
Tove
Borgvn 23 3
Pettersen
Kari
Storgt 20
Stavanger
SELECT LastName, FirstName FROM Persons;
SELECT *FROM Persons;

9. SELECT DISTINCT SELECT DISTINCT column_name(s) FROM table_name;
SELECT DISTINCT city FROM persons;

10. WHERE clause SELECT column_name(s) FROM table_name
WHERE column_name operator value;
SELECT * FROM persons
WHERE city=‘Sandnes’;

11. WHERE Clause
Text values should be quoted by single quotes or double quotes
Numeric values do not need to be enclosed in quotes
SELECT * FROM persons
WHERE city=‘Sandnes’; Or
WHERE city=“Sandnes”;
WHERE P_Id=1;

12. WHERE Clause Description Operator Equal = Not equal <>
Greater than
<
Less than
>=
Greater than or equal
<=
Less than or equal
BETWEEN
Between an inclusive range
LIKE
Search for a pattern IN
If you know the exact value you want to return for at least one of the columns

13. AND or OR
AND, OR operators are used to filter records based on more than one condition
AND=both the first and the second conditions is true
OR=either the first or the second condition is true

14. AND or OR SELECT * FROM persons
WHERE firstname=‘Tove’ AND lastname=‘Svendson’;
SELECT * FROM persons
WHERE firstname=‘Tove’ OR firstname=‘Ola’;
SELECT * FROM persons
WHERE lastname=‘Svendson’ AND (firstname=‘Tove’ OR firstname=‘Ola’);

15. ORDER BY
The ORDER BY keyword is used to sort the result-set by a specified column
It sorts the records in ascending order by default
Use DESC for a descending order
SELECT column_name(s)
FROM table_name
ORDER BY column_name(s) ASC|DESC;

16. ORDER BY
INSERT INTO persons VALUES (4, ‘Nilsen’, ‘Tom’, ‘Vingvn23', 'Stavanger');
SELECT * FROM Persons
ORDER BY lastname;
SELECT * FROM Persons
ORDER BY lastname DESC;

17. INSERT INTO Use to insert new records in a table
INSERT INTO table_name
VALUES (value1, value2, value3,…);
INSERT INTO table_name (column1, column2, column3, …
VALUES (value1, value2, value3,…);
INSERT INTO persons VALUES (4, ‘Nilsen’, ‘Tom’, ‘Vingvn23', 'Stavanger');
INSERT INTO persons (P_Id, lastname, firstname)
VALUES (5, ‘Tjessem’, ‘Jakob’);

18. UPDATE Update records in a table UPDATE table_name
SET column=value, column2=value2,…
WHERE some_column=some_value;
UPDATE Persons
SET Address=‘Nissestien 67’, city=‘Sandnes’
WHERE lastname=‘Tjessem’ AND firstname=‘Jakob’;
Warning: if you forget to add WHERE clause, all the address and city will be set to ‘Nissestien 67’ and ‘Sandnes’.

19. DELETE statement Used to delete records in a table
DELETE FROM table_name
WHERE some_column=some_value;
DELETE FROM persons
WHERE lastname=‘Tjessem’ AND firstname=‘Jakob’;
DELETE FROM table_name; Or
DELETE * FROM table_name;

20. Test Create this Customers table and do the following SQL queries
CompanyName
ContactName
Address
City
Alfreds Futterkiste 
Maria Anders 
Obere Str. 57 
Berlin 
Berglunds snabbköp 
Christina Berglund 
Berguvsvägen 8 
Luleå 
Centro comercial Moctezuma 
Francisco Chang 
Sierras de Granada 9993 
México D.F. 
Ernst Handel 
Roland Mendel 
Kirchgasse 6 
Graz 
FISSA Fabrica Inter. Salchichas S.A. 
Diego Roel 
C/ Moralzarzal, 86 
Madrid 
Galería del gastrónomo 
Eduardo Saavedra 
Rambla de Cataluña, 23 
Barcelona 
Island Trading 
Helen Bennett 
Garden House Crowther Way 
Cowes 
Königlich Essen 
Philip Cramer 
Maubelstr. 90 
Brandenburg 
Laughing Bacchus Wine Cellars 
Yoshi Tannamuri 
1900 Oak St. 
Vancouver 
Magazzini Alimentari Riuniti 
Giovanni Rovelli 
Via Ludovico il Moro 22 
Bergamo 
North/South 
Simon Crowther 
South House 300 Queensbridge 
London 
Paris spécialités 
Marie Bertrand 
265, boulevard Charonne 
Paris 
Rattlesnake Canyon Grocery 
Paula Wilson 
2817 Milton Dr. 
Albuquerque 
Simons bistro 
Jytte Petersen 
Vinbæltet 34 
København 
The Big Cheese 
Liz Nixon 
89 Jefferson Way Suite 2 
Portland 
Vaffeljernet 
Palle Ibsen 
Smagsløget 45 
Århus 
Wolski Zajazd 
Zbyszek Piestrzeniewicz 
ul. Filtrowa 68 
Warszawa 
Create this Customers table and do the following SQL queries

