SQL Framework

SQL Framework

INTRODUCTION

Developers who have experienced large application development know the necessities of framework. In this regard, more experienced developers like Team Lead, Technical Lead and Project Manager up to CTO have high respect for it. They know from their experience that large applications should develop in a very organized way so that newly assigned developers take little time to adopt the development structure behind the application and take less costly man hour form Team Lead or other senior developers. They also know that maintenance will be easy and cost effective after development has been completed for the application.

BACKGROUND

Apart from this, I will be going through developing a SQL Framework. I will show the necessity of it with demonstration.

LET’S GET STARTED

• Open SQL Management Studio

I want to start by designing a table structure in SQL Management Studio as shown below:

Figure 1

Say you are working in a large software company for a big project and will take a long time. You have many programmers working under you in this project. Sometimes, programmers are switching from your software company and are replaced by new programmers. So far, this is a big project so underlining database size will be accordingly big. Say, you have assigned a task to a programmer to create a stored procedure for data insertion with proper validation and other necessary command in store procedure.

The below procedure has been created by the programmer as his assigned task.

Hide   Shrink    Copy Code

CREATE PROCEDURE [dbo].[Customer_Set]
 @Name as varchar(50),
     @Address as varchar(250),    
 @Mobile as varchar(50)
AS
BEGIN

 SET NOCOUNT ON

 --Validation
 IF @Name IS NULL
 BEGIN
  RAISERROR ('Name cannot be empty.',16,1)
 END

 IF LEN(@Name)<3
 BEGIN
  RAISERROR ('Name cannot be less than 3 characters.',16,1)
 END 

 --Data Insertion
 BEGIN TRY
  INSERT INTO [dbo].[Customer]
   ([Name]
   ,[Address]
   ,[Mobile])
  VALUES
   (@Name
   ,@Address   
   ,@Mobile)
 END TRY
 BEGIN CATCH
  RETURN (0)
 END CATCH

 RETURN (1)
END

You have also assigned another developer to write a stored procedure for supplier table.

Figure 2

Then write stored procedure like below:

Hide   Shrink    Copy Code

CREATE PROCEDURE [dbo].[Supplier_Set]
@Name as varchar(50),
@Address as varchar(250),    
@Mobile as varchar(50)
AS
BEGIN

 SET NOCOUNT ON

 --Validation
 IF @Name IS NULL
 BEGIN
  RAISERROR ('Please enter supplier name.',16,1)
 END

 IF LEN(@Name)<3
 BEGIN
  RAISERROR ('Supplier name cannot be less than 3 characters.',16,1)
 END 

 --Data Insertion
 BEGIN TRY
  INSERT INTO [dbo].[Supplier]
   ([Name]
   ,[Address]
   ,[Mobile])
  VALUES
   (@Name
   ,@Address   
   ,@Mobile)
 END TRY
 BEGIN CATCH
  RETURN (-1)
 END CATCH

 RETURN (1)
END

While reviewing code for the above two stored procedures written by two programmers, you will find the following difference:

Hide   Copy Code

IF @Name IS NULL
BEGIN
RAISERROR ('Name cannot be empty.',16,1)
END

IF LEN(@Name)<3
BEGIN
RAISERROR ('Name cannot be less than 3 characters.',16,1)
END 

BEGIN CATCH
  RETURN (0)
 END CATCH
 RETURN (1)

Another programmer:

Hide   Copy Code

IF @Name IS NULL
BEGIN
RAISERROR ('Please enter supplier name.',16,1)
END

IF LEN(@Name)<3
BEGIN
RAISERROR ('Supplier name cannot be less than 3 characters.',16,1)
END 

BEGIN CATCH
  RETURN (-1)
 END CATCH

 RETURN (1)

So one programmer writes:

1. Name cannot be empty
2. Name cannot be less than 3 characters
3. RETURN (0)

Another programmer writes:

1. Please enter supplier name
2. Supplier name cannot be less than 3 characters
3. RETURN (-1)

For the same kind of work, they have not used similar messages and they have also return 0 and -1 which are not understandable. And other developers may write something other than this. So this system is not a generic system or not followed by the same structure.

It will be very tough to manage if you have a large number of stored procedures like the above written by many developers.

System should develop followed by a structure that I called framework and all messages should have a common, return type that should be readable and other things regarding a structure should be common. That will help us to manage system easily and by using less effort.

We can build a framework by writing some additional stored procedures in this case and you can increase as your requirement to build your own.

Let's create a stored procedure to set some constant variables most likely as Enum in .NET. These constants will actually be used in other regular procedure for different type of operation. These constants are for common system development.

