SQL UNION Operators - Steem Alliance Community.

Hello Everyone,

Good evening everyone, how are you, i hope you all guys will happy and good. By the grace of God, i am also good. Today i am here with new post in which we discuss the SQL Union operators. There are two types of operator. One is simple UNION and second is UNION ALL. we will also explore its syntax by using simple example.

In the field of database, SQL play an crucial role in manipulating data. The UNION operator is used for combining the results of multiple SELECT statements into a single result. by using UNION operators, data will increased by rows wise.

It removes duplicate rows automatically and provide the data set ideal. Some important rules are needed to follow for joins. The columns in each SELECT statement must have the same data types and same numbers of columns in corresponding positions.

UNION Syntax

SELECT column1, column2
FROM table1
UNION
SELECT column1, column2
FROM table2

The SQL UNION operator is vital for combining and aggregating data from various sources in a database. Knowing its syntax, features, and best practices empowers professionals to streamline data tasks, improving database efficiency.

User1

NO	sector	name_1
1	1000	ALI HAMZA
2	1000	IMRAN
3	1000	SIKANDAR

User2

NO	sector	name_1
4	15	Mustafa
5	106	Farhan
6	90	abdullah

The above are two table on which we will apply the SQL UNION then see the result.

Select * from User1
Union
Select * from User2

See the below Result

NO	sector	name_1
1	1000	ALI HAMZA
2	1000	IMRAN
3	1000	SIKANDAR
4	15	Mustafa
5	106	Farhan
6	90	abdullah

Img Src

If we face the data requirement in which we need to make data set will allowing the duplication in data then we will use the UNION ALL operator.

We can also use the union and union all operators by using with clause. We can apply the filter on each select queries to get the data according to requirement.

For example i want to get those data that just have sector 1000 and sector 15 then we will apply the where clause on both tables then use the union operator to show and get the combine results. Below is the query that will meet our requirements.

Select * from User1 
where sector in (1000 , 15)
Union
Select * from User2 
where sector in (1000 , 15)

Now see the result.

NO	sector	name_1
1	1000	ALI HAMZA
2	1000	IMRAN
3	1000	SIKANDAR
4	15	Mustafa

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