Defensive Database Programming - Red Gate Software

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Chapter 7: Advanced Use of ConstraintsMsg 547, Level 16, State 0, Line 1The INSERT statement conflicted with the FOREIGN KEY SAMETABLE constraint "FK_InventoryLog_Self". The conflictoccurred in database "test2", table "dbo.InventoryLog".The statement has been terminated.Listing 7-29: A row with incorrect current quantity does not save.Also, we cannot withdraw more of an item than is currently in stock.INSERT INTO dbo.InventoryLog( ItemID ,ChangeDate ,ChangeQuantity ,CurrentQuantity ,PreviousChangeDate ,PreviousQuantity)VALUES ( 2 ,'20100102' ,-6 ,-1 , -- CurrentQuantity cannot be negative'20100101' ,5);Msg 547, Level 16, State 0, Line 1The INSERT statement conflicted with the CHECK constraint"CHK_InventoryLog_NonnegativeCurrentQuantity". The conflictoccurred in database "test2", table "dbo.InventoryLog",column 'CurrentQuantity'.The statement has been terminated.Listing 7-30: We cannot withdraw more than the available amount.However, we can take out a valid quantity of stock.240
Chapter 7: Advanced Use of ConstraintsINSERT INTO dbo.InventoryLog( ItemID ,ChangeDate ,ChangeQuantity ,CurrentQuantity ,PreviousChangeDate ,PreviousQuantity)VALUES ( 2 ,'20100102' ,-1 ,4 ,'20100101' ,5);Listing 7-31: Taking out a valid amount succeeds.So far our system has worked as expected. However, it still has loopholes. The commandshown in Listing 7-32 succeeds in withdrawing more stock of a given item than is available,by failing to provide a value for PreviousChangeDate.BEGIN TRANSACTION ;INSERT INTO dbo.InventoryLog( ItemID ,ChangeDate ,ChangeQuantity ,CurrentQuantity ,PreviousChangeDate ,PreviousQuantity)VALUES ( 2 ,'20100103' ,-20 ,0 ,NULL ,241
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Chapter 2: Code Vulnerabilities due
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Enforcing Data Integrity in the App
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About the AuthorAlex Kuznetsov has
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IntroductionResilient T-SQL code is
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IntroductionCh. 02: Code Vulnerabil
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IntroductionSpecific examples demon
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IntroductionWhat this book does not
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Chapter 1: Basic Defensive Database
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Chapter 5: Reusing T-SQL CodeBEGINS
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Defensive Database Programming - Red Gate Software

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