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IF OBJECT_ID - Why is this line always used when creating tables

  • July 3, 2015 at 11:43 pm

    #299726

    Hi guys,

    I am currently going through T-SQL examples as I am still learning SQL, please can someone tell me why we use the following line below all the time when creating tables? Also what does the 'N' mean? Also what 'OBJECT_ID' is it looking for?

    IF OBJECT_ID(N'Sales.MyOrders', N'U')IS NOT NULL DROP TABLE Sales.My.Orders;

    Thank you in Advance

  • July 4, 2015 at 12:16 am

    #1810265

    General purpose of it is to return object ID based on given name but we use it to check if the object already exists or not before we attempt to drop it or create it. If OBJECT_ID will return NULL for an object name that means it does not exists and vice versa.

    N'some string here' - this N next to the string enclosed in single quotes mean that the string is NVARCHAR type if N wouldn't be there it would be VARCHAR

    IF OBJECT_ID('TestTable', 'U') IS NOT NULL

    DROP TABLE TestTable

    SELECT N'test string' as ntest, 'test string' test INTO TestTable

    SELECT OBJECT_ID('TestTable') ObjectID, OBJECT_NAME(OBJECT_ID('TestTable')) ObjectName

    EXEC sp_help 'TestTable'

    IF OBJECT_ID(N'TestTable', N'U') IS NOT NULL

    DROP TABLE TestTable

  • July 5, 2015 at 6:41 am

    #1810314

    Many Thanks for your reply

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