Structured Query Language

Structured Query Language

SQL stands for “Structured Query Language”. Used for accessing and modifying information in the database. Some of the SQL commands used in SQL programming are SELECT Statement, UPDATE Statement, INSERT INTO Statement, DELETE Statement, WHERE Clause, ORDER BY Clause, GROUP BY Clause, etc.

SQL commands are instructions used to communicate with the database to perform specific task that work with data. SQL commands are grouped into four major categories Data Definition Language (DDL) - Data Manipulation Language (DML) - Transaction Control Language (TCL) - Data Control Language (DCL) -

Data Definition Language (DDL) – These SQL commands are used for creating, modifying, and dropping the structure of database objects. The commands are CREATE, ALTER, DROP, RENAME, and TRUNCATE.

Data Manipulation Language (DML) – These SQL commands are used for storing, retrieving, modifying, and deleting data. These commands are SELECT, INSERT, UPDATE, and DELETE.

Transaction Control Language (TCL) – These SQL commands are used for managing changes affecting the data. These commands are COMMIT, ROLLBACK, and SAVEPOINT. Data Control Language (DCL) - These SQL commands are used for providing security to database objects. These commands are GRANT and REVOKE.

Some basic Data Types NUMBER used to store integer numbers, floating point numbers. DECIMAL used to store numbers CHAR(n)used to store characters of fixed length, n is the no. of characters. VARCHAR(n) used to store characters of varying length. DATE used for date values TIME used for time values and has at least 8 positions with components hh:mm:ss.

DDL Command The CREATE TABLE Statement CREATE TABLE statement is used to create a table in a database. Syntax Eg) CREATE TABLE customer(First_Name char(50),Last_Name char(50),Address char(50),City char(50),Country char(25),Birth_Date date); DESC customer; :- will display the structure of the table CREATE TABLE table_name ( column_name1 data_type, column_name2 data_type, column_name3 data_type, .... );

Question: Create a Table ‘student’ with following fields CREATE TABLE STUDENT (SID CHAR(20), FIRST_NAME CHAR(20), LAST_NAME CHAR(20), ADDRESS CHAR(20), PHONE CHAR(10), LOGIN CHAR(20), PASSWORD CHAR(20)); DESCRIBE STUDENT;

DDL Command The CREATE TABLE AS Statement create a table from an existing table by copying the existing table's columns. SYNTAX - COPYING ALL COLUMNS FROM ANOTHER TABLE CREATE TABLE new_table AS (SELECT * FROM old_table); If there were records in the OLD table, then the NEW table would also contain the records selected by the SELECT statement.

The CREATE TABLE AS Statement Question: Create a new table TEMP from TEST1, with all date and colums Table test1 CREATE TABLE TEMP AS (SELECT * FROM TEST1); SELECT * FROM TEMP;

DDL Command The CREATE TABLE AS Statement SYNTAX - COPYING SELECTED COLUMNS FROM ANOTHER TABLE CREATE TABLE new_table AS (SELECT column_1, column2, ... column_n FROM old_table);

The CREATE TABLE AS Statement Question: Create a new table TEMP1 from TEST1, with 1 colums NAME Table test1 CREATE TABLE TEMP1 AS (SELECT NAME FROM TEST1); SELECT * FROM TEMP;

The CREATE TABLE AS Statement Question: Create a new table TEMP2 from TEST1, with all column and condition age >= 33 Table test1 CREATE TABLE TEMP2 AS (SELECT * FROM TEST1 WHERE AGE >=33); SELECT * FROM TEMP2;

DDL Command The CREATE TABLE AS Statement SYNTAX - COPYING SELECTED COLUMNS FROM MULTIPLE TABLES CREATE TABLE new_table AS (SELECT TABLE1.column_1, .. TABLE2.colum1,.. FROM old_table_1, old_table_2, ... old_table_n);

The CREATE TABLE AS Statement Question: Create a new table TEMP3 from TEST1 and TEST2 , with columns NAME from TEST1 & SALARY from TEST2 With condition NAME in TEST1= NAME_S in TEST2 Table test Table test2 CREATE TABLE TEMP3 AS (SELECT TEST1.NAME, TEST2.SALARY FROM TEST1, TEST2 WHERE TEST1.NAME=TEST2.NAME_S); SELECT * FROM TEMP3;

