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SQL and loops

Scheduled Pinned Locked Moved C#
databasehelp
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  • M mhmo

    it will enhance the performance if I used the * format? //The answers are mulipchoice

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    Christian Graus
    wrote on last edited by
    #8

    By a factor of 210. Instead of 210 calls to the database, you make one, and then get all the values back into a local object that you can step through to find the replies. If the questions are multiple choice, and there are always 210 questions, then there are reasons to put an answer per column, in terms of being able to query the data. I'd just name them Answer1, Answer2 or something, so I didn't need to use [] all the time. Actually, even then I think I'd be more inclined to do a table that contains the student ID, the question ID and the answer in three columns, which would allow me to have as many or as few questions as I liked, still search the database for answers, and not waste any space. Christian Graus - Microsoft MVP - C++

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    • C Christian Graus

      By a factor of 210. Instead of 210 calls to the database, you make one, and then get all the values back into a local object that you can step through to find the replies. If the questions are multiple choice, and there are always 210 questions, then there are reasons to put an answer per column, in terms of being able to query the data. I'd just name them Answer1, Answer2 or something, so I didn't need to use [] all the time. Actually, even then I think I'd be more inclined to do a table that contains the student ID, the question ID and the answer in three columns, which would allow me to have as many or as few questions as I liked, still search the database for answers, and not waste any space. Christian Graus - Microsoft MVP - C++

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      mhmo
      wrote on last edited by
      #9

      The idea is that we will use Crystal Reports to print the answers of each or a specific student in a specific format. But why we should use []?!!

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      • M mhmo

        The idea is that we will use Crystal Reports to print the answers of each or a specific student in a specific format. But why we should use []?!!

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        Christian Graus
        wrote on last edited by
        #10

        mhmo wrote: The idea is that we will use Crystal Reports to print the answers of each or a specific student in a specific format. OK - either way, I think the data format I've specified is better, but I'm not familiar with Crystal Reports. If it needs all the values to be in one row, that would just be crap though. mhmo wrote: But why we should use []?!! Because a number on it's own is a reserved value, it's not really an acceptable column name. The [] tells it we used bad column names, and asks it to live with it. Christian Graus - Microsoft MVP - C++

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        • M mhmo

          Hi I have a table (named information) that contains columns with the names (1,2,3,4,5,6,7,8,...210) I entered a loop from i=1 to i=210 and inside the loop I write the following SQL statement: string an = "SELECT " + i.ToString() + " FROM information WHERE id = '" + s.Id + "';"; I should get the string contained in the column named i but what I get is i itself:(:( Whay would be the problem

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          J4amieC
          wrote on last edited by
          #11

          Just a hint: Read up on how others have structured a multi-choice test in a database. Your table schema is plain crazy!

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          • C Christian Graus

            mhmo wrote: The idea is that we will use Crystal Reports to print the answers of each or a specific student in a specific format. OK - either way, I think the data format I've specified is better, but I'm not familiar with Crystal Reports. If it needs all the values to be in one row, that would just be crap though. mhmo wrote: But why we should use []?!! Because a number on it's own is a reserved value, it's not really an acceptable column name. The [] tells it we used bad column names, and asks it to live with it. Christian Graus - Microsoft MVP - C++

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            mhmo
            wrote on last edited by
            #12

            thanks

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            • J J4amieC

              Just a hint: Read up on how others have structured a multi-choice test in a database. Your table schema is plain crazy!

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              mhmo
              wrote on last edited by
              #13

              Ok Would u give a link for some thanks

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              • M mhmo

                Ok Would u give a link for some thanks

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                J4amieC
                wrote on last edited by
                #14

                Google is your friend![^] ;)

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                • C Christian Graus

                  mhmo wrote: The idea is that we will use Crystal Reports to print the answers of each or a specific student in a specific format. OK - either way, I think the data format I've specified is better, but I'm not familiar with Crystal Reports. If it needs all the values to be in one row, that would just be crap though. mhmo wrote: But why we should use []?!! Because a number on it's own is a reserved value, it's not really an acceptable column name. The [] tells it we used bad column names, and asks it to live with it. Christian Graus - Microsoft MVP - C++

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                  MicrosoftBob
                  wrote on last edited by
                  #15

                  >... but I'm not familiar with Crystal Reports. If it needs all the values to be in one row, that would just be crap though. You can pivot data in Crystal, but it's still crap.

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                  • M mhmo

                    Ok Would u give a link for some thanks

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                    Matt Gerrans
                    wrote on last edited by
                    #16

                    Did you manually type in every column name? :doh: What is the deal with schools these days? Do they just tell you to use a database for something, without teaching you anything at all about how to use a database, or how to design your tables, etc.? Matt Gerrans

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                    • M Matt Gerrans

                      Did you manually type in every column name? :doh: What is the deal with schools these days? Do they just tell you to use a database for something, without teaching you anything at all about how to use a database, or how to design your tables, etc.? Matt Gerrans

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                      mhmo
                      wrote on last edited by
                      #17

                      No :laugh: I added them by a loop. Regarding teaching ... this is our way to learn do projects and projects projects projects projects projects projects . :omg::omg::omg:

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