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delete rows

Author

Topic

laddu
Constraint Violating Yak Guru

332 Posts

Posted - 2011-05-21 : 15:09:27

Hi,

I am trying to delete a row in parents and related child tables data.

I used below stored proc, but it's throwing error after crossing 32 nested. Please guide me, i need to delete around 10 parent rows. Thanks!

error:
Msg 217, Level 16, State 1, Procedure spDeleteRows, Line 58
Maximum stored procedure, function, trigger, or view nesting level exceeded (limit 32).

CREATE Procedure spDeleteRows
/*
Recursive row delete procedure.

It deletes all rows in the table specified that conform to the criteria selected,
while also deleting any child/grandchild records and so on. This is designed to do the
same sort of thing as Access's cascade delete function. It first reads the sysforeignkeys
table to find any child tables, then deletes the soon-to-be orphan records from them using
recursive calls to this procedure. Once all child records are gone, the rows are deleted
from the selected table. It is designed at this time to be run at the command line. It could
also be used in code, but the printed output will not be available.
*/
(
@cTableName varchar(50), /* name of the table where rows are to be deleted */
@cCriteria nvarchar(1000), /* criteria used to delete the rows required */
@iRowsAffected int OUTPUT /* number of records affected by the delete */
)
As
set nocount on
declare @cTab varchar(255), /* name of the child table */
@cCol varchar(255), /* name of the linking field on the child table */
@cRefTab varchar(255), /* name of the parent table */
@cRefCol varchar(255), /* name of the linking field in the parent table */
@cFKName varchar(255), /* name of the foreign key */
@cSQL nvarchar(1000), /* query string passed to the sp_ExecuteSQL procedure */
@cChildCriteria nvarchar(1000), /* criteria to be used to delete
records from the child table */
@iChildRows int /* number of rows deleted from the child table */

/* declare the cursor containing the foreign key constraint information */
DECLARE cFKey CURSOR LOCAL FOR
SELECT SO1.name AS Tab,
SC1.name AS Col,
SO2.name AS RefTab,
SC2.name AS RefCol,
FO.name AS FKName
FROM dbo.sysforeignkeys FK
INNER JOIN dbo.syscolumns SC1 ON FK.fkeyid = SC1.id
AND FK.fkey = SC1.colid
INNER JOIN dbo.syscolumns SC2 ON FK.rkeyid = SC2.id
AND FK.rkey = SC2.colid
INNER JOIN dbo.sysobjects SO1 ON FK.fkeyid = SO1.id
INNER JOIN dbo.sysobjects SO2 ON FK.rkeyid = SO2.id
INNER JOIN dbo.sysobjects FO ON FK.constid = FO.id
WHERE SO2.Name = @cTableName

OPEN cFKey
FETCH NEXT FROM cFKey INTO @cTab, @cCol, @cRefTab, @cRefCol, @cFKName
WHILE @@FETCH_STATUS = 0
BEGIN
/* build the criteria to delete rows from the child table. As it uses the
criteria passed to this procedure, it gets progressively larger with
recursive calls */
SET @cChildCriteria = @cCol + ' in (SELECT [' + @cRefCol + '] FROM [' +
@cRefTab +'] WHERE ' + @cCriteria + ')'
print 'Deleting records from table ' + @cTab
/* call this procedure to delete the child rows */
EXEC spDeleteRows @cTab, @cChildCriteria, @iChildRows OUTPUT
FETCH NEXT FROM cFKey INTO @cTab, @cCol, @cRefTab, @cRefCol, @cFKName
END
Close cFKey
DeAllocate cFKey
/* finally delete the rows from this table and display the rows affected */
SET @cSQL = 'DELETE FROM [' + @cTableName + '] WHERE ' + @cCriteria
print @cSQL
EXEC sp_ExecuteSQL @cSQL
print 'Deleted ' + CONVERT(varchar, @@ROWCOUNT) + ' records from table ' + @cTableName

--delete a row, example
exec spDeleteRows 'X', 'field1 = ''234''', 0

jfarrugia
Yak Posting Veteran

55 Posts

Posted - 2011-05-22 : 04:28:33

It seems that the number of nested calls exceeds 32 which is the limit. I suggest tracking the depth and reducing the nested calls to below 32.. if the SP calls itself, it is considered a nest - so take that into account.

Hope this helps.

Where software development knowledge meets the reader

jfarrugia
Yak Posting Veteran

55 Posts

Posted - 2011-05-22 : 04:31:21

Or.. if you're using foreign keys (referential integrity amongst tables).. you can apply a cascade delete option without the use of a complicated nested SP.

CREATE TABLE test_child
(SUB1 INT,
[NO] int,
FOREIGN KEY ([NO]) REFERENCES Test_parent
ON DELETE CASCADE)

Where software development knowledge meets the reader

aravindt77
Posting Yak Master

120 Posts

Posted - 2011-05-23 : 04:35:22

still if you have already created the table without cascading and fed data into it..no probs... by modifying the table defintion thru the management studio console ..will be able to specify the cascading if necessary and avoid fur ther nesting .. you need only to delete the parent rows.. sql server will automatically remove its rows which are of dependend on it.

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