21. TEST CREATE TABLE customers ( CompanyName VARCHAR(100),
ContactName VARCHAR(100),
Address VARCHAR(100),
City VARCHAR(50) );
INSERT INTO customers VALUES ('Alfreds Futterkiste', 'Maria Anders', 'Obere Str. 57', 'Berlin');
INSERT INTO customers VALUES ('Berglunds snabbköp', 'Christina Berglund', 'Berguvsvägen 8','Luleå');
INSERT INTO customers VALUES ('Centro comercial Moctezuma', 'Francisco Chang', 'Sierras de Granada 9993', 'México D.F.');
INSERT INTO customers VALUES ('Ernst Handel', 'Roland Mendel', 'Kirchgasse 6', 'Graz');
INSERT INTO customers VALUES ('FISSA Fabrica Inter. Salchichas S.A.', 'Diego Roel', 'C/Moralzarzal, 86 ', 'Madrid');
INSERT INTO customers VALUES ('Galería del gastrónomo', 'Eduardo Saavedra', 'Rambla de Cataluña, 23', 'Barcelona');
INSERT INTO customers VALUES ('Island Trading', 'Helen Bennett', 'Garden House Crowther Way', 'Cowes');
INSERT INTO customers VALUES ('Königlich Essen', 'Philip Cramer', 'Maubelstr. 90', 'Brandenburg');
INSERT INTO customers VALUES ('Laughing Bacchus Wine Cellars', 'Yoshi Tannamuri', '1900 Oak St.', 'Vancouver');
INSERT INTO customers VALUES ('Magazzini Alimentari Riuniti', 'Giovanni Rovelli', 'Via Ludovico il Moro 22', 'Bergamo');
INSERT INTO customers VALUES ('North/South', 'Simon Crowther', 'South House 300 Queensbridge', 'London');
INSERT INTO customers VALUES ('Paris spécialités', 'Marie Bertrand', '265, boulevard Charonne', 'Paris');
INSERT INTO customers VALUES ('Rattlesnake Canyon Grocery', 'Paula Wilson', '2817 Milton Dr.', 'Albuquerque');
INSERT INTO customers VALUES ('Simons bistro', 'Jytte Petersen', 'Vinbæltet 34', 'København');
INSERT INTO customers VALUES ('The Big Cheese', 'Liz Nixon', '89 Jefferson Way Suite 2', 'Portland');
INSERT INTO customers VALUES ('Vaffeljernet', 'Palle Ibsen', 'Smagsløget 45', 'Århus');
INSERT INTO customers VALUES ('Wolski Zajazd', 'Zbyszek Piestrzeniewicz', 'ul. Filtrowa 68', 'Warszawa');

22. TEST SELEC * FROM customers;
SELECT CompanyName, ContactName FROM customers;
SELECT * FROM customers WHERE companyname LIKE ‘a%’;
SELECT * FROM customers WHERE companyname LIKE ‘A%’;
SELECT companyname, contactname
FROM customers
WHERE companyname > ‘A’;
WHERE companyname > ‘G’
AND contactname > ‘G’;

23. SQL Advanced

24. LIMIT clause Used to specify the number of records to return
SELECT column_name(s)
FROM table_name
LIMIT number;
SELECT * FROM persons LIMIT 2;
Oracle, SQL Server: Top number|percent (e.g., Top 2, or Top 50 PERCENT
Oracle: ROWNUM<=number (e.g., ROWNUM<=5)

25. LIKE operator
Used in a WHERE clause to search for a specified pattern in a column
SELECT column_name(s)
FROM table_name
WHERE column_name LIKE pattern;
SELECT * FROM persons WHERE city LIKE ‘S%’;
%: define wildcards (missing letters) both before and after the pattern
SELECT * FROM persons WHERE city LIKE ‘%s’;

26. SQL Wildcards
SQL Wildcards can substitute for one or more characters when searching for data in a database
SQL wildcards must be used with the SQL LIKE operator
Wildcard
Description %
A substitute for zero or more characters _
A substitute for exactly one character

27. SQL Wildcards SELECT * FROM persons WHERE city LIKE ‘Sa%’;
SELECT * FROM persons WHERE city LIKE ‘%nes%’;
SELECT * FROM persons WHERE firstname LIKE ‘_la’;
SELECT * FROM persons WHERE lastname LIKE ‘S_end_on’;

28. IN operator To specify multiple values in a WHERE clause
SELECT column_name(s)
FROM table_name
WHERE column_name IN (value1, value2,…)
SELECT * FROM Persons
WHERE lastname IN (‘Hansen’, ‘Pettersen’)
SELECT * FROM Persons
WHERE lastname IN (SELECT lastname from Persons where city=‘Sandnes’)

29. BETWEEN operator
Used in a WHERE clause to select a range of data between two values
SELECT column_name(s)
FROM table_name
WHERE column_name BETWEEN value1 AND value 2;
SELECT * FROM persons
WHERE lastname BETWEEN ‘Hansen’ AND ‘Pettersen’;
Warning: different database systems have different ways of processing BETWEEN operator
SELECT * FROM persons
WHERE lastname NOT BETWEEN ‘Hansen’ AND ‘Pettersen’;

30. Alias An alias name can be given to a table or a column
SELECT column_name(s)
FROM table_name AS alias_name; Or
SELECT column_name AS alias_name
FROM table_name;
SELECT po.O_ID, p.LastName, p.FirstName
FROM Persons AS p, Orders AS po
WHERE p.LastName='Hansen' AND p.FirstName='Ola';
Without alias
SELECT Orders.OrderID, Persons.LastName, Persons.FirstName
FROM Persons, Orders
WHERE Persons.LastName=‘Hansen’ AND Persons.FirstName=‘Ola’;

