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sql server programming : case conditional
determine whether code certain logic in an stored procedure or a dll. SP is nice idea maybe cause I can modify it more easily than a dll. However, I would like to use 'case' instead of 'if ... then' Unfortunately, I would prefer to use 'case' rather than 'if ... then' and I have been unable to get a case conditional syntax to work. The 'if ... then' conditional in an SP for procedural programming in t-sql is simple as documented on this forum as elsewhere. My question to you is: " is it possible to use case select type logic outside of SQL statements for t-sql type procedural programming and if so, what is the proper syntax?" I leave discussion of the merits, unless you have a strong opinion to express, to other posts.
CASE ... END is an expression in T-SQL, and there is no CASE statement
to control program flow. You will have to find another way to express what you want to do using one of the control structures in the language, like IF .. ELSE, GOTO statements, recursion, WHILE, and so on. Steve Kass Drew University [quoted text, click to view] Unit Zapparov wrote:
>ok, i'm at an impase regarding t-sql procedural progamming. I'm trying to >determine whether code certain logic in an stored procedure or a dll. > >SP is nice idea maybe cause I can modify it more easily than a dll. > >However, I would like to use 'case' instead of 'if ... then' Unfortunately, >I would prefer to use 'case' rather than 'if ... then' and I have been >unable to get a case conditional syntax to work. The 'if ... then' >conditional in an SP for procedural programming in t-sql is simple as >documented on this forum as elsewhere. > >My question to you is: " is it possible to use case select type logic >outside of SQL statements for t-sql type procedural programming and if so, >what is the proper syntax?" > >I leave discussion of the merits, unless you have a strong opinion to >express, to other posts. > > >
You mean something like
SELECT CASE MyField1 WHEN < 20 THEN 0 ELSE MyField1 END As MyField1Output FROM SomeTable If you are manipulating large result sets, it is generally better to set up the filter, if possible, in T-SQL. If the sets are small, you will likely find similar perf in each, so pick the one you find easier to maintain. If the filtering logic is business rules related, you may want to pull it out into the business layer, regardless. In other words, if business rules affect how the filter is accomplished, not simply business requires it to be filtered in a certain manner. -- Gregory A. Beamer MVP; MCP: +I, SE, SD, DBA ************************************************ Think Outside the Box! ************************************************ [quoted text, click to view] "Unit Zapparov" <unit@discussions.microsoft.com> wrote in message news:uJECvz7bEHA.2352@TK2MSFTNGP09.phx.gbl... > ok, i'm at an impase regarding t-sql procedural progamming. I'm trying to > determine whether code certain logic in an stored procedure or a dll. > > SP is nice idea maybe cause I can modify it more easily than a dll. > > However, I would like to use 'case' instead of 'if ... then' Unfortunately, > I would prefer to use 'case' rather than 'if ... then' and I have been > unable to get a case conditional syntax to work. The 'if ... then' > conditional in an SP for procedural programming in t-sql is simple as > documented on this forum as elsewhere. > > My question to you is: " is it possible to use case select type logic > outside of SQL statements for t-sql type procedural programming and if so, > what is the proper syntax?" > > I leave discussion of the merits, unless you have a strong opinion to > express, to other posts. > >
Cowboy, I understand my use of the term 't-sql' was incorrect. I meant, as I
