1. MIS2502: Data Analytics SQL 4– Putting Information Into a Database
Zhe (Joe) Deng

2. Database Management System
What do we want to do?
Database Management System
Get information out of the database (retrieve)
Put information into the database (modify/change)

3. Our relational database
A series of tables
Linked together through primary/foreign key relationships

4. To create a database We need to define
The tables
The fields (columns) within those tables
The data types of those fields
The primary/foreign key relationships
There are SQL commands that do each of those things
So let’s assume that we have a blank database and we needed to create the tables

5. CREATE statement (create a table)
CREATE TABLE schema_name.table_name ( columnName1 datatype [NULL][NOT NULL], columnName2 datatype [NULL][NOT NULL], … PRIMARY KEY (KeyName) );
Item
Description
schema_name
The schema that will contain the table
table_name
The name of the table
columnName
The name of the field
datatype
The datatype of the field
[NULL][NOT NULL]
Whether the field can be empty (i.e., null). The [] means the parameter is optional.
A primary key column cannot contain NULL values.
KeyName
The name of the field that will serve as the primary key.

6. Data types Each field can contain different types of data
That must be specified when the table is created
There are many data types; we’re only going to cover the most important ones
Data type
Description
Examples
INT
Integer
3, -10
DECIMAL(p,s)
Decimal. Example: decimal(5,2) is a number that has 3 digits before decimal and 2 digits after decimal (like ).
5 digits in total.
3.23,
VARCHAR(n)
String (numbers and letters) with maximum length n
'Hello', 'I like pizza', 'MySQL!'
DATETIME, DATE
Date/Time, or just Date
' :35:00', ' '
BOOLEAN
Boolean value
0 or 1

7. Looking at the “new” Customer table
The database management system stores this information about the table
It’s separate from the data in the table (i.e., Customer information)
This is called metadata – “data about data”
Column name
Data type
CustomerID
INT
FirstName
VARCHAR(45)
LastName
City
State ??
Zip
Customer

8. Example: Creating the Customer Table
CustomerID
FirstName
LastName
City
State
Zip
CREATE TABLE schema_name.table_name ( columnName1 datatype [NULL][NOT NULL], columnName2 datatype [NULL][NOT NULL], … PRIMARY KEY (KeyName) );
Based on this SQL statement:
The only required field is CustomerID – the rest can be left blank.
CustomerID is defined as the primary key.

9. Example: Creating the Customer Table
CREATE TABLE orderdb.Customer (
CustomerID INT NOT NULL ,
FirstName VARCHAR(45) NULL ,
LastName VARCHAR(45) NULL ,
City VARCHAR(45) NULL ,
State VARCHAR(2) NULL ,
Zip VARCHAR(10) NULL ,
PRIMARY KEY (CustomerID) );
Customer
CustomerID
FirstName
LastName
City
State
Zip
Based on this SQL statement:
The only required field is CustomerID – the rest can be left blank.
CustomerID is defined as the primary key.

10. So back to our CREATE statement
CREATE TABLE orderdb.Customer (
CustomerID INT NOT NULL , FirstName VARCHAR(45) NULL ,
LastName VARCHAR(45) NULL ,
City VARCHAR(45) NULL ,
State VARCHAR(2) NULL ,
Zip VARCHAR(10) NULL ,
PRIMARY KEY (CustomerID) );
FirstName can be a string of up to 45 letters and numbers.
Why 45? It’s the MySQL default.
State can be a string of up to 2 letters and numbers

11. NULL vs. NOT NULL
NULL values represent missing/empty data.
The NOT NULL constraint enforces a field to always contain a value.
This means that you cannot insert a new record, or update a record without adding a value to this field.
CREATE TABLE orderdb.Customer ( CustomerID INT NOT NULL , FirstName VARCHAR(45) NULL , LastName VARCHAR(45) NULL , City VARCHAR(45) NULL , State VARCHAR(2) NULL , Zip VARCHAR(10) NULL , PRIMARY KEY (CustomerID) );
Rule of Thumb
A primary key (e.g., CustomerID) column should be NOT NULL.
The rest can be left NULL.

12. Foreign Key
A foreign key in one table points to a primary key in another table.
CustomerID is a foreign key in the Order table, and a primary key in the Customer table
CREATE TABLE orderdb.`Order` (
OrderNumber INT NOT NULL , OrderDate DATETIME NULL ,
CustomerID INT NULL ,
PRIMARY KEY (OrderNumber) ,
FOREIGN KEY (CustomerID) REFERENCES orderdb.Customer(CustomerID) );
This ensures that every order is placed by a valid customer that already exists.