Hide   Copy Code

CREATE PROCEDURE [dbo].[GetValidationConstraint]
 --Output values
 @EmptyCheck int OUTPUT,
 @LenCheck int  =NULL OUTPUT,
 @NoDataExist int =NULL OUTPUT,
 @True bit =NULL OUTPUT, 
 @False bit =NULL OUTPUT
AS
BEGIN
 SELECT @EmptyCheck=1
 SELECT @LenCheck =2
 SELECT @NoDataExist =3

 SELECT @True=1 
 SELECT @False=0
END

Another procedure is for common return message for the whole application.

Hide   Copy Code

CREATE PROCEDURE [dbo].[ReturnMessage]
 --Success, Fail is the order of output parameter
 @Success int OUTPUT, 
 @Fail int OUTPUT 
AS
SET NOCOUNT ON

BEGIN
 SELECT @Fail=0
 SELECT @Success=1  
END

The below procedure is for common messages for the application:

Hide   Shrink    Copy Code

CREATE PROCEDURE [dbo].[MessageHelper]
 --Input values
 @Field varchar(200) =NULL,
 @MinLenght int =NULL,
 @ValidationConstraint int,
 --Output values
 @ValidationMessage varchar(200) OUTPUT 
AS
BEGIN
 --Variables
 DECLARE @EMPTY_MESSAGE varchar(50),
  @MINIMUM_LENGHT_MESSAGE varchar(50),
  @NO_DATA_EXIST_MESSAGE varchar(50)

 DECLARE @EMPTY int,
  @LEN int,
  @NO_DATA_EXIST int 

 DECLARE @SUCCESSED int,
  @FAILED int 

 --Message Constraint
 SET @EMPTY_MESSAGE = 'cannot be empty.'
 SET @MINIMUM_LENGHT_MESSAGE ='cannot be less than'
 SET @NO_DATA_EXIST_MESSAGE = 'No record found.'
 
 --Get global values
 EXEC ReturnMessage @SUCCESSED output, @FAILED output
 EXEC GetValidationConstraint @EMPTY OUTPUT, @LEN OUTPUT, @NO_DATA_EXIST OUTPUT

 --Set message
 IF @ValidationConstraint = @EMPTY 
 BEGIN
  IF LEN(@Field)<=0
  BEGIN
   RAISERROR('Field name cannot be empty. _
    StoreProcedure/MessageHelper',16,1)    
   RETURN @FAILED
  END
  SELECT @ValidationMessage = @Field + ' ' + @EMPTY_MESSAGE 
 END

 IF @ValidationConstraint = @LEN
 BEGIN
  IF @MinLenght IS NULL OR @MinLenght <=0
  BEGIN
   RAISERROR('Minimum length cannot be empty. _
    StoreProcedure/MessageHelper',16,1)    
   RETURN @FAILED
  END
  ELSE
  BEGIN
   SELECT @ValidationMessage = @Field + ' ' + _
   @MINIMUM_LENGHT_MESSAGE + ' ' + CONVERT(varchar, @MinLenght)
  END
 END

 IF @ValidationConstraint = @NO_DATA_EXIST 
 BEGIN    
  SELECT @ValidationMessage = @NO_DATA_EXIST_MESSAGE   
 END
END

Write your procedure for insert data into Customer table:

Hide   Shrink    Copy Code

CREATE PROCEDURE [dbo].[Customer_Set]
 --Input values
 @Name as varchar(50),
    @Address as varchar(250),    
 @Mobile as varchar(50),
 --Output values
 @LASTID bigint OUTPUT,
 @MESSAGE varchar(200) =NULL OUTPUT
AS
SET NOCOUNT ON
BEGIN
 --Constraint Variables For Readable Return Value  
 DECLARE @SUCCESSED int,
  @FAILED int   

 --Constraint Variables For Readable Validation Operation  
 DECLARE @EMPTY int,
  @LEN int  
 
 BEGIN TRY
  --Get constraint value for success and failed
  EXEC ReturnMessage @SUCCESSED output, @FAILED output  
  --Get constraint value for validation. @EMPTY is for empty check 
                   --and @LEN is for length check common messaging system.
  EXEC GetValidationConstraint @EMPTY output, @LEN output
 
  --Validation
  IF LEN(@Name)=0
  BEGIN   
   EXEC MessageHelper 'Name', @EMPTY,@MESSAGE OUTPUT 
                                    --It will generate a common empty message.
   RETURN @FAILED-- Readable Failed Return
  END

  IF LEN(@Name)<3
  BEGIN   
   EXEC MessageHelper 'Name',3, @LEN,@MESSAGE OUTPUT 
                                  --It will generate a common length check message.
   RETURN @FAILED-- Readable Failed Return
  END
  
