Programmatically rename all system name constraints - sql

Question

I have a distributed application that lives at many customer sites. The previous developer was not very good in giving user defined names to constraints. How could I go about renaming all the constrains to something like 'DF_[TableName]_[ColumnName]'? I could try and cursor over the list of tables. Do you think this would be a problem if I deploy this to a customer site? Or is there a better way to accomplish this?
SELECT sys.schemas.name as [Schema],
sys.tables.name as [TableName],
sys.all_columns.name as [Column],
default_constraints.name as [Constraint]
FROM
sys.all_columns
INNER JOIN sys.tables
ON all_columns.object_id = tables.object_id
INNER JOIN sys.schemas
ON tables.schema_id = schemas.schema_id
INNER JOIN sys.default_constraints
ON all_columns.default_object_id = default_constraints.object_id
where default_constraints.name like '%[0-9]%'

Answer 1

If you are using a naming convention for each constraint type, then this would help you. Here I am putting an example of how to handle this with Default constraint. The procedure will find default constraints, drop those that don't follow naming conventions and create new ones with the old one's definition.
This is a simple version for one time run
DECLARE #SchemaName sysname = 'dbo';
DECLARE #TableName sysname = NULL;
DECLARE #ColumnName sysname = NULL;
DECLARE #sql VARCHAR(max) = '';
SELECT
#sql +=
'ALTER TABLE [' + s.name + '].[' + o.name + '] DROP CONSTRAINT [' + dc.name + ']; ' +
'ALTER TABLE [' + s.name + '].[' + o.name + '] ADD CONSTRAINT [DF_' + o.name + '_' + c.name + '] DEFAULT ' + dc.DEFINITION + ' FOR [' + c.name + '];'
FROM dbo.sysobjects do
INNER JOIN dbo.sysobjects o ON do.parent_obj = o.id
INNER JOIN sys.default_constraints dc ON dc.object_id = do.id
INNER JOIN sys.columns c ON c.object_id = o.id
AND c.column_id = dc.parent_column_id
INNER JOIN sys.schemas s ON s.schema_id = dc.schema_id
WHERE o.type = 'U'
AND do.type = 'D'
AND s.name = #SchemaName
AND o.name = CASE WHEN ISNULL(#TableName,'') = ''
THEN o.name
ELSE #TableName END
AND c.name = CASE WHEN ISNULL(#ColumnName,'') = ''
THEN c.name
ELSE #ColumnName END
AND do.name NOT LIKE 'DF_' + o.name + '_' + c.name
ORDER BY o.name
--PRINT (#sql)
EXECUTE(#sql)
And this is a procedure in case you want to keep running the procedure every once in a while
USE [YourDatabaseName]
GO
-- Check if the procedure exists and drop it if so
IF EXISTS (SELECT *
FROM sys.objects
WHERE object_id = OBJECT_ID(N'[dbo].[usp_NamingConventionDefaultConstraint]') AND type in (N'P', N'PC'))
DROP PROCEDURE [dbo].[usp_NamingConventionDefaultConstraint]
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
--procedure can be used for specific schema/table/columns or those can be left null to include everything.
CREATE PROC [dbo].[usp_NamingConventionDefaultConstraint]
#SchemaName sysname = 'dbo',
#TableName sysname = NULL,
#ColumnName sysname = NULL
AS
BEGIN
SET NOCOUNT ON;
DECLARE #sql VARCHAR(max)
DECLARE GetIndexes CURSOR
FOR
SELECT
--here drop the old constraint and create a new one with the old's definition
'ALTER TABLE [' + s.name + '].[' + o.name + '] DROP CONSTRAINT [' + dc.name + ']; ' +
'ALTER TABLE [' + s.name + '].[' + o.name + '] ADD CONSTRAINT [DF_' + o.name + '_' + c.name + '] DEFAULT ' + dc.DEFINITION + ' FOR [' + c.name + '];'
AS dc_alter
FROM dbo.sysobjects do
INNER JOIN dbo.sysobjects o ON do.parent_obj = o.id
INNER JOIN sys.default_constraints dc ON dc.object_id = do.id
INNER JOIN sys.columns c ON c.object_id = o.id
AND c.column_id = dc.parent_column_id
INNER JOIN sys.schemas s ON s.schema_id = dc.schema_id
WHERE o.type = 'U'
-- work only on default constraints
AND do.type = 'D'
AND s.name = #SchemaName
AND o.name = CASE WHEN ISNULL(#TableName,'') = '' THEN o.name ELSE #TableName END
AND c.name = CASE WHEN ISNULL(#ColumnName,'') = '' THEN c.name ELSE #ColumnName END
-- here goes the naming convention you have in mind
--DF_TableName_ColumnName
AND do.name NOT LIKE 'DF_' + o.name + '_' + c.name
ORDER BY o.name
OPEN GetIndexes
FETCH NEXT FROM GetIndexes
INTO #sql
WHILE ##FETCH_STATUS = 0
BEGIN
IF ISNULL(#sql,'')<>''
BEGIN
EXEC (#sql)
END
FETCH NEXT FROM GetIndexes
INTO #sql
END
CLOSE GetIndexes
DEALLOCATE GetIndexes
END
GO