Hi all...



Can we discuss briefly about the Union and Union All in sql.



Thanks in advance...

Hi all...


Union :
The UNION command is used to select related information from two tables, much like the JOIN command. However, when using the UNION command all selected columns need to be of the same data type.

Syntax:
select * from table1_name
union
select * from table2_name


Union All:
The UNION ALL command is equal to the UNION command, except that UNION ALL selects all values.

Syntax:
select * from table1_name
union all
select * from table2_name

Thanks...

Hi vinoth,

Could you please suggest me which one is good method in the following condition.

Assume that this table contains more than 1 lakh records.

1. Using UNION (same table)
select * from employee where age=25
union
select * from employee where age=26

2. Using OR (same table)
select * from employee where age=25 or age=26

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