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@LitKnd
Created June 16, 2020 12:10
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SET QUOTED_IDENTIFIER ON;
GO
SET ANSI_NULLS ON;
GO
/*******************************************
The code for this function contains extra steps, because SQL Server
does not allow you to alter a function if it is referenced by a default constraint
******************************************/
/*******************************************
1. Identify default constraints on tables which reference this function
Store commands to drop and recreate those functions in a table
Note: SQL Server does not allow you to create a default constraint with a system name
in an ALTER TABLE ADD CONSTRAINT statement like this, so this script has a side-effect
of turning system-named default constraints into user-named default constraints (using what is
present in the database as the hard coded name)
******************************************/
DROP TABLE IF EXISTS #manageconstraints;
GO
SELECT N'ALTER TABLE ' + s.name + N'.[' + t.name + N'] DROP CONSTRAINT ' + d.name AS drop_command,
N'ALTER TABLE ' + s.name + N'.[' + t.name + N'] ADD CONSTRAINT ' + d.name + N' DEFAULT ' + d.definition
+ N' for ' + c.name AS create_command
INTO #manageconstraints
FROM sys.tables t
JOIN sys.schemas AS s
ON t.schema_id = s.schema_id
JOIN sys.default_constraints d
ON d.parent_object_id = t.object_id
JOIN sys.columns c
ON c.object_id = t.object_id
AND c.column_id = d.parent_column_id
WHERE t.name NOT IN ( '__MigrationLog', '__SchemaSnapshot' );
/*******************************************
2. Drop default constraints before altering function
******************************************/
DECLARE @command NVARCHAR(MAX);
DECLARE drop_constraints CURSOR FAST_FORWARD LOCAL READ_ONLY FOR
SELECT drop_command
FROM #manageconstraints;
OPEN drop_constraints;
FETCH NEXT FROM drop_constraints
INTO @command;
WHILE @@FETCH_STATUS = 0
BEGIN
PRINT @command;
EXEC sp_executesql @command;
FETCH NEXT FROM drop_constraints
INTO @command;
END;
CLOSE drop_constraints;
DEALLOCATE drop_constraints;
GO
/*******************************************
3. Recreate the function
******************************************/
CREATE OR ALTER FUNCTION [dbo].[IMAUDF]
()
RETURNS DATETIME2(0)
AS
BEGIN
DECLARE @return DATETIME2(0);
SET @return = SYSDATETIME();
RETURN @return;
END;
GO
/*******************************************
4. Recreate default constraints referencing this function
******************************************/
DECLARE @command NVARCHAR(MAX);
DECLARE create_constraints CURSOR FAST_FORWARD LOCAL READ_ONLY FOR
SELECT create_command
FROM #manageconstraints;
OPEN create_constraints;
FETCH NEXT FROM create_constraints
INTO @command;
WHILE @@FETCH_STATUS = 0
BEGIN
PRINT @command;
EXEC sp_executesql @command;
FETCH NEXT FROM create_constraints
INTO @command;
END;
CLOSE create_constraints;
DEALLOCATE create_constraints;
GO
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