31. JOIN Used to query data from two or more tables
JOIN: return rows when there is at least one match in both tables
LEFT JOIN: return all rows from the left table, even if there are no matches in the right table
RIGHT JOIN: return all rows from the right table, even if there are no matches in the left table
FULL JOIN: return rows where there is a match in one of the tables

32. JOIN
O_Id
OrderNo
P_Id 1
77895 3 2
44678
22456 4
24562 5
34764 15
CREATE DATABASE test;
CREATE TABLE orders (
O_Id INT,
OrderNO INT,
P_Id INT,
PRIMARY KEY (O_Id) );
INSERT INTO orders VALUES (1, 77895, 3);
INSERT INTO orders VALUES (2, 44678, 3);
INSERT INTO orders VALUES (3, 22456, 1);
INSERT INTO orders VALUES (4, 24562, 1);
INSERT INTO orders VALUES (5, 34764, 15);
Same as INNER JOIN

33. INNER JOIN SELECT column_name(s)
FROM table_name1 INNER JOIN table_name2
ON table_name1.column_name=table_name2.column_name;
SELECT persons.lastname, persons.firstname, orders.orderNo
From Persons INNER JOIN Orders
ON persons.P_Id=orders.P_Id
ORDER BY persons.Lastname;
The INNER JOIN keyword returns rows where there is at least one match in both tables. If there are rows in Persons that do not have matches in Orders, those rows will NOT be listed.

34. LEFT JOIN
Returns all rows from the left table, even if there are no matches in the right table
SELECT column_name(s)
FROM table_name1 LEFT JOIN table_name2
ON table_name1.column_name=table_name2.column_name;
In some databases, LEFT JOIN is called LEFT OUTER JOIN
SELECT persons.lastname, persons.firstname, orders.orderno
FROM persons LEFT JOIN orders
ON persons.P_Id=orders.P_Id
ORDER BY persons.lastname;

35. RIGHT JOIN SELECT column_name(s)
Returns all rows from the right table (table 2), even if there are no matches in the left table (table 1)
SELECT column_name(s)
FROM table_name1 RIGHT JOIN table_name2
ON table_name1.column_name=table_name2.column_name;
In some databases, RIGHT JOIN is called RIGHT OUTER JOIN
SELECT persons.lastname, persons.firstname, orders.orderno
FROM persons RIGHT JOIN orders
ON persons.P_Id=orders.P_Id
ORDER BY persons.lastname;

36. FULL JOIN Return rows when there is a match in one of the tables
SELECT column_name(s)
FROM table_name1 FULL JOIN table_name2
ON table_name1.column_name=table_name2.column_name;
FULL JOIN is not supported by MySQL.
FULL JOIN = LEFT JOIN UNION
RIGHT JOIN
SELECT persons.lastname, persons.firstname, orders.orderno
FROM persons FULL JOIN orders
ON persons.P_Id=orders.P_Id
ORDER BY persons.lastname;
SELECT persons.lastname, persons.firstname, orders.orderno
FROM persons LEFT JOIN orders
ON persons.P_Id=orders.P_Id
UNION
FROM persons RIGHT JOIN orders

37. UNION operator Combines two or more SELECT statements
Each SELECT statement must have the same columns (same name, same data types, in the same order)
UNION selects only distinct values by default. To allow duplicate values, use UNION ALL.
SELECT column_name(s) FROM table_name1
UNION
SELECT column_name(s) FROM table_name2;
SELECT column_name(s) FROM table_name1
UNION ALL
SELECT column_name(s) FROM table_name2;
SELECT P_Id FROM persons
UNION
SELECT P_Id FROM orders;

38. CREATE DATABASE Used to create a database
CREATE DATABASE database_name;
CREATE DATABASE my_db;

39. CREATE TABLE Used to create a table within a database
CREATE TABLE table_name
(column_name1 data_type,
column_name2 data_type,
column_name3 data_type,
….);
CREATE TABLE persons (
P_Id INT,
LastName VARCHAR(25),
FirstName VARCHAR(25),
Address VARCHAR(25),
City VARCHAR(15),
PRIMARY KEY (P_Id) );

40. Constraints NOT NULL UNIQUE PRIMARY KEY FOREIGN KEY CHECK DEFAULT
Used to limit the type of data that can go into a table
Can be specified when a table is created (with the CREATE TABLE statement) or after the table is created (with the ALTER TABLE statement)
Type of constraints:
NOT NULL
UNIQUE
PRIMARY KEY
FOREIGN KEY
CHECK
DEFAULT

41. NOT NULL Enforce a column to not accept NULL values
CREATE TABLE Persons (
P_Id INT NOT NULL,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Address varchar(255),
City varchar(255) );

42. UNIQUE Uniquely identifies each record in a database table
UNIQUE and PRIMARY KEY both provide a guarantee for uniqueness for a column or set of columns
A PRIMARY KEY constraint automatically has a UNIQUE constraint defined on it.

