BI SQL # 147 : SQL Server DBA Scripts : Delete rows from relational tables with foreign keys
Hi Friends,
In this article we are going to cover How to Delete rows from relational tables with foreign keys.
In this post we are going to discuss following points:
- Problem Statement of SQL Script:
- Description of SQL Script:
- SQL Script Code
- SQL Script Output Screenshot
- User Level to execute
Problem Statement of SQL Script:
Delete rows from relational tables with foreign keys.
Description of SQL Script:
This T-SQL Script will give the tree structure, so the output of this procedure you can use to delete or insert or update the keys.
SQL Script Code
ALTER PROCEDURE pr_schema AS SET NOCOUNT ON -- 1 SELECT SCHEMA_NAME(SOF.SCHEMA_ID) AS FSC_NAME ,T1.FKEYID AS FK ,SCHEMA_NAME(SOR.SCHEMA_ID) AS RSC_NAME ,T1.RKEYID AS PK INTO #sysref FROM sysforeignkeys T1 LEFT OUTER JOIN sys.objects SOF ON SOF.OBJECT_ID = T1.FKEYID LEFT OUTER JOIN sys.objects SOR ON SOR.OBJECT_ID = T1.RKEYID -- below 3 lines is to avoid the problems with self reference LEFT OUTER JOIN SYSREFERENCES T2 ON OBJECT_NAME(T1.FKEYID) + OBJECT_NAME(T1.RKEYID) = OBJECT_NAME(T2.RKEYID) + OBJECT_NAME(T2.FKEYID) WHERE T2.FKEYID IS NULL --******************************************************* -- Get the Max No.Of Joins foreign keys in a Chain DECLARE @N VARCHAR(9); WITH CTE ( FKEYID ,LEVEL ) AS ( SELECT FKEYID ,0 FROM sysforeignkeys UNION ALL SELECT T1.PK ,LEVEL + 1 FROM #sysref T1 JOIN CTE T2 ON T1.FK = T2.FKEYID ) -- Statement that executes the CTE SELECT @N = Max(LEVEL) FROM CTE PRINT @N --******************************************************* DECLARE @V1 VARCHAR(max) SET @V1 = '' DECLARE @V2 VARCHAR(max) SET @V2 = '' DECLARE @select VARCHAR(max) SET @select = '' DECLARE @OrderBy VARCHAR(2) SET @OrderBy = @N + 1 WHILE NOT @N = 0 BEGIN SET @V1 = @V1 + ' right outer join #sysref A' + cast(@N AS VARCHAR(4)) + ' on a' + @V2 + '.pk =A' + cast(@N AS VARCHAR(4)) + '.fk' SET @select = @select + 'a' + @N + '.FSC_NAME+''.''+object_name(' + 'a' + @N + '.fk) AS key' + convert(VARCHAR, (@N + 1 )) + ',' SET @V2 = @N SET @N = @N - 1 CONTINUE END SET @select = @select + 'A1.RSC_NAME+''.''+object_name(A1.PK) AS Key1' EXEC ( 'SELECT ' + @select + ' from #sysref a ' + @V1 + ' order by ' + @OrderBy )
SQL Script Output Screenshot
User Level to execute
- 400
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