DDL Command The CREATE TABLE AS Statement SYNTAX -create a table from another table without copying any values from the old table CREATE TABLE new_table AS (SELECT * FROM old_table WHERE 1=2);

DDL Command - ALTER The ALTER TABLE Statement ALTER TABLE statement is used to add, delete, or modify columns in an existing table. To add a column in a table syntax: ALTER TABLE table_name ADD column_name datatype; Eg) ALTER TABLE customer ADD Gender char(1);

Question: Add a new column in the ‘student’ table as ‘GENDER’ CHAR(1) ALTER TABLE STUDENT ADD GENDER CHAR (1); DESC STUDENT;

DDL Command - ALTER To delete a column in a table, syntax: ALTER TABLE table_name DROP COLUMN column_name; Eg)ALTER table customer drop column Birth_Date; To change the data type of a column in a table, ALTER TABLE table_name MODIFY column_name datatype Eg) ALTER TABLE customer MODIFY Address char(100);

Question: Delete the colunm ‘PHONE’ from ‘student’ table ALTER TABLE STUDENT DROP COLUMN PHONE; DESC STUDENT;

Question: Modify the length of ‘ADDRESS’ to 50 in the ‘student’ table ALTER TABLE STUDENT MODIFY ADDRESS CHAR(50); DESC STUDENT;

DDL Command - ALTER To rename a column in a table, syntax: ALTER TABLE table_name RENAME COLUMN column 1 TO column 2; Eg) ALTER table customer RENAME COLUMN Address TO Addr;

Question: Rename the column ‘FIRST_NAME’ to ‘S_NAME’ in the ‘student’ table ALTER TABLE STUDENT RENAME COLUMN FIRST_NAME TO S_NAME; DESC STUDENT;

DDL Command - Drop The DROP TABLE Statement The DROP TABLE statement is used to delete a table. DROP TABLE table_name; DROP TABLE STUDENT;

DDL Command The TRUNCATE TABLE Statement If we only want to delete the data inside the table, and not the table itself then, use the TRUNCATE TABLE statement: TRUNCATE TABLE table_name TRUNCATE TABLE STUDEN T;

DDL Command The RENAME Statement The SQL RENAME command is used to change the name of the table. Syntax to rename a table RENAME old_table_name To new_table_name; Rename the ‘student ‘ table to ‘MCASTUDENTs’ RENAME STUDENT TO MACSTUDENTS;

DML Command The INSERT INTO Statement INSERT INTO statement is used to insert a new row in a table. It is possible to write the INSERT INTO statement in two forms. The first form doesn't specify the column names where the data will be inserted, only their values: INSERT INTO table_name VALUES (value1, value2, value3,...) The second form specifies both the column names and the values to be inserted: INSERT INTO table_name (column1, column2, column3,...) VALUES (value1, value2, value3,...)

Question: Insert sid, first_name, last_name, address, phone, login and password in the student table Does not specify the column name INSERT INTO STUDENT VALUES('S100', 'APPU', 'KUTTAN','ADDRESS', ' ','APPUS','SUTTAN'); SELECT * FROM STUDENT;

Question: Insert sid, first_name, last_name, and phone in the student table INSERT INTO STUDENT (SID,FIRST_NAME,LAST_NAME,PHONE) VALUES('S102','KUKKU','KOO',' '); SELECT * FROM STUDENT;

DML Command The UPDATE statement Used to update existing records in a table. UPDATE table_name SET column1=value, column2=value2,... WHERE some_column=some_value Eg)UPDATE Store_Information SET Sales = 500 WHERE store_name = "Los Angeles" AND Date = "Jan "

Question: Change the SID of KUKKU to ‘S101’ in the student table UPDATE STUDENT SET SID='S101' WHERE FIRST_NAME='KUKKU'; SELECT * FROM STUDENT;

DML Command The SELECT Statement The SELECT statement is used to select data from a database. SELECT column_name(s) FROM table_name & SELECT * FROM table_name The WHERE clause is used to extract only those records that fulfill a specified criterion. SELECT column_name(s) FROM table_name WHERE column_name operator value

Question: Display all Sid, First_name and Phone from the student table SELECT SID,FIRST_NAME,PHONE FROM STUDENT;

DML Command The DELETE Statement The DELETE statement is used to delete rows in a table. DELETE FROM table_name WHERE some_column=some_value Eg)DELETE FROM Store_Information WHERE store_name = "Los Angeles" It is possible to delete all rows in a table without deleting the table. DELETE FROM table_name or DELETE * FROM table_name