43. UNIQUE CREATE TABLE Persons ( P_Id INT NOT NULL,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Address varchar(255),
City varchar(255)
UNIQUE (P_Id) );
CREATE TABLE Persons (
P_Id INT NOT NULL UNIQUE,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Address varchar(255),
City varchar(255) );
MySQL
SQL Server/Oracle/MS Access
CREATE TABLE Persons (
P_Id INT NOT NULL,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Address varchar(255),
City varchar(255)
CONSTRAINT uc_PersonID UNIQUE (P_Id, LastName) );
MySQL/SQL Server/Oracle/MS Access

44. UNIQUE
When Persons table has already been created, use Alter to add new constraints.
ALTER TABLE Persons
ADD UNIQUE (P_Id)
ALTER TABLE Persons
ADD CONSTRAINT un_PersonID UNIQUE (P_Id, LastName)
To drop a UNIQUE constraint
ALTER TABLE Persons
DROP INDEX un_PersonID
MySQL
ALTER TABLE Persons
DROP CONSTRAINT un_PersonID
SQL Server/Oracle/MS Access

45. PRIMARY KEY Each table should have one and only one primary key
Primary key should be unique and does not contain NULL values
CREATE TABLE Persons (
P_Id INT NOT NULL,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Address varchar(255),
City varchar(255)
PRIMARY KEY (P_Id) );
CREATE TABLE Persons (
P_Id INT NOT NULL PRIMARY KEY,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Address varchar(255),
City varchar(255) );
SQL Server/Oracle/MS Access
MySQL
CREATE TABLE Persons
( P_Id INT NOT NULL,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Address varchar(255),
City varchar(255)
CONSTRAINT pk_PersonID PRIMARY KEY (P_Id, LastName) );
MySQL/SQL Server/Oracle/MS Access

46. PRIMARY KEY
When Persons table has already been created, use Alter to add new constraints.
ALTER TABLE Persons
ADD PRIMARY KEY (P_Id)
ALTER TABLE Persons
ADD CONSTRAINT un_PersonID PRIMARY KEY (P_Id, LastName)
To drop a constraint
ALTER TABLE Persons
DROP PRIMARY KEY
MySQL
ALTER TABLE Persons
DROP CONSTRAINT pk_PersonID
SQL Server/Oracle/MS Access

47. FOREIGN KEY CREATE TABLE Orders ( O_Id INT NOT NULL,
A foreign key in one table points to a primary key in another table
The foreign key constraint prevents invalid data from being inserted into the foreign key column because it has to be one of the values contained in the table it points to.
CREATE TABLE Orders (
O_Id INT NOT NULL,
OrderNo INT NOT NULL,
P_Id INT,
PRIMARY KEY (O_Id),
FOREIGN KEY (P_Id) REFERENCES Persons (P_Id) );
CREATE TABLE Orders (
O_Id INT NOT NULL PRIMARY KEY,
OrderNo INT NOT NULL,
P_Id INT FOREIGN KEY REFERENCES Persons(P_Id) );
SQL Server/Oracle/MS Access
MySQL
CREATE TABLE Orders
( O_Id INT NOT NULL,
OrderNo INT NOT NULL,
P_Id INT,
PRIMARY KEY (O_Id),
CONSTRAINT fk_PerOrders FOREIGN KEY (P_Id) REFERENCES Persons (P_Id));
MySQL/SQL Server/Oracle/MS Access

48. FOREIGN KEY
When Orders table has already been created, use Alter to add new constraints.
ALTER TABLE Orders
ADD CONSTRAINT fk_PerOrders
FOREIGN KEY (P_Id)
REFERENCES Persons(P_Id)
ALTER TABLE Orders
ADD FOREIGN KEY (P_Id)
REFERENCES Persons (P_Id)
To drop a constraint
MySQL
ALTER TABLE Orders
DROP FOREIGN KEY fk_PerOrders
ALTER TABLE Orders
DROP CONSTRAINT fk_PerOrders
SQL Server/Oracle/MS Access

49. CHECK Constraint Used to limit the value range of a column
CREATE TABLE Persons ( P_Id int NOT NULL, LastName varchar(255) NOT NULL, FirstName varchar(255), Address varchar(255), City varchar(255), CHECK (P_Id>0) )
CREATE TABLE Persons ( P_Id int NOT NULL CHECK (P_Id>0), LastName varchar(255) NOT NULL, FirstName varchar(255), Address varchar(255), City varchar(255) )
SQL Server/Oracle/MS Access
MySQL
CREATE TABLE Persons (P_Id int NOT NULL, LastName varchar(255) NOT NULL, FirstName varchar(255), Address varchar(255), City varchar(255), CONSTRAINT chk_Person CHECK (P_Id>0 AND City='Sandnes‘));
MySQL/SQL Server/Oracle/MS Access

50. CHECK Constraint
When a table has already been created, use Alter to add new constraints.
ALTER TABLE Persons
ADD CONSTRAINT chk_Person
CHECK (P_Id>0 AND City=‘Sandnes’)
ALTER TABLE Persons
ADD CHECK (P_Id>0)
To drop a constraint
SQL Server/Oracle/MS Access
ALTER TABLE Persons
DROP CONSTRAINT chk_Person

51. DEFAULT Constraint Used to insert a default value into a column
CREATE TABLE Persons ( P_Id int NOT NULL, LastName varchar(255) NOT NULL, FirstName varchar(255), Address varchar(255), City varchar(255) DEFAULT 'Sandnes' )
CREATE TABLE Orders ( O_Id int NOT NULL, OrderNo int NOT NULL, P_Id int, OrderDate date DEFAULT GETDATE() )
MySQL/SQL Server/Oracle/MS Access
MySQL/SQL Server/Oracle/MS Access

52. DEFAULT Constrain
When a table has already been created, use Alter to add new constraints.
ALTER TABLE Persons
ALTER COLUMN City SET DEFAULT ‘Sandnes’
ALTER TABLE Persons
ALTER City SET DEFAULT ‘Sandnes’
MySQL
SQL Server/Oracle/MS Access
To drop a constraint
MySQL
ALTER TABLE Persons
ALTER City DROP DEFAULT
ALTER TABLE Persons
ALTER COLUMN City DROP DEFAULT
SQL Server/Oracle/MS Access

53. CREATE INDEX statement
An index can be created in a table to find data more quickly and efficiently.
The users cannot see the indexes.
Indexes can speed up searches/queries
Updating a table with indexes takes more time than updating a table without indexes. Because indexes also need to update.
So please create indexes on columns (and tables) that will be frequently searched.

