SQL checks whether the database, table, stored procedure, and other codes exist.

Check whether SQL exists
-- Determine whether the database exists
If exists (select * from master .. sysdatabases where name = N 'database name ')
Print 'exists'
Else
Print 'not exists'

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-- Determine whether the table name to be created exists
If exists (select * from dbo. sysobjects where id = object_id (n' [dbo]. [Table name] ') and OBJECTPROPERTY (id, n'isusertable') = 1)
-- Delete a table
Drop table [dbo]. [table name]
GO

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-- Determine whether the temporary table to be created exists
If Object_Id ('tempdb. dbo. # test') Is Not Null
Begin
Print 'exist'
End
Else
Begin
Print 'nonexistent'
End

---------------
-- Determine whether the stored procedure name to be created exists
If exists (select * from dbo. sysobjects where id = object_id (n' [dbo]. [stored procedure name] ') and OBJECTPROPERTY (id, n' IsProcedure') = 1)
-- Delete a stored procedure
Drop procedure [dbo]. [stored procedure name]
GO

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-- Determine whether the view name to be created exists
If exists (select * from dbo. sysobjects where id = object_id (n' [dbo]. [view name] ') and OBJECTPROPERTY (id, n'isview') = 1)
-- Delete View
Drop view [dbo]. [view name]
GO

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-- Determine whether the name of the function to be created exists
If exists (select * from dbo. sysobjects where id = object_id (n' [dbo]. [function name] ') and xtype in (n'fn', n'if', n'tf '))
-- Delete a function
Drop function [dbo]. [function name]
GO

If col_length ('table name', 'column name') is null
Print 'nonexistent'

Select 1 from sysobjects where id in (select id from syscolumns where name = 'column name') and name = 'table name'