13. Some more CREATE statements
CREATE TABLE orderdb.Product ( ProductID INT NOT NULL , ProductName VARCHAR(45) NULL , Price DECIMAL(5,2) NULL , PRIMARY KEY (ProductID) ); CREATE TABLE orderdb.OrderProduct( OrderProductID INT NOT NULL , OrderNumber INT NULL , ProductID INT NULL , PRIMARY KEY (OrderProductID) , FOREIGN KEY (OrderNumber) REFERENCES orderdb.`Order`(OrderNumber), FOREIGN KEY (ProductID) REFERENCES orderdb.Product(ProductID)
DECIMAL(5, 2) indicates price can no larger than

14. Be careful! Removing tables
DROP TABLE schema_name.table_name; Example: DROP TABLE orderdb.Customer;
This deletes the entire table and all data!
It’s a pain to get it back (if you can at all)!
Be careful!

15. Changing a table’s metadata
Adds a column to the table
ALTER TABLE schema_name.table_name ADD COLUMN column_name datatype
[NULL][NOT NULL]; or
ALTER TABLE schema_name.table_name
DROP COLUMN column_name;
CHANGE COLUMN old_column_name new_column_name datatype [NULL][NOT NULL];
Removes a column from the table
Changes a column in the table

16. An example of each
ALTER TABLE orderdb.Product ADD COLUMN Manufacturer VARCHAR(45) NULL; ALTER TABLE orderdb.Product DROP COLUMN Manufacturer;
Adds ‘Manufacturer’ column to Product table
Removes ‘Manufacturer’ column from Product table

17. An example of each
ALTER TABLE orderdb.Product CHANGE COLUMN Price SalesPrice DECIMAL(6,2) NULL; ?????
Changes name of Price column in Product table to SalesPrice and its data type to DECIMAL(6,2)
Changes data type of Price column in Product table to DECIMAL(6,2) but leaves the name unchanged.

18. Adding a row to a table (versus columns)
A change in the table structure
Done using ALTER TABLE
Adding a column
A change in the table data
Done using INSERT INTO
Adding a row

19. Adding a row
INSERT INTO schema_name.table_name (columnName1, columnName2, columnName3) VALUES (value1, value2, value3);
Item
Description
schema_name
The schema that contains the table
table_name
The name of the table
columnName
The name of the field
value
The data value for the field
datatype
The datatype of the field
BIG TIP: The order of the values MUST match the order of the field names!

20. INSERT example
INSERT INTO schema_name.table_name (columnName1, columnName2, columnName3) VALUES (value1, value2, value3);
CustomerID
FirstName
LastName
City
State
Zip
1001
Greg
House
Princeton NJ
09120
1002
Lisa
Cuddy
Plainsboro
09123
1003
James
Wilson
Pittsgrove
09121
1004
Eric
Foreman
Warminster PA
19111
1005
Chris
Taub
BIG TIP: Note that field names are surrounded by back quotes (`) and string field values are surrounded by regular single quotes (')

21. INSERT example
INSERT INTO orderdb.Customer (CustomerID, FirstName, LastName, City, State, Zip)
VALUES (1005, 'Chris', 'Taub', 'Princeton', 'NJ', '09120');
CustomerID
FirstName
LastName
City
State
Zip
1001
Greg
House
Princeton NJ
09120
1002
Lisa
Cuddy
Plainsboro
09123
1003
James
Wilson
Pittsgrove
09121
1004
Eric
Foreman
Warminster PA
19111
1005
Chris
Taub
BIG TIP: Note that field names are surrounded by back quotes (`) and string field values are surrounded by regular single quotes (')

22. Changing a row UPDATE schema_name.table_name
SET columnName1=value1, columnName2=value2
WHERE condition;
Item
Description
schema_name
The schema that contains the table
table_name
The name of the table
columnName
The name of the field
value
The data value for the field
condition
A conditional statement to specify the records which should be changed

23. UDPATE example
UPDATE schema_name.table_name SET columnName1=value1, columnName2=value2 WHERE condition;
ProductID
ProductName
Price
2251
Honey Nut Cheerios
4.50
2282
Bananas
1.29
2505
Eggo Waffles
2.99
ProductID
ProductName
Price
2251
Cheerios
3.99
2282
Bananas
1.29
2505
Eggo Waffles
2.99
Product