54. CREATE INDEX statement
CREATE INDEX index_name
ON table_name (column_name)
Duplicate values are allowed
CREATE UNIQUE INDEX index_name
ON table_name (column_name)
Duplicate values are not allowed
CREATE INDEX PIndex
ON Persons (lastname)
CREATE INDEX PIndex
ON Persons (LastName, FirstName)

55. SQL DROP INDEX, DROP TABLE, DROP DATABASE
MS Access
DROP INDEX index_name ON table_name
DROP INDEX table_name.index_name
MS SQL Server
DROP INDEX index_name
DB2/Oracle
ALTER TABLE table_name DROP INDEX index_name
MySQL
DROP TABLE table_name
DROP DATABASE database_name
TRUNCATE TABLE table_name
Delete data inside the table, not the table itself

56. SQL ALTER TABLE statement
Alter table statement is used to add, delete, or modify columns in an existing table
ALTER TABLE table_name
ADD column_name datatype
To add a column in a table
ALTER TABLE table_name
DROP COLUMN column_name
To delete a column in a table (some database systems don’t allow deleting a column)
ALTER TABLE table_name
ALTER COLUMN column_name datatype
To change the data type of a column in a table

57. SQL ALTER TABLE statement
ALTER TABLE Persons
ADD DateOfBirth date
ALTER TABLE Persons
DROP COLUMN DateOfBirth

58. SQL AUTO INCREMENT
Auto-increment allows a unique number to be generated when a new record is inserted into a table
MySQL
CREATE TABLE Persons ( P_Id int NOT NULL AUTO_INCREMENT, LastName varchar(255) NOT NULL, FirstName varchar(255), Address varchar(255), City varchar(255), PRIMARY KEY (P_Id) )
ALTER TABLE Persons AUTO_INCREMENT=100
To start the auto_increment with another value
INSERT INTO Persons (FirstName, LastName) VALUES (‘Lars’, ‘Monsen’)

59. SQL AUTO INCREMENT
Auto-increment allows a unique number to be generated when a new record is inserted into a table
SQL Server
CREATE TABLE Persons ( P_Id int PRIMARY KEY IDENTITY, LastName varchar(255) NOT NULL, FirstName varchar(255), Address varchar(255), City varchar(255) )
ALTER TABLE Persons AUTO_INCREMENT=100
To start the auto_increment with another value
INSERT INTO Persons (FirstName, LastName) VALUES (‘Lars’, ‘Monsen’)
To start at 10 and increment by 5 IDENTITY(10,5)

60. SQL AUTO INCREMENT
Auto-increment allows a unique number to be generated when a new record is inserted into a table
Access
CREATE TABLE Persons ( P_Id PRIMARY KEY AUTOINCREMENT, LastName varchar(255) NOT NULL, FirstName varchar(255), Address varchar(255), City varchar(255) )
INSERT INTO Persons (FirstName, LastName) VALUES (‘Lars’, ‘Monsen’)
To start at 10 and increment by 5 AUTOINCREMENT(10,5)

61. SQL AUTO INCREMENT
Auto-increment allows a unique number to be generated when a new record is inserted into a table
Oracle
CREATE SEQUENCE seq_person MINVALUE 1 START WITH 1 INCREMENT BY 1 CACHE 10
INSERT INTO Persons (P_Id,FirstName,LastName) VALUES (seq_person.nextval,'Lars','Monsen')
To start at 10 and increment by 5 AUTOINCREMENT(10,5)

62. SQL Views
A view is a virtual table based on the result-set of an SQL statement
A view just looks like a real table with fields and records from one or more real tables in the database
CREATE VIEW view_name AS
SELECT column_name(s)
FROM table_name
WHERE condition
CREATE VIEW Sandnes AS
SELECT LastName, FirstName
FROM Persons
WHERE city=‘Sandnes’
CREATE VIEW SandnesLastName AS
SELECT LastName
FROM Sandnes
SELECT * FROM SandnesLastName
SELECT * FROM Sandnes

63. SQL Views A view can be updated or dropped
CREATE OR REPLACE OR ALTER VIEW view_name AS
SELECT column_name(s)
FROM table_name
WHERE condition
ALTER VIEW Sandnes AS
SELECT LastName, FirstName, Address
FROM Persons
WHERE city=‘Sandnes’
DROP VIEW view_name
SELECT * FROM Sandnes
DROP VIEW Sandnes

64. SQL Functions

65. SQL Functions
SQL Aggregate functions: return a single value calculated from values in a column
AVG() – Returns the average value
COUNT() – Returns the number of rows
FIRST() – Returns the first value
LAST() – Returns the last value
MAX() – Returns the largest value
MIN() – Returns the smallest value
SUM() – Returns the sum