believe Steve in the previous post understood, to ask about the use of CASE .... WHEN ... ELSE ... END outside of any SQL statement in order to control the processing of a procedure. The use of IF ... THEN ... ELSE is well documented, as in: CREATE PROC report @switch varchar(20)IF @switch = 'something' BEGIN ' some code ENDELSE BEGIN ... ENDIF @switch = 'somethingelse' BEGIN' some code ENDELSE BEGIN ... END' and so on ...However, I could not find documentation of the use of CASE ... WHEN ... ELSE ... END in a similar manner to control SP execution. As Steve confirmed, MS Sql Server does not support such useage for CASE. I do understand that CASE is used frequently inside SQL statements. The above useage of IF ... THEN ... ELSE or as Steve mentioned, "IF .. ELSE, GOTO statements, recursion, WHILE, and so on", are applicable to control SP program flow. -------------------------------------- [quoted text, click to view] "Cowboy (Gregory A. Beamer) [MVP]" <NoSpamMgbworld@comcast.netNoSpamM> wrote in message news:eF89eJAcEHA.3664@TK2MSFTNGP12.phx.gbl... > You mean something like > > SELECT CASE MyField1 WHEN < 20 THEN 0 > ELSE MyField1 END As MyField1Output > FROM SomeTable > > If you are manipulating large result sets, it is generally better to set up > the filter, if possible, in T-SQL. If the sets are small, you will likely > find similar perf in each, so pick the one you find easier to maintain. If > the filtering logic is business rules related, you may want to pull it out > into the business layer, regardless. In other words, if business rules > affect how the filter is accomplished, not simply business requires it to be > filtered in a certain manner. > > -- > Gregory A. Beamer > MVP; MCP: +I, SE, SD, DBA > > ************************************************ > Think Outside the Box! > ************************************************ > "Unit Zapparov" <unit@discussions.microsoft.com> wrote in message > news:uJECvz7bEHA.2352@TK2MSFTNGP09.phx.gbl... > > ok, i'm at an impase regarding t-sql procedural progamming. I'm trying to > > determine whether code certain logic in an stored procedure or a dll. > > > > SP is nice idea maybe cause I can modify it more easily than a dll. > > > > However, I would like to use 'case' instead of 'if ... then' > Unfortunately, > > I would prefer to use 'case' rather than 'if ... then' and I have been > > unable to get a case conditional syntax to work. The 'if ... then' > > conditional in an SP for procedural programming in t-sql is simple as > > documented on this forum as elsewhere. > > > > My question to you is: " is it possible to use case select type logic > > outside of SQL statements for t-sql type procedural programming and if so, > > what is the proper syntax?" > > > > I leave discussion of the merits, unless you have a strong opinion to > > express, to other posts. > > > > > >
But, I'll try to use the CASE logic inside the SQL statement to see if it
meets my needs. Thanks [quoted text, click to view] "Cowboy (Gregory A. Beamer) [MVP]" <NoSpamMgbworld@comcast.netNoSpamM> wrote in message news:eF89eJAcEHA.3664@TK2MSFTNGP12.phx.gbl... > You mean something like > > SELECT CASE MyField1 WHEN < 20 THEN 0 > ELSE MyField1 END As MyField1Output > FROM SomeTable > > If you are manipulating large result sets, it is generally better to set up > the filter, if possible, in T-SQL. If the sets are small, you will likely > find similar perf in each, so pick the one you find easier to maintain. If > the filtering logic is business rules related, you may want to pull it out > into the business layer, regardless. In other words, if business rules > affect how the filter is accomplished, not simply business requires it to be > filtered in a certain manner. > > -- > Gregory A. Beamer > MVP; MCP: +I, SE, SD, DBA > > ************************************************ > Think Outside the Box! > ************************************************ > "Unit Zapparov" <unit@discussions.microsoft.com> wrote in message > news:uJECvz7bEHA.2352@TK2MSFTNGP09.phx.gbl... > > ok, i'm at an impase regarding t-sql procedural progamming. I'm trying to > > determine whether code certain logic in an stored procedure or a dll. > > > > SP is nice idea maybe cause I can modify it more easily than a dll. > > > > However, I would like to use 'case' instead of 'if ... then' > Unfortunately, > > I would prefer to use 'case' rather than 'if ... then' and I have been > > unable to get a case conditional syntax to work. The 'if ... then' > > conditional in an SP for procedural programming in t-sql is simple as > > documented on this forum as elsewhere. > > > > My question to you is: " is it possible to use case select type logic > > outside of SQL statements for t-sql type procedural programming and if so, > > what is the proper syntax?" > > > > I leave discussion of the merits, unless you have a strong opinion to > > express, to other posts. > > > > > >
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