Unique index exception

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Hi,

I am trying to catch the system generated unique key exception and I want to throw my own message.

I am doing it in Visual Studio 2008

I am using the following code. In my application code just before inserting i am using this code.

VB

Try
            l_Database.gp_BeginTransaction()
            ls_SqlStr = "SELECT * FROM  mst_country where cn_sid = po_Country.cn_sid"

        Catch ex As SqlException
            Throw ex
        Finally
            l_Database.gp_CloseConnection()
            l_Database = Nothing
        End Try

And in my business logic layer I am trying to write my own message by calling this exception.

But I am not sure whether I am doing correctly or not.

Please can any body suggest me to fix this and work efficiently.

Regards
Srikar

Posted 7-Dec-09 9:28am

Saisrikar1982

Updated 8-Dec-09 10:59am

Sean Ewington

v2

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Sriram K G · Answer 1 · 2009-12-08T01:51:00

Hi,

Please avoid catching and throwing it.
If you any logics inside catch, then its fine.
Just catching and throwing the exception back doesn't add a value
and tis expensive too..

Instead think of the following code:

Try
l_Database.gp_BeginTransaction()
ls_SqlStr = "SELECT * FROM mst_country where cn_sid = po_Country.cn_sid"

Finally
l_Database.gp_CloseConnection()
l_Database = Nothing
End Try

Here the catch block is removed and the same is handled in the business logic layer..

Your business logic layer looks like:

try
{
//call the funtion above..
}
catch(SqlException ex)
{
bool hasOtherErrors = false;
//The batch statments will have a collection of errors and there are possibilites
//where you will get other errors like foriegn key..In that case you should throw the
//error back if its not a unique constratint error.
foreach(SqlError er in ex.Errors)
{
//parse each and every sqlerror and identify if its a unique contraint error.
if(er.ErrorNumber == UNIQUE_CONSTRAINT_ERROR_NO)
{
//show your customized error message here....
}
else
{
//If it has any other error other than a UniqueConstraint error..
hasOtherErrors = true;
}
}//for each

if(hasOtherErrors)
{
//rethrow the error since we have other errors in the bathc statement
//Also use throw to preserve stack trace
throw;
}
}//cathc