66. SQL Functions
SQL Scalar functions: returns a single value based on the input value
UCASE() – Converts a field to upper case
LCASE() – Converts a field to lower case
MID() – Extracts characters from a text field
LEN() – Returns the length of a text field
ROUND() – Rounds a numeric field to the number of decimals specified
NOW() – Returns the current system date and time
FORMAT() – Formats how a field is to be displayed

67. Create Products Table Persons Table P_Id ProductName UnitPrice
UnitsInStock
UnitsOnOrder 1
Jarlsberg
10.45 16 15 2
Mascarpone
32.56 23 3
Gorgonzola
15.67 9 20
CREATE TABLE products (
P_Id INT,
ProductName VARCHAR(25),
UnitPrice decimal,
UnitsInStock INT,
UnitsOnOrder INT,
PRIMARY KEY (P_Id) );
INSERT INTO products VALUES (1, ‘Jarlsberg', 10.45, 16, 15);
INSERT INTO products VALUES (2, ‘Mascarpone', 32.56, 23,NULL);
INSERT INTO products VALUES (3, ‘Gorgonzola', 15.67, 9, 20);

68. SQL AVG() Function AVG() returns the average value of a numeric column
SELECT AVG(column_name) FROM table_name
SELECT AVG(UnitPrice) AS UnitAverage FROM Products
SELECT ProductName FROM products
WHERE UnitPrice>( SELECT AVG(UnitPrice) FROM Products)

69. SQL COUNT() Function
COUNT() returns the number of rows that matches a specified criteria
SELECT COUNT(column_name) FROM table_name
SELECT COUNT(*) FROM Products
SELECT COUNT(DISTINCT column_name) FROM table_name
SELECT COUNT(DISTINCT city) As CityName From persons

70. SQL MAX() Function
MAX() returns the largest value of the selected column
SELECT MAX(column_name) FROM table_name
SELECT MAX(UnitPrice) AS LargestUnitPrice FROM Products

71. SQL SUM() Function SUM() returns the total sum of the selected column
SELECT SUM(column_name) FROM table_name
SELECT SUM(UnitPrice) AS TotalUnitPrice FROM Products

72. Create CumOrders Table
O_Id
OrderDate
OrderPrice
Customer 1
2008/11/12
1000
Hansen 2
2008/10/23
1600
Nilsen 3
2008/09/02
700 4
2008/09/03
300 5
2008/08/30
2000
Jensen 6
2008/10/04
100
CREATE TABLE CumOrders (
O_Id INT,
OrderDate Date,
OrderPrice INT,
Customer Varchar(30),
PRIMARY KEY (O_Id) );
INSERT INTO cumorders VALUES (1, ‘ ’, 1000, ‘Hansen’);
INSERT INTO cumorders VALUES (2, ‘ ’, 1600, ‘Nilsen’);
INSERT INTO cumorders VALUES (3, ‘ ’, 700, ‘Hansen’);
INSERT INTO cumorders VALUES (4, ‘ ’, 300, ‘Hansen’);
INSERT INTO cumorders VALUES (5, ‘ ’, 2000, ‘Jensen’);
INSERT INTO cumorders VALUES (6, ‘ ’, 100, ‘Nilsen’);

73. SQL GROUP BY Statement
Aggregate functions often need an added GROUP BY statement to group the result-set by one or more columns
SELECT column_name, aggregate_function(column_name)
FROM table_name
WHERE column_name operator value
GROUP BY column_name
SELECT Customer, SUM(OrderPrice) FROM CumOrders
GROUP BY Customer
SELECT Customer, OrderDate, SUM(OrderPrice) FROM CumOrders
GROUP BY Customer, OrderDate

74. SQL HAVING Clause
HAVING was added to SQL because the WHERE keyword could not be used wit the aggregate functions
SELECT column_name, aggregate_function(column_name)
FROM table_name
WHERE column_name operator value
GROUP BY column_name
HAVING aggregate_function(column_name) operator value
SELECT Customer, SUM(OrderPrice) FROM CumOrders
GROUP BY Customer
HAVING SUM(OrderPrice)<2000

75. SQL HAVING Clause SELECT Customer, SUM(OrderPrice) FROM CumOrders
WHERE Customer=‘Hansen’ OR Customer=‘Jensen’
GROUP BY Customer
HAVING SUM(OrderPrice)>1500

76. SQL UCASE() Function
UCASE() converts the value of a field to uppercase.
SELECT UCASE(column_name) FROM table_name
SELECT UCASE(LastName) as LastName From Persons

77. SQL LCASE() Function
LCASE() converts the value of a field to lowercase.
SELECT LCASE(column_name) FROM table_name
SELECT LCASE(LastName) as LastName From Persons

78. SQL MID() Function MID() extracts characters from a text field
SELECT MID(column_name, start[, length]) FROM table_name
Parameter
Description
column_name
Required. The field to extract characters from
start
Required. Specifies the starting position (starts at 1)
length
Optional. The number of characters to return. If omitted, the MID() function returns the rest of the text
SELECT MID(City, 1, 4) as SmallCity From Persons
MySQL
SELECT substr(City, 1, 4) as SmallCity From Persons
PostgreSQL
PostgreSQL:

79. SQL LENGTH() Function
LENGTH() returns the length of the value in a text field.
SELECT LENGTH(column_name) FROM table_name
SELECT LENGTH(Address) as LengthOfAddress From Persons

