Error Handling in T-SQL

If ObjectProperty(Object_ID('dbo.dba_logError_sp'), N'IsProcedure') = 1
Begin
    Drop Procedure dbo.dba_logError_sp;
    Print 'Procedure dba_logError_sp dropped';
End;
Go
 
If ObjectProperty(Object_ID('dbo.dba_errorLog'), N'IsTable') Is Null
Begin
 
    Create Table dbo.dba_errorLog
    (         errorLog_id       int identity(1,1) 
            , errorType         char(3)     
                Constraint [DF_errorLog_errorType] Default 'sys' 
            , errorDate         datetime	
                Constraint [DF_errorLog_errorDate] Default(GetDate())
            , errorLine         int
            , errorMessage      nvarchar(4000)
            , errorNumber       int
            , errorProcedure    nvarchar(126)
            , procParameters    nvarchar(4000)
            , errorSeverity     int
            , errorState        int
            , databaseName      nvarchar(255)
        Constraint PK_errorLog_errorLogID Primary Key Clustered
        (
            errorLog_id	
        )
    );
 
    Print 'Table dba_errorLog created';
 
End;
Go
 
 
Set ANSI_Nulls On;
Set Ansi_Padding On;
Set Ansi_Warnings On;
Set ArithAbort On;
Set Concat_Null_Yields_Null On;
Set NoCount On;
Set Numeric_RoundAbort Off;
Set Quoted_Identifier On;
Go
 
Create Procedure dbo.dba_logError_sp
(
    /* Declare Parameters */
      @errorType            char(3)         = 'sys'
    , @app_errorProcedure   varchar(50)     = ''
    , @app_errorMessage     nvarchar(4000)  = ''
    , @procParameters       nvarchar(4000)  = ''
    , @userFriendly         bit             = 0
    , @forceExit            bit             = 1
    , @returnError          bit             = 1
)
As
/***************************************************************
    Name:       dba_logError_sp
 
    Author:     Michelle F. Ufford, http://sqlfool.com
 
    Purpose:    Retrieves error information and logs in the 
                        dba_errorLog table.
 
        @errorType = options are "app" or "sys"; "app" are custom 
                application errors, i.e. business logic errors;
                "sys" are system errors, i.e. PK errors
 
        @app_errorProcedure = stored procedure name, 
                needed for app errors
 
        @app_errorMessage = custom app error message
 
        @procParameters = optional; log the parameters that were passed
                to the proc that resulted in an error
 
        @userFriendly = displays a generic error message if = 1
 
        @forceExit = forces the proc to rollback and exit; 
                mostly useful for application errors.
 
        @returnError = returns the error to the calling app if = 1
 
    Called by:	Another stored procedure
 
    Date        Initials    Description
	----------------------------------------------------------------------------
    2008-12-16  MFU         Initial Release
****************************************************************
    Exec dbo.dba_logError_sp
        @errorType          = 'app'
      , @app_errorProcedure = 'someTableInsertProcName'
      , @app_errorMessage   = 'Some app-specific error message'
      , @userFriendly       = 1
      , @forceExit          = 1
      , @returnError        = 1;
****************************************************************/
 
Set NoCount On;
Set XACT_Abort On;
 
Begin
 
    /* Declare Variables */
    Declare	@errorNumber            int
            , @errorProcedure       varchar(50)
            , @dbName               sysname
            , @errorLine            int
            , @errorMessage         nvarchar(4000)
            , @errorSeverity        int
            , @errorState           int
            , @errorReturnMessage   nvarchar(4000)
            , @errorReturnSeverity  int
            , @currentDateTime      smalldatetime;
 
    Declare @errorReturnID Table (errorID varchar(10));
 
    /* Initialize Variables */
    Select @currentDateTime = GetDate();
 
    /* Capture our error details */
    If @errorType = 'sys' 
    Begin
 
        /* Get our system error details and hold it */
        Select 
              @errorNumber      = Error_Number()
            , @errorProcedure   = Error_Procedure()
            , @dbName           = DB_Name()
            , @errorLine        = Error_Line()
            , @errorMessage     = Error_Message()
            , @errorSeverity    = Error_Severity()
            , @errorState       = Error_State() ;
 
    End
    Else
    Begin
 
    	/* Get our custom app error details and hold it */
        Select 
              @errorNumber      = 0
            , @errorProcedure   = @app_errorProcedure
            , @dbName           = DB_Name()
            , @errorLine        = 0
            , @errorMessage     = @app_errorMessage
            , @errorSeverity    = 0
            , @errorState       = 0 ;
 
    End;
 
    /* And keep a copy for our logs */
    Insert Into dbo.dba_errorLog
    (
          errorType
        , errorDate
        , errorLine
        , errorMessage
        , errorNumber
        , errorProcedure
        , procParameters
        , errorSeverity
        , errorState
        , databaseName
	)
    OutPut Inserted.errorLog_id Into @errorReturnID
    Values
    (
          @errorType
        , @currentDateTime
        , @errorLine
        , @errorMessage
        , @errorNumber
        , @errorProcedure
        , @procParameters
        , @errorSeverity
        , @errorState
        , @dbName
    );
 
    /* Should we display a user friendly message to the application? */
    If @userFriendly = 1
        Select @errorReturnMessage = 'An error has occurred in the database (' + errorID + ')'
        From @errorReturnID;
    Else 
        Select @errorReturnMessage = @errorMessage;
 
    /* Do we want to force the application to exit? */
    If @forceExit = 1
        Select @errorReturnSeverity = 15
    Else
        Select @errorReturnSeverity = @errorSeverity;
 
    /* Should we return an error message to the calling proc? */
    If @returnError = 1
        Raiserror 
        (
              @errorReturnMessage
            , @errorReturnSeverity
            , 1
        ) With NoWait;
 
    Set NoCount Off;
    Return 0;
 
End
Go

Begin Try
 
    /* If a business logic error exists, then call this proc */
    If 1 != 1
        Execute dbo.dba_logError_sp 
              @errorType            = 'app'
            , @app_errorProcedure   = 'yourStoredProcedureName'
            , @app_errorMessage     = '1 does not equal 1!'
            , @forceExit            = 1;
 
    /* Start a new transaction */
    Begin Transaction;  
 
    /* Do something */
 
    /* If you have an open transaction, commit it */
    If @@TranCount > 0
        Commit Transaction;
 
End Try
Begin Catch
 
    /* Whoops, there was an error... rollback! */
    If @@TranCount > 0
        Rollback Transaction;
 
    /* Grab our proc parameters */
    Set @errorParameters = '@myVariable = ' + @myVariable;
 
    /* Return an error message and log it */
    Execute dbo.dba_logError_sp
        @procParameters = @errorParameters;
 
End Catch;