24. UDPATE example UPDATE orderdb.Product
SET ProductName='Honey Nut Cheerios', Price=4.50
WHERE ProductID=2251;
The “safest” way to UPDATE is one record at a time, based on the primary key field.
ProductID
ProductName
Price
2251
Honey Nut Cheerios
4.50
2282
Bananas
1.29
2505
Eggo Waffles
2.99
ProductID
ProductName
Price
2251
Cheerios
3.99
2282
Bananas
1.29
2505
Eggo Waffles
2.99
Product

25. Changing multiple rows
UPDATE orderdb.Customer
SET City='Cherry Hill'
WHERE State='NJ';
CustomerID
FirstName
LastName
City
State
Zip
1001
Greg
House
Princeton NJ
09120
1002
Lisa
Cuddy
Plainsboro
09123
1003
James
Wilson
Pittsgrove
09121
1004
Eric
Foreman
Warminster PA
19111
Be careful!
You can do a lot of damage with a query like this!
CustomerID
FirstName
LastName
City
State
Zip
1001
Greg
House
Cherry Hill NJ
09120
1002
Lisa
Cuddy
09123
1003
James
Wilson
09121
1004
Eric
Foreman
Warminster PA
19111

26. Deleting a row DELETE FROM schema_name.table_name WHERE condition;
Item
Description
schema_name
The schema that contains the table
table_name
The name of the table
condition
A conditional statement to specify the records which should be changed

27. Again, the “safest” way to DELETE is based on the primary key field.
DELETE example
CustomerID
FirstName
LastName
City
State
Zip
1001
Greg
House
Princeton NJ
09120
1002
Lisa
Cuddy
Plainsboro
09123
1003
James
Wilson
Pittsgrove
09121
1004
Eric
Foreman
Warminster PA
19111
CustomerID
FirstName
LastName
City
State
Zip
1001
Greg
House
Princeton NJ
09120
1002
Lisa
Cuddy
Plainsboro
09123
1003
James
Wilson
Pittsgrove
09121
DELETE FROM orderdb.Customer WHERE CustomerID=1004;
Again, the “safest” way to DELETE is based on the primary key field.

28. Deleting multiple rows
Avoid doing this!
Deleting multiple rows
DELETE FROM orderdb.Customer
WHERE CustomerID>1002;
CustomerID
FirstName
LastName
City
State
Zip
1001
Greg
House
Princeton NJ
09120
1002
Lisa
Cuddy
Plainsboro
09123
1003
James
Wilson
Pittsgrove
09121
1004
Eric
Foreman
Warminster PA
19111
CustomerID
FirstName
LastName
City
State
Zip
1001
Greg
House
Princeton NJ
09120
1002
Lisa
Cuddy
Plainsboro
09123

29. One more DELETE example
DELETE FROM orderdb.Customer
WHERE State='NJ' AND Zip='09121‘;
CustomerID
FirstName
LastName
City
State
Zip
1001
Greg
House
Princeton NJ
09120
1002
Lisa
Cuddy
Plainsboro
09123
1003
James
Wilson
Pittsgrove
09121
1004
Eric
Foreman
Warminster PA
19111
CustomerID
FirstName
LastName
City
State
Zip
1001
Greg
House
Princeton NJ
09120
1002
Lisa
Cuddy
Plainsboro
09123
1004
Eric
Foreman
Warminster PA
19111

30. Summary Given the schema of a database, be able to
Create a table using CREATE TABLE
Change the structure of a table using ALTER TABLE
Add a record to a table using INSERT
Update an existing record in a table using UPDATE
Delete a record from a table using DELETE
Be familiar with using conditional statements in the UPDATE and DELETE statements using WHERE
Be familiar with MySQL data types (INT, DECIMAL, BOOLEAN, DATETIME/DATE, VARCHAR, etc.)

31. Summary: DDL and DML Commands
DDL(Data Definition Language) : DDL or Data Definition Language actually consists of the SQL commands that can be used to define the database schema. It simply deals with descriptions of the database schema and is used to create and modify the structure of database objects in database.
CREATE – is used to create the database or its objects (like table, index, function, views, store procedure and triggers).
DROP – is used to delete objects from the database.
ALTER-is used to alter the structure of the database.
DML(Data Manipulation Language) : The SQL commands that deals with the manipulation of data present in database belong to DML or Data Manipulation Language and this includes most of the SQL statements.
SELECT – is used to retrieve data from the a database.
INSERT – is used to insert data into a table.
UPDATE – is used to update existing data within a table.
DELETE – is used to delete records from a database table.
More on DDL, DML, DCL and TCL Commands can be found here (

32. Time for our 6th ICA!