How to using union in SQL?

Question

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SQL-Server-2005

hello,
I want to get two table with name's "Orders_T" and "Domain_T" data with a query in asp.net but my query dose not work:

SQL

SELECT * FROM dbo.Orders_T
UNION all
SELECT *
FROM   dbo.Domain_T

Please help me.
thank you for your help.

Posted 23-Jul-11 22:07pm

Hassan Sajedi

Updated 23-Jul-11 22:08pm

walterhevedeich

v2

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Comments

Uday P.Singh 24-Jul-11 4:27am

what error message are you getting?

3 solutions

Solution 1

Make sure the number of columns and the column names of your 2 tables are the same if you want it to work. You may want to specify the column names instead of putting *, like this.

SQL

SELECT fName, mName, lName FROM tblEmployeeInfo
UNION ALL
SELECT fName, mName, lName FROM tblStudentInfo

Posted 23-Jul-11 22:11pm

walterhevedeich

Comments

Abhinav S 24-Jul-11 4:17am

Good and precise answer. My 5.

walterhevedeich 24-Jul-11 4:23am

Thank you.

Hassan Sajedi 24-Jul-11 4:18am

My tables row numbers are not equal:
"SELECT id, Code, Title, Amount, PayType, PayDate, MaturityPayDate, UID, Description
FROM dbo.Orders_T
UNION ALL
SELECT id, Name, Amount, UID
FROM dbo.Domain_T"
Whether this is done? if is not to Implementation this query please send me another idea to done that.
thank you.

walterhevedeich 24-Jul-11 4:23am

You can't do a union with 2 tables that does not have the same number of columns and column names. Please don't get confused by the row numbers. The rows doesn't really matter, only the columns. Perhaps you might want to describe what you want to achieve here so we can better understand your problem.

Solution 2

You need to look at some of the basics of implementing a UNION clause - see here[^].

Posted 23-Jul-11 22:24pm

Abhinav S

Comments

walterhevedeich 24-Jul-11 4:25am

I believe this will be a great help to get OP educated about UNION. My 5.

Abhinav S 24-Jul-11 4:38am

Thank you Walter.

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Uday P.Singh · Accepted Answer · 2011-07-23T22:29:00

Solution 3

Before performing UNION operation must know this:

UNION RULES

1.A UNION must be composed of two or more SELECT statements, each separated by the keyword UNION.
2.Each query in a UNION must contain the same columns, expressions, or aggregate functions, and they must be listed in the same order.

3.Column datatypes must be compatible: They need not be the same exact same type, but they must be of a type that SQL Server can implicitly convert.

hope it helps :)

Posted 23-Jul-11 22:29pm

Uday P.Singh

Comments

Abhinav S 24-Jul-11 4:39am

My 5. Hope the OP is able to get going after going through all these answers.

Uday P.Singh 24-Jul-11 4:44am

thanks Abhinav :)

walterhevedeich 24-Jul-11 4:41am

5ed too

Uday P.Singh 24-Jul-11 4:44am

thanks walterhevedeich :)

uspatel 24-Jul-11 9:27am

these rules are very helpfull.

Sudhir Kumar Srivastava lko 25-Jul-11 8:37am

nice & conceptual answer my 5!