  --Data insertion
  INSERT INTO [dbo].[Customer]
           ([Name]
           ,[Address]
           ,[Mobile])
  VALUES
           (@Name
           ,@Address
           ,@Mobile)
   
   SELECT @LASTID=SCOPE_IDENTITY()
 END TRY
 BEGIN CATCH -- Error Trapping Section
  DECLARE @ErrorMessage nvarchar(4000);
  DECLARE @ErrorSeverity int;
  DECLARE @ErrorState int;
  
  SELECT 
   @ErrorMessage = ERROR_MESSAGE(),
   @ErrorSeverity = ERROR_SEVERITY(),
   @ErrorState = ERROR_STATE();
  
  RAISERROR (@ErrorMessage,@ErrorSeverity,@ErrorState);
  RETURN @FAILED  -- Readable Failed Return
 END CATCH

 RETURN @SUCCESSED -- Readable Success Return
END

In the above way, all messages in a system will remain common. Now write stored procedure for getting all records from Customer table.

Hide   Shrink    Copy Code

CREATE PROCEDURE [dbo].[Customer_Get] 
 --Output values 
 @TOTAL_ROWS bigint OUTPUT, 
 @MESSAGE varchar(200) =NULL OUTPUT
 
AS
BEGIN
 SET NOCOUNT ON
 --Variables
 DECLARE @SUCCESSED int,
  @FAILED int  

 DECLARE @EMPTY int,
  @LEN int,
  @NO_DATA_EXIST int 
 
 BEGIN TRY
  --Get constraint value
  EXEC ReturnMessage @SUCCESSED OUTPUT, @FAILED OUTPUT  
  EXEC GetValidationConstraint @EMPTY OUTPUT, _
   @LEN OUTPUT,@NO_DATA_EXIST OUTPUT
 
  --Validation
  IF (SELECT COUNT(CustomerId) FROM  Customer )<= 0 
  BEGIN   
   EXEC MessageHelper '', @NO_DATA_EXIST,@MESSAGE OUTPUT 
    --It will generate common no data exist message.
   SELECT @TOTAL_ROWS=0
    
   RETURN @SUCCESSED
  END
  
  --Data retrieval 
  SELECT [CustomerId]
    ,[Name]
    ,[Address]
    ,[Mobile]   
  FROM [dbo].[Customer]  

  --Get total rows 
  SELECT @TOTAL_ROWS=@@ROWCOUNT
   
 END TRY
 BEGIN CATCH
  DECLARE @ErrorMessage nvarchar(4000);
  DECLARE @ErrorSeverity int;
  DECLARE @ErrorState int;
  
  SELECT 
   @ErrorMessage = ERROR_MESSAGE(),
   @ErrorSeverity = ERROR_SEVERITY(),
   @ErrorState = ERROR_STATE();  
  
  RAISERROR (@ErrorMessage,@ErrorSeverity,@ErrorState);
  RETURN @FAILED
 END CATCH

 RETURN @SUCCESSED
END

Write procedure for delete record from Customer table:

Hide   Shrink    Copy Code

CREATE  PROCEDURE [dbo].[Customer_DeleteById]
 --Input values
 @CustomerId bigint, 
 @MESSAGE varchar(200) =NULL OUTPUT
AS
BEGIN
 --Variables
 DECLARE @SUCCESSED int,
  @FAILED int   

 DECLARE @EMPTY int,
  @LEN int

 BEGIN TRY
  --Get constraint value
  EXEC ReturnMessage @SUCCESSED OUTPUT, @FAILED OUTPUT  
  EXEC GetValidationConstraint @EMPTY OUTPUT, @LEN OUTPUT
 
  --Validation
  IF @@CustomerId <=0
  BEGIN   
   EXEC MessageHelper 'Customer Id', @EMPTY,@MESSAGE OUTPUT
   RETURN @FAILED
  END
  
  --Data deletion 
  DELETE FROM [dbo].[Customer]
    WHERE (CustomerId = @CustomerId)

 END TRY
 BEGIN CATCH
  DECLARE @ErrorMessage nvarchar(4000);
  DECLARE @ErrorSeverity int;
  DECLARE @ErrorState int;
  
  SELECT 
   @ErrorMessage = ERROR_MESSAGE(),
   @ErrorSeverity = ERROR_SEVERITY(),
   @ErrorState = ERROR_STATE();
  
  RAISERROR (@ErrorMessage,@ErrorSeverity,@ErrorState);
  RETURN @FAILED
 END CATCH

 RETURN @SUCCESSED
END

So by some additional stored procedures, we can build a common messaging and validation system for web or software applications. By building a common system or framework, we can reduce maintenance time for our software project. And it is easy to understand the whole system.

CONCLUSION

This demonstration will help you to develop your SQL framework.

Thank You!