Exceptions in SQL Server
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1. There are three types of errors that can occur in programs: compilation errors, logical errors, and runtime errors. Runtime errors are called exceptions. 2. In older versions of SQL Server, the @@ERROR predefined variable was used to handle exceptions. In newer versions, a TRY-CATCH block is used instead. 3. The TRY block contains statements that may cause runtime errors. If an error occurs, control passes to the CATCH block, which can rectify or manage the error.
Exceptions in SQL Server
- 1. EXCEPTIONS: 1. In programs 3 types of error will occur. They are compilation errors, logical errors and runtime errors 2. Compilation errors and logical errors can be rectified or managed by the programmer 3. Runtime error will manage or rectified by using exception. 4. Runtime errors are called exceptions.in SQLSERVER 2000 and OLD versions @@ERROR predefined global variable is used. 5. In sqlserver 2005 & in next versions try-catch block will be used. SYNTAX: BEGIN TRY STATEMENT(S) END TRY BEGIN CATCH STATEMENT(S) END CATCH NOTE: 1. All the statements will be in try block when runtime occurs try block will through error to the catch block 2. Catch block will rectify the error or it will manage the error so that program can run successfully Example CREATE PROCEDURE PRCDIV @A INT,@B INT AS BEGIN BEGIN TRY DECLARE @C INT PRINT @C=@A/@B PRINT @C END TRY
- 2. BEGIN CATCH SELECT ERROR_NUMBER(),ERROR_MESSAGE() END CATCH END NOTE: ERROR_NUMBER() and ERROR_MESSAGE() are used to display system error number and system error message CREATE PROCEDURE TO CHECK WHETHER THE GIVEN TABLE IS EXISTING OR NOT CREATE PROCEDURE PRC2 AS BEGIN BEGIN TRY DECLARE @S NVARCHAR(100) SELECT @S=’SELECT * FROM EMPLOYEE’ EXEC SP_EXECUTE SQL@S END TRY BEGIN CATCH SELECT ERROR_NUMBER() NUMBER ERROR_MESSAGE() MESSAGE END CATCH END