Friday, September 28, 2012

Sybase to SQL Server Migration Issues

Variable Scope/behavior in Update statment:

                   In Sybase intermediate calculation with variable for the update statement,Variable value is based on last executed statement or last executed record.In Sybase,variable updation will happen after the column updation.Which means the updation in variable has low priority when compare with the updation in column  for the single update statement.If we think the output of the updated variable want to become the input of the column updation for each and every row,we cannot attain in Sybase.Because the update in column will execute first and then update in variable execute in single update statement even we placed left or right side.

But in SQL Server we can perform the above operation.The variables are highly dynamic and record dependent.The priority for the variable updation is in high priority.So we can get consistent result.

If you see the below given screenshots you can understand the scenario
which i am trying to explain.

Variable behavior in Sybase Update statement

Variable behavior in SQL Server Update statement

             I just shared the difference between two technologies for the update statement while using intermediate variable.Hopefully we won't get such a scenario from Source.

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