error in stored procedure

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error in stored procedure

ssurekha2000

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December 5, 2012 at 7:31 pm

#267794

ALTER PROCEDURE [dbo].[usp_delete] @tablename sysname, @pid int
,@pidname varchar(10)
AS
DECLARE @sql varchar(500)
SET @sql = 'delete from ' + @tablename + ' where '+ @pidname + ' = '+ @pid
Conversion failed when converting the nvarchar value 'delete from m_customer where cid = ' to data type int.
i get the above error
if i convert pid int to varchar i dont get error but the recod is not deleted
whts the best way toprevent sql injection and have database secured

Viewing 7 posts - 1 through 6 (of 6 total)

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WolfgangE SSCertifiable Points: 6328 More actions · Answer 1

To make your statement work you have to convert @pid in the string concatenation.

SET @sql = 'delete from ' + @tablename + ' where '+ @pidname + ' = '+ cast( @pid as varchar(50) )

To avoid sql injection you should not use dynamic statements like this at all. Write a separate delete procedure for every table where you want to delete data from.

kapil_kk SSC-Insane Points: 21316 More actions · Answer 2

first ensure that the value you are getting in @pid is int or varchar. If column data type is varchar then use CAST for it.

Hope, It will works for you 😛

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Sean Pearce SSCoach Points: 15999 More actions · Answer 3

ALTER PROCEDURE [dbo].[usp_delete]

@tablename sysname,

@pid int,

@pidname varchar(10)

AS

DECLARE @sql NVARCHAR(MAX),

@params NVARCHAR(MAX);

SELECT@sql = 'DELETE FROM [' + @tablename + '] WHERE ' + @pidname + ' = @pid;',

@params = '@pid INT';

EXEC sp_executesql @sql, @params, @pid = @pid;

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Eugene Elutin SSC Guru Points: 59322 More actions · Answer 4

Sean Pearce (12/11/2012)
ALTER PROCEDURE [dbo].[usp_delete] @tablename sysname, @pid int, @pidname varchar(10) AS DECLARE @sql NVARCHAR(MAX), @params NVARCHAR(MAX); SELECT@sql = 'DELETE FROM [' + @tablename + '] WHERE ' + @pidname + ' = @pid;', @params = '@pid INT';
EXEC sp_executesql @sql, @params, @pid = @pid;

Don't forget to test your sp by executing:

EXEC dbo].[usp_delete]

@tablename = 'sometable',

@pid int = 1,

@pidname = '1 = 1 OR 1 '

😎

It's a good idea to always protect your dynamic sql from injection

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Gail Shaw SSC Guru Points: 1004504 More actions · Answer 5

I strongly recommend you do not go this approach of generic delete procedures.

Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

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Sean Pearce SSCoach Points: 15999 More actions · Answer 6

Eugene Elutin (12/11/2012)
Sean Pearce (12/11/2012)
ALTER PROCEDURE [dbo].[usp_delete] @tablename sysname, @pid int, @pidname varchar(10) AS DECLARE @sql NVARCHAR(MAX), @params NVARCHAR(MAX); SELECT@sql = 'DELETE FROM [' + @tablename + '] WHERE ' + @pidname + ' = @pid;', @params = '@pid INT';
EXEC sp_executesql @sql, @params, @pid = @pid;
Don't forget to test your sp by executing:
EXEC dbo].[usp_delete]
@tablename = 'sometable',
@pid int = 1,
@pidname = '1 = 1 OR 1 '
😎
It's a good idea to always protect your dynamic sql from injection

You can offer some protection by wrapping the execution statement.