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Max function

Author

Topic

kio
Starting Member

1 Post

Posted - 2009-03-17 : 17:28:52

Hi at all,
i'm new user of this forum
I have this problem
My windows application is a multi-user application on same database sql-server
Inside my database there are 3 tables with a same field (FIELD_A).

Field_A is integer (INT)

Users can insert record inside table_A, table_B, table_C but when insert record i must get
max value from table_A, table_B, table_C , how can i do ?

Then, if i get max value from table_A, table_B, table_C is there possible that another user can get
same max value, before i insert record inside table_A or table_B or table_C ?

Note: Max value must be unique for table_A, table_B, table_C simultaneously

Thank you very much

SwePeso
Patron Saint of Lost Yaks

30421 Posts

Posted - 2009-03-18 : 03:48:57

You can use transactions. Or set a proper ISOLATION LEVEL.

DECLARE	@Max INT

BEGIN TRANSACTION

SELECT	@Max = MAX(Field_A)
FROM	(
		SELECT	MAX(Field_A)
		FROM	Table1

		UNION ALL

		SELECT	MAX(Field_A)
		FROM	Table2

		UNION ALL

		SELECT	MAX(Field_A)
		FROM	Table3		
	) AS f

... Now do something

COMMIT TRANSACTION

E 12°55'05.63"
N 56°04'39.26"

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