Question: Delete the record where SID =‘S102’ from the student table DELETE from student where SID='S102'; SELECT * FROM STUDENT;

Where clause Used to specify a condition while fetching the data from single table or joining with multiple tables. Used to filter the records and fetching only necessary records. It can used in SELECT, UPDATE, DELETE statement, etc., Syntax: SELECT column1, column2, columnN FROM table_name WHERE [condition] Eg SELECT ID, NAME, SALARY FROM CUSTOMERS WHERE SALARY > 2000;

AND Operator: The AND operator allows the existence of multiple conditions in an SQL statement's WHERE clause. Syntax: SELECT column1, column2, columnN FROM table_name WHERE [condition1] AND [condition2]...AND [conditionN]; SELECT ID, NAME, SALARY FROM CUSTOMERS WHERE SALARY > 2000 AND age < 25;

Question: List all details from the TAB1 table where S_Name=“saji” & weight>10 TAB1 SELECT * FROM TAB1 WHERE S_NAME='SAJI' AND WEIGHT>10;

OR Operator: The OR operator is used to combine multiple conditions in an SQL statement's WHERE clause. SELECT column1, column2, columnN FROM table_name WHERE [condition1] OR [condition2]. SELECT ID, NAME, SALARY FROM CUSTOMERS WHERE SALARY > 2000 OR age < 25;

Question: List all details from the TAB1 table where S_NAME=“saji” OR weight>50 TAB1 SELECT * FROM TAB1 WHERE S_NAME=‘SAJI’ OR WEIGHT>50;

"AND" & "OR Operator: SELECT * FROM suppliers WHERE (city = 'New York' AND name = 'IBM') OR (ranking >= 10);

Question: List all details from the TAB1 table where ROLL_NO>101 AND ROLL_NO<103 OR weight>50 TAB1 SELECT * FROM TAB1 WHERE (ROLL_NO>101 AND ROLL_NO<103) OR WEIGHT>50;

IN SELECT * FROM STUDENT WHERE FIRST_NAME IN ('APPU', 'RAJI', 'SAJAN'); This statement will select the all columns from the student table where the first_name is equal to either: APPU, RAJI or SAJAN. It will return the rows if it is ANY of these values.

IN The IN conditional operator can be rewritten by using compound conditions using the equals operator and combining it with OR SELECT * FROM STUDENT WHERE FIRST_NAME ='APPU' OR FIRST_NAME='RAJI' OR FIRST_NAME= 'SAJAN'; Same o/p

BETWEEN NUMERIC The BETWEEN conditional operator is used to test to see whether or not a value (stated before the keyword BETWEEN) is "between" the two values stated after the keyword BETWEEN. SELECT * FROM STUDENT WHERE AGE BETWEEN 20 AND 30;

BETWEEN NUMERIC QUESTION: Select all records from TEST2 table where age >=40 & <=50 Table test2 SELECT * FROM TEST2 WHERE SALARY BETWEEN 40 AND 50;

BETWEEN DATE QUESTION: Select all records from TEMP table where DOB >=‘02-JAN-14’ AND <=’12-MAR-14’ Table TEMP SELECT * FROM TEMP WHERE DOB BETWEEN '02-JAN-14' AND '12-MAR-14';

BETWEEN USING NOT OPERATOR QUESTION: Select all records from TEST2 table where age NOT >=40 & <=50 Table test2 SELECT * FROM TEST2 WHERE SALARY NOT BETWEEN 40 AND 50;

Constraints in SQL Constraints will be given to columns at the time of table creation Used to limit the type of data that can go into a table. This ensures the accuracy and reliability of the data in the database.

Constraints NOT NULL Constraint: Ensures that a column cannot have NULL value. Example: The following SQL creates a new table called TAB1 and adds 3 columns, 2 of which, ID and NAME, specify not to accept NULLs: CREATE TABLE TAB1( ID INT NOT NULL, NAME VARCHAR (20) NOT NULL, AGE INT); If the table has already been created, then to add a NOT NULL constraint to AGE column ALTER TABLE TAB1 MODIFY AGE INT NOT NULL;

Constraints DEFAULT Constraint: Provides a default value for a column when none is specified. Example: following SQL creates a new table called TAB1 and adds 3 columns. SALARY column is set to by default, so in case INSERT INTO statement does not provide a value for this column, then by default this column would be set to CREATE TABLE TAB1( ID INT NOT NULL, NAME VARCHAR (20) NOT NULL, SALARY DECIMAL(10,2) DEFAULT );

