Defensive Database Programming - Red Gate Software

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Chapter 7: Advanced Use of Constraints'Active') ;INSERT INTO dbo.Tickets( TicketID ,AssignedToDeveloperID ,Description ,TicketStatus ,DeveloperStatus)VALUES ( 1 ,1 ,'Cannot print TPS report' ,'Active' ,'Active') ;INSERT INTO dbo.Tickets( TicketID ,AssignedToDeveloperID ,Description ,TicketStatus ,DeveloperStatus)VALUES ( 2 ,1 ,'TPS report for June hangs' ,'Closed' ,NULL) ;Listing 7-16: Repopulating Developers and Tickets tables.If we rerun Listing 7-11, it will raise an error, confirming that Justin cannot go onvacation, because there is an active ticket assigned to him224
Chapter 7: Advanced Use of ConstraintsNow, when we close an open ticket, we also need to set DeveloperStatus to NULL, asshown in Listing 7-17.UPDATE dbo.TicketsSET TicketStatus = 'Closed' ,DeveloperStatus = NULLWHERE TicketID = 1 ;Listing 7-17: Closing the ticket.At this moment, both tickets assigned to Justin are closed, and DeveloperStatusis NULL for both those tickets. This means that, for these tickets, the pair of columns(AssignedDeveloperID, DeveloperStatus) does not refer to any row in theDevelopers table, because DeveloperStatus is NULL. Note that, even for closedtickets, we still need to ensure that Tickets.AssignedDeveloperID refers to a validDevelopers.DeveloperID; this is why we have another FOREIGN KEY constraint(FK_Tickets_Developers) on AssignedDeveloperID only.Let's proceed with the testing. If Justin goes on vacation, we expect that no rows in theTickets table should be modified, as verified by Listing 7-18.-- we need a transaction-- so that we can easily restore test dataBEGIN TRANSACTION ;GOSELECT TicketID ,AssignedToDeveloperID ,Description ,TicketStatus ,DeveloperStatusFROM dbo.Tickets ;GOUPDATE dbo.DevelopersSET DeveloperStatus = 'Vacation'WHERE DeveloperID = 1 ;GOSELECT TicketID ,225
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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 2: Code Vulnerabilitiesdue
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Chapter 4: When Upgrading Breaks Co
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Chapter 5: Reusing T-SQL CodeThe Da
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Chapter 5: Reusing T-SQL CodeBEGINS
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Chapter 5: Reusing T-SQL CodeWe als
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Chapter 5: Reusing T-SQL CodeLet's
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Chapter 5: Reusing T-SQL CodeStateC
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Chapter 5: Reusing T-SQL CodeBEGIN
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Chapter 5: Reusing T-SQL CodeSELECT
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Chapter 5: Reusing T-SQL CodeINSERT
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Chapter 5: Reusing T-SQL CodeUnique
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Chapter 8: Defensive Error Handling
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Defensive Database Programming - Red Gate Software

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