80. SQL ROUND() Function
ROUND() rounds a numeric field to the number of decimals specified
SELECT ROUND(column_name, decimals) FROM table_name
Parameter
Description
column_name
Required. The field to round.
decimals
Required. Specifies the number of decimals to be returned.
UPDATE Products
SET UnitPrice=10.49
WHERE P_Id=1
SELECT ROUND(UnitPrice, 0) as Price From Products

81. SQL Date Functions
Introduces some build-in functions to deal with dates
MySQL Date Functions
Function
Description
NOW()
Returns the current date and time
CURDATE()
Returns the current date
CURTIME()
Returns the current time
DATE()
Extracts the date part of a date or date/time expression
EXTRACT()
Returns a single part of a date/time
DATE_ADD()
Adds a specified time interval to a date
DATE_SUB()
Subtracts a specified time interval from a date
DATEDIFF()
Returns the number of days between two dates
DATE_FORMAT()
Displays date/time data in different formats
PostgreSQL:

82. MySQL NOW() Function NOW() returns the current date and time
SELECT NOW()
SELECT NOW(), CURDATE(), CURTIME()
MySQL
PostgreSQL
CREATE TABLE Orders ( OrderId int NOT NULL, ProductName varchar(50) NOT NULL, OrderDate datetime NOT NULL, PRIMARY KEY (OrderId) )
INSERT INTO orders VALUES (1, ‘Jarlsberg Cheese’, NOW())
SELECT ProductName, UnitPrice, NOW() as PerDate FROM Products

83. MySQL CURDATE() Function
CURDATE() returns the current date
SELECT NOW(), CURDATE(), CURTIME()
CREATE TABLE Orders ( OrderId int NOT NULL, ProductName varchar(50) NOT NULL, OrderDate datetime NOT NULL, PRIMARY KEY (OrderId) )
INSERT INTO orders VALUES (2, ‘Jarlsberg Cheese’, CURDATE())

84. MySQL DATE() Function
DATE() function extracts the date part of a date or date/time expression
DATE(date)
SELECT ProductName, DATE(OrderDate) as OrderDate
FROM Orders
WHERE OrderId=1

85. MySQL EXTRACT() Function
The EXTRACT() function returns a single part of a date/time, such as year, month, day, hour, minute, etc.
Unit value can be: SECOND, MINUTE, HOUR, DAY, WEEK, MONTH, QUARTER, YEAR, or any combination of them
EXTRACT(unit FROM date)
SELECT EXTRACT(YEAR FROM OrderDate) as OrderYear,
EXTRACT(Month FROM OrderDate) as OrderMonth,
EXTRACT(DAY FROM OrderDate) as OrderDay
FROM Orders
WHERE OrderID=1

86. MySQL DATE_ADD() Function
The DATE_ADD() function adds a specified time interval to a date.
DATE_ADD(date, INTERVAL expr type)
SELECT OrderID, DATE_ADD(OrderDate, INTERVAL 45 DAY) AS OrderPayDate
FROM Orders

87. MySQL DATE_SUB() Function
The DATE_SUB() function subtracts a specified time interval from a date.
DATE_SUB(date, INTERVAL expr type)
SELECT OrderID, DATE_SUB(OrderDate, INTERVAL 5 DAY) AS SubtractDate
FROM Orders

88. MySQL DATEIFF() Function
The DATEDIFF() function returns the time between two dates.
DATEDIFF(date1, date2)
SELECT DATEDIFF ( ‘ ’, ‘ ’) AS DiffDate

89. MySQL DATE_FORMAT() Function
The DATE_FORMAT() function displays the date/time in different formats.
DATE_FORMAT(date, format)
SELECT DATE_FORMAT(NOW(), ‘%m-%d-%y’)

90. SQL Date Functions
Introduces some build-in functions to deal with dates
SQL Server Date Functions
Function
Description
GETDATE()
Returns the current date and time
DATEPART()
Returns a single part of a date/time
DATEADD()
Adds or subtracts a specified time interval from a date
DATEDIFF()
Returns the time between two dates
CONVERT()
Displays date/time data in different formats

91. SQL Date Datatypes MySQL Date: YYYY-MM-DD
Datetime: YYYY-MM-DD HH:MM:SS
Timestamp: YYYY-MM-DD HH:MM:SS
Year: YYYY or YY
SELECT * FROM Orders WHERE OrderDate=‘ ’

92. SQL NULL Values NULL values represent missing unknown data.
NULL is used as a placeholder for unknown or inapplicable values
NULL vs. 0
INSERT INTO persons VALUES (5, 'Ding', 'Ying', NULL, NULL);
SELECT * FROM Persons
WHERE Address IS NULL
SELECT * FROM Persons
WHERE Address IS NOT NULL
DELETE FROM Persons WHERE P_ID=5

93. SQL NULL Functions
SELECT ProdcutName, UnitPrice*(UnitsInStock+UnitsOnOrder)
FROM Products
ISNULL(), NVL(), IFNULL(), COALESCE() are used to treat NULL values.
Below all makes nulls to be zero
SELECT ProductName, UnitPrice*(UnitsInStock+ISNULL(UnitsOnOrder,0))
FROM Products
SQL Server/Access
SELECT ProductName, UnitPrice*(UnitsInStock+NVL(UnitsOnOrder,0))
FROM Products
Oracle
SELECT ProductName, UnitPrice*(UnitsInStock+IFNULL(UnitsOnOrder,0)) AS Price
FROM Products
MySQL
SELECT ProductName, UnitPrice*(UnitsInStock+COALESCE(UnitsOnOrder,0))AS Price
FROM Products

