SQL SERVER – Insert Multiple Records Using One Insert Statement – Use of UNION ALL

June 8, 2007

Update: In SQL Server 2008 there is an even better method of Row Construction for inserting multiple records, please read it here: SQL SERVER Insert Multiple Records Using One Insert Statement – Use of Row Constructor

This is a very interesting question I have received from new development. How can I insert multiple values in a table using only one insert? Now this is an interesting question. When there are multiple records are to be inserted in the table following is the common way using T-SQL.

SQL SERVER - Insert Multiple Records Using One Insert Statement - Use of UNION ALL fullouter_join

USE YourDB
GO
INSERT INTO MyTable  (FirstCol, SecondCol)
        VALUES ('First',1);
INSERT INTO MyTable  (FirstCol, SecondCol)
        VALUES ('Second',2);
INSERT INTO MyTable  (FirstCol, SecondCol)
        VALUES ('Third',3);
INSERT INTO MyTable  (FirstCol, SecondCol)
        VALUES ('Fourth',4);
INSERT INTO MyTable  (FirstCol, SecondCol)
        VALUES ('Fifth',5);
GO

The clause INSERT INTO is repeated multiple times. Many times DBA copy and paste it to save time. There is another alternative to this, which I use frequently. I use UNION ALL and INSERT INTO … SELECT… Clauses. Regarding performance there is not much difference. If there is performance difference it does not matter as I use this for one time insert script. I enjoy writing this way, as it keeps my focus on the task, instead of copy paste. I have explained following script to new developers. He was quite pleased.

USE YourDB
GO
INSERT INTO MyTable (FirstCol, SecondCol)
SELECT 'First' ,1
UNION ALL
SELECT 'Second' ,2
UNION ALL
SELECT 'Third' ,3
UNION ALL
SELECT 'Fourth' ,4
UNION ALL
SELECT 'Fifth' ,5
GO

The effective result is same.

Reference : Pinal Dave (https://blog.sqlauthority.com) , SQL SERVER – Union vs. Union All – Which is better for performance?