Constraints UNIQUE Constraint: Ensures that all values in a column are different. Example: following SQL creates a new table called TAB1 and adds 3 columns. AGE column is set to UNIQUE, so that can not have two records with same age: CREATE TABLE TAB1( ID INT NOT NULL, NAME VARCHAR (20) NOT NULL, AGE INT NOT NULL UNIQUE);

Constraints PRIMARY Key: Uniquely identified each rows/records in a database table. Primary keys must contain unique values. A primary key column cannot have NULL values. A table can have only one primary key, which may consist of single or multiple fields. When multiple fields are used as a primary key, they are called a composite key.

Create Primary Key: Here is the syntax to define ID attribute as a primary key in a TAB1 table. CREATE TABLE TAB1( ID INT NOT NULL, NAME VARCHAR(20)NOT NULL, AGE INT NOT NULL,PRIMARY KEY (ID));

Constraints FOREIGN Key: Uniquely identified a rows/records in any another table. A foreign key is a key used to link two tables together. This is sometimes called a referencing key. The relationship between 2 tables matches the Primary Key in one of the tables with a Foreign Key in the second table.

Example: Consider the structure of the two tables as follows: TAB1 table: CREATE TABLE TAB1( ID INT NOT NULL, NAME VARCHAR(20)NOT NULL, AGE INT NOT NULL,PRIMARY KEY (ID)); TAB2 table: CREATE TABLE TAB2( ID INT NOT NULL, SID INT REFERENCES TAB1(ID), SALARY DECIMAL(10,2)NOT NULL,PRIMARY KEY (ID));

Constraints CHECK Constraint: The CHECK constraint ensures that all values in a column satisfy certain conditions. Example: following SQL creates a new table called TAB1 and adds 3 columns. CHECK with AGE column, so that you can not have any VALUE below 10 years: CREATE TABLE TAB1( ID INT NOT NULL, NAME CHAR(20) NOT NULL, AGE INT NOT NULL CHECK(AGE>10),PRIMARY KEY (ID));

Constraints INDEX: Use to create and retrieve data from the database very quickly. Index can be created by using single or group of columns in a table. Example: Following SQL creates a new table called TAB1 and adds 3 columns: CREATE TABLE TAB1( ID INT NOT NULL, NAME CHAR(20) NOT NULL, AGE INT NOT NULL CHECK(AGE>10),PRIMARY KEY (ID));

To create index on single or multiple columns using the following syntax: CREATE INDEX index_name ON table_name ( column1, column2.....); To create an INDEX on AGE column SQL syntax: CREATE INDEX TAB1_age ON TAB1 ( AGE );

ORDER BY clause is used to sort the data in ascending or descending order, based on one or more columns. Syntax: SELECT column-list FROM table_name [WHERE condition] [ORDER BY column1, column2, .. columnN] [ASC | DESC]; Following is an example, which would sort the result in ascending order by NAME SQL> SELECT * FROM TAB1 ORDER BY NAME; Following is an example, which would sort the result in descending order by NAME: SQL> SELECT * FROM TAB1 ORDER BY NAME DESC;

DISTINCT keyword is used with SELECT statement to eliminate all the duplicate records and fetching only unique records. Syntax: SELECT DISTINCT column1, column2,.....columnN FROM table_name WHERE [condition] Example SELECT DISTINCT SALARY FROM TAB1 ORDER BY SALARY;

LIKE clause is used to compare a value to similar values using wildcard operators. There are two wildcards used in conjunction with the LIKE operator: The percent sign (%) The underscore (_) The percent sign represents zero, one, or multiple characters. The underscore represents a single number or character.

