SQL UNION Operator

SQL UNION Operator.

The UNION operator is used to combine the result sets of two or more SELECT statements. For UNION, every SELECT statement must have same number of columns with same data type and must be in same order. It will return the distinct values by removing the duplicate rows.

Syntax:

SELECT columnList FROM table1 UNION SELECT columnList FROM table2;

Example:

SELECT EMP_NAME, SALARY FROM EMPLOYEE UNION SELECT EMP_NAME, AGE FROM EMPLOYEE1;

Output:

EMP_NAME SALARY Nidhi 28 Nidhi 48000 Parbhjot 28 Parbhjot 35000 Parbhjot 46000 Parmender 45000

SQL UNION ALL Operator.

It works same as UNION operator only difference is that it returns the duplicate rows.

Syntax:

SELECT columnList FROM table1 UNION ALL SELECT columnList FROM table2;

Example:

SELECT EMP_NAME, SALARY FROM EMPLOYEE UNION ALL SELECT EMP_NAME, AGE FROM EMPLOYEE1;

Output:

EMP_NAME SALARY Parbhjot 35000 Parmender 45000 Nidhi 48000 Parbhjot 46000 Parmender 45000 Parbhjot 28 Nidhi 28