94. SQL Datatypes

95. SQL Datatype Access Data type Description Storage Text
Use for text or combinations of text and numbers. 255 characters maximum
Memo
Memo is used for larger amounts of text. Stores up to 65,536 characters. Note: You cannot sort a memo field. However, they are searchable
Byte
Allows whole numbers from 0 to 255
1 byte
Integer
Allows whole numbers between -32,768 and 32,767
2 bytes
Long
Allows whole numbers between -2,147,483,648 and 2,147,483,647
4 bytes
Single
Single precision floating-point. Will handle most decimals
Double
Double precision floating-point. Will handle most decimals
8 bytes
Currency
Use for currency. Holds up to 15 digits of whole dollars, plus 4 decimal places. Tip: You can choose which country's currency to use
AutoNumber
AutoNumber fields automatically give each record its own number, usually starting at 1
Date/Time
Use for dates and times
Yes/No
A logical field can be displayed as Yes/No, True/False, or On/Off. In code, use the constants True and False (equivalent to -1 and 0). Note: Null values are not allowed in Yes/No fields
1 bit
OLE Object
Can store pictures, audio, video, or other BLOBs (Binary Large OBjects)
up to 1GB
Hyperlink
Contain links to other files, including web pages
Lookup Wizard
Let you type a list of options, which can then be chosen from a drop-down list

96. SQL Datatype MySQL: Text Data type Description CHAR(size)
Holds a fixed length string (can contain letters, numbers, and special characters). The fixed size is specified in parenthesis. Can store up to 255 characters
VARCHAR(size)
Holds a variable length string (can contain letters, numbers, and special characters). The maximum size is specified in parenthesis. Can store up to 255 characters. Note: If you put a greater value than 255 it will be converted to a TEXT type
TINYTEXT
Holds a string with a maximum length of 255 characters
TEXT
Holds a string with a maximum length of 65,535 characters
BLOB
For BLOBs (Binary Large OBjects). Holds up to 65,535 bytes of data
MEDIUMTEXT
Holds a string with a maximum length of 16,777,215 characters
MEDIUMBLOB
For BLOBs (Binary Large OBjects). Holds up to 16,777,215 bytes of data
LONGTEXT
Holds a string with a maximum length of 4,294,967,295 characters
LONGBLOB
For BLOBs (Binary Large OBjects). Holds up to 4,294,967,295 bytes of data
ENUM(x,y,z,etc.)
Let you enter a list of possible values. You can list up to values in an ENUM list. If a value is inserted that is not in the list, a blank value will be inserted.Note: The values are sorted in the order you enter them.
You enter the possible values in this format: ENUM('X','Y','Z')
SET
Similar to ENUM except that SET may contain up to 64 list items and can store more than one choice

97. SQL Datatype MySQL: Number Unsigned: integer cannot be negative
Description
TINYINT(size)
-128 to 127 normal. 0 to 255 UNSIGNED*. The maximum number of digits may be specified in parenthesis
SMALLINT(size)
to normal. 0 to UNSIGNED*. The maximum number of digits may be specified in parenthesis
MEDIUMINT(size)
to normal. 0 to UNSIGNED*. The maximum number of digits may be specified in parenthesis
INT(size)
to normal. 0 to UNSIGNED*. The maximum number of digits may be specified in parenthesis
BIGINT(size)
to normal. 0 to UNSIGNED*. The maximum number of digits may be specified in parenthesis
FLOAT(size,d)
A small number with a floating decimal point. The maximum number of digits may be specified in the size parameter. The maximum number of digits to the right of the decimal point is specified in the d parameter
DOUBLE(size,d)
A large number with a floating decimal point. The maximum number of digits may be specified in the size parameter. The maximum number of digits to the right of the decimal point is specified in the d parameter
DECIMAL(size,d)
A DOUBLE stored as a string , allowing for a fixed decimal point. The maximum number of digits may be specified in the size parameter. The maximum number of digits to the right of the decimal point is specified in the d parameter
Unsigned: integer cannot be negative

98. SQL Datatype MySQL: Date Data type Description DATE()
A date. Format: YYYY-MM-DDNote: The supported range is from ' ' to ' '
DATETIME()
*A date and time combination. Format: YYYY-MM-DD HH:MM:SSNote: The supported range is from ' :00:00' to ' :59:59'
TIMESTAMP()
*A timestamp. TIMESTAMP values are stored as the number of seconds since the Unix epoch (' :00:00' UTC). Format: YYYY-MM-DD HH:MM:SSNote: The supported range is from ' :00:01' UTC to ' :14:07' UTC
TIME()
A time. Format: HH:MM:SSNote: The supported range is from '-838:59:59' to '838:59:59'
YEAR()
A year in two-digit or four-digit format.Note: Values allowed in four-digit format: 1901 to Values allowed in two-digit format: 70 to 69, representing years from 1970 to 2069

99. Homework 5
Create one database containing several tables using PostgreSQL
10 SQL queries
Embedded queries
GroupBy queries
Join queries
SELECT * FROM Persons
WHERE lastname IN (SELECT lastname from Persons
where city=‘Sandnes’)
SELECT Customer, SUM(OrderPrice)
FROM CumOrders
GROUP BY Customer
HAVING SUM(OrderPrice)<2000
SELECT persons.lastname, persons.firstname, orders.orderNo
From Persons INNER JOIN Orders
ON persons.P_Id=orders.P_Id
ORDER BY persons.Lastname;

100. SQL Quiz