Example: WHERE SALARY LIKE '200%‘ Finds any values that start with 200 WHERE SALARY LIKE '%200%‘ Finds any values that have 200 in any position WHERE SALARY LIKE '_00%‘ Finds any values that have 00 in the second and third positions WHERE SALARY LIKE '%2'Finds any values that end with 2

GROUP BY clause Used to arrange identical data into groups. Syntax: SELECT column1, column2 FROM table_name GROUP BY column1, column2;

GROUP BY clause Consider the CUSTOMERS table is having the following records: to know the total amount of salary on each customer, then GROUP BY query would be as follows: SELECT NAME, SUM(SALARY) FROM CUSTOMER GROUP BY NAME;

Aggregate functions Provide mathematical operations. count() - counts a number of rows sum() - compute sum avg() - compute average min() - compute minimum max() - compute maximum

Aggregate functions SQL COUNT Function - Used to count the number of rows in a database table. To count total number of rows in this table, then SELECT COUNT(*) FROM TAB1 ; want to count the number of records for AJI, then SELECT COUNT(*) FROM TAB1 WHERE name=“AJI";

Aggregate functions SQL MAX Function To select the highest (maximum) value for a certain column. to fetch maximum value of AGE, SELECT MAX(AGE) FROM TAB1; SQL MIN Function - to select the lowest (minimum) value for a certain column. to fetch minimum value of AGE SELECT MIN(AGE) FROM TAB1;

Aggregate functions SQL AVG Function - selects the average value for certain table column. SELECT AVG(AGE) FROM TAB1; SQL SUM Function - selecting the total for a numeric column. SELECT SUM(AGE) FROM TAB1; To take sum of various records set using GROUP BY clause. Following example will sum up all the records related to a single person and you will have total DEPOSIT by every person. SELECT NAME,SUM(DEPOSIT) FROM BANK GROUP BY NAME;

Aggregate functions SQL SQRT Functions - This is used to generate a square root of a given number. SELECT name, SQRT(AGE) FROM TAB1; SQL UPPER Functions - converts the value of a field to uppercase SELECT UPPER(FIRST_NAME) FROM STUDENT;

Aggregate functions SQL LOWER Functions - converts the value of a field to LOWERCASE SELECT LOWER(FIRST_NAME) FROM STUDENT;

set operators SQL set operators allows combine results from two or more SELECT statements. They are UNION UNION ALL INTERSECT MINUS (EXCEPT)

set operators Union Clause UNION clause/operator is used to combine the result-set of two or more SELECT statements SELECT statement within the UNION must have the same number of columns. With same data type UNION operator selects only distinct values by default. syntax SELECT column_name(s) FROM table1 UNION SELECT column_name(s) FROM table2;

set operators Union Clause To allow duplicate values, use the ALL keyword with UNION. Syntax SELECT column_name(s) FROM table1 UNION ALL SELECT column_name(s) FROM table2;

set operators Union clause Table test1 Table test2 SELECT NAME FROM TEST1 UNION SELECT NAME FROM TEST2;

set operators UNION ALL clause Table test Table test2 SELECT NAME FROM TEST1 UNION ALL SELECT NAME FROM TEST2;

set operators INTERSECT Returns any distinct values that are returned by both the query on the left and right sides of the INTERSECT operand. Syntax SELECT column_name(s) FROM table1 INTERSECT SELECT column_name(s) FROM table2;

set operators INTERSECT Table test Table test2 SELECT NAME FROM TEST1 INTERSECT SELECT NAME_S FROM TEST2;

set operators MINUS returns any distinct values from the left query that are not also found on the right query. select * from test1 where name='AJI' select * from test2 where name_s='AJI'

set operators MINUS Table test Table test2 SELECT NAME FROM TEST1 MINUS SELECT NAME_S FROM TEST2;

JOIN Used to combine rows from two or more tables A JOIN is a means for combining fields from two tables by using values common to each.

JOIN Table test Table test2 SELECT NAME,SEX FROM TEST1,TEST2 WHERE TEST1.NAME=TEST2.NAME_S;

JOIN Need at least one common field and have a relationship between them The are two types of SQL JOINS - EQUI JOIN and NON EQUI JOIN 1) SQL EQUI JOIN : The SQL EQUI JOIN is a simple sql join uses the equal sign(=) as the comparison operator for the condition. It has two types - SQL Outer join and SQL Inner join. 2) SQL NON EQUI JOIN : The SQL NON EQUI JOIN is a join uses comparison operator other than the equal sign like >, <, >=, <= with the condition.

SQL EQUI JOIN can be classified into two types – INNER JOIN and OUTER JOIN 1. SQL INNER JOIN This type of EQUI JOIN returns all rows from tables where the key record of one table is equal to the key records of another table. 2. SQL OUTER JOIN This type of EQUI JOIN returns all rows from one table and only those rows from the secondary table where the joined condition is satisfying i.e. the columns are equal in both tables.

