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[ Team LiB ] Recipe 6.7 Enforcing Business Rules with Column Expressions Problem You need to enforce a business rule based on multiple columns in a table at the user interface tier. Solution Use expression-based columns to enforce business rules at the user interface tier. | Team LiB Recipe 6.7 Enforcing Business Rules with Column Expressions Problem You need to enforce a business rule based on multiple columns in a table at the user interface tier. Solution Use expression-based columns to enforce business rules at the user interface tier. The business rule for this solution is that the sum of Fieldl and Field2 for a row in the table must be 10. The schema of table TBL0607 used in this solution is shown in Table 6-5. Table 6-5. TBL0607 schema Column name Data type Length Allow nulls Id int 4 No Fieldl nvarchar 4 No Field2 nvarchar 4 No The sample uses four stored procedures which are shown in Example 6-21 through Example 6-24 SP0607_Delete Used to delete a record from the table TBL0607 for a specified Id SP0607_Get Used to retrieve a record for a specified Id or all records from the table TBL0607 SP0607_Insert Used to insert a record into the table TBL0607 SP0607_Update Used to update a record in the table TBL0607 Example 6-21. Stored procedure SP0607_Delete CREATE PROCEDURE SP0607_Delete @Id int AS SET NOCOUNT ON delete from TBL0607 where Id @Id return 0 Example 6-22. Stored procedure SP0607_Get CREATE PROCEDURE SP0607_Get @Id int null AS SET NOCOUNT ON if @Id is not null begin select Id Field1 Field2 from TBL0607 where Id @Id return 0 end select Id Field1 Field2 from TBL0607 return 0 Example 6-23. Stored procedure SP0607_Insert CREATE PROCEDURE SP0607_Insert @Id int @Field1 int @Field2 int AS SET NOCOUNT ON insert TBL0607 Id Fieldl Field2 values @Id @Field1 @Field2 if @@rowcount 0 return 1 return 0 Example 6-24. Stored procedure SP0607_Update CREATE PROCEDURE SP0607_Update @Id int @Field1 int @Field2 int AS SET NOCOUNT ON update TBL0607 set Field1 @Field1 Field2 @Field2 .