JOIN

INNER JOIN: Returns rows when there is a match in both tables. When the join-condition is satisfied, column values for each matched pair of rows of A and B are combined into a result row. Syntax: SELECT table1.column1, table2.column2... FROM table1 INNER JOIN table2 ON table1.common_field = table2.common_field;

TAB TAB2 SELECT ID FROM TAB1 INNER JOIN TAB2 ON TAB1.ID=TAB2.SID;

NATURAL JOIN Type of EQUI JOIN and is structured in such a way that, columns with same name of associate tables will appear once only The associated tables have one or more pairs of identically named columns. The columns must be the same data type. Don’t use ON clause in a natural join. Syntax Select * FROM table1 NATURAL JOIN table2;

NATURAL JOIN SELECT * FROM foods NATURAL JOIN company;

OUTER JOIN Returns all rows from both the tables which satisfy the join condition along with rows which do not satisfy the join condition. They are LEFT OUTER JOIN or LEFT JOIN RIGHT OUTER JOIN or RIGHT JOIN FULL OUTER JOIN

LEFT JOIN: Returns all rows from the left table, even if there are no matches in the right table. joins two tables and fetches rows based on a condition, which are matching in both the tables, and the unmatched rows will also be available from the table before the JOIN clause Syntax: Select * FROM table1 LEFT OUTER JOIN table2 ON table1.column_name=table2.column_name;

LEFT JOIN: SQL LEFT join fetches a complete set of records from table1, with the matching records (depending upon the availability) in table2. The result is NULL in the right side when no matching will take place.

LEFT JOIN TAB TAB2 SELECT * FROM TAB1 LEFT OUTER JOIN TAB2 ON TAB1.ID=TAB2.SID

RIGHT JOIN joins two tables and fetches rows based on a condition, which are matching in both the tables, and the unmatched rows will also be available from the table written after the JOIN clause Syntax Select * FROM table1 RIGHT OUTER JOIN table2 ON table1.column_name=table2.column_name ;

RIGHT join fetches a complete set of records from table2, i.e. the rightmost table after JOIN clause, with the matching records (depending upon the availability) in table1. The result is NULL in the left side when no matching will take place.

RIGHT JOIN TAB TAB2 SELECT * FROM TAB1 RIGHT OUTER JOIN TAB2 ON TAB1.ID=TAB2.SID

FULL OUTER JOIN combines the results of both left and right outer joins and returns all (matched or unmatched) rows from the tables on both sides of the join clause. Syntax SELECT * FROM table1 FULL OUTER JOIN table2 ON table1.column_name=table2.column_name ;

FULL OUTER JOIN TAB TAB2 SELECT * FROM TAB1 FULL OUTER JOIN TAB2 ON TAB1.ID=TAB2.SID

Alias Rename a table or a column temporarily by giving another name known as alias. The column aliases are used to rename a table's columns for the purpose of a particular SQL query. SELECT column_name AS alias_name FROM table_name WHERE [condition];

Alias Table test1 SELECT NAME AS PERSON, AGE AS OLD FROM TEST1;

A SELF JOIN which is used to join a table to itself In this join, the table appears twice after the FROM clause and is followed by aliases for the tables that qualify column names in the join condition In this join those rows are returned from the table which are satisfying the conditions.

SELF JOIN TAB TAB2 SELECT A.ID, B.ID FROM TAB1 A,TAB1 B WHERE A.ID=B.ID;

Joining table through referential-integrity Referential integrity is made up by the combination of a primary key and a foreign key.

Joining table through referential-integrity Display rollno, name and marks TAB TAB2 SELECT TAB1.ROLLNO, TAB1.NAME,TAB2.MARK FROM TAB1,TAB2 WHERE TAB1.ROLLNO=TAB2.ROLLNO;

Joining table through referential-integrity Display rollno, name and marks whose marks >40 TAB TAB2 SELECT TAB1.ROLLNO, TAB1.NAME,TAB2.MARK FROM TAB1,TAB2 WHERE TAB1.ROLLNO=TAB2.ROLLNO AND TAB2.MARK >40

Joining table with group by and order by Display rollno, name and total subject marks of each student TAB TAB2 SELECT TAB1.ROLLNO, TAB1.NAME, SUM(TAB2.MARK) FROM TAB1,TAB2 WHERE TAB1.ROLLNO=TAB2.ROLLNO GROUP BY TAB1.ROLLNO,TAB1.NAME ORDER BY TAB1.ROLLNO;

Structured Query Language

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