Better and also concise way to write a query..(Mysql + C language)

Is there a more concise way to write the following query (using Mysql + C ):

 memset(query, 0, 200);
            strcat(query, "UPDATE Sconti SET ");
            strcat(query, "Sconto = '");
            strcat(query, nuovo_sconto);
            strcat(query, "' WHERE For_Sconti ='");
            strcat(query, For_Sconti);
            strcat(query, "' AND Cat_Sconti='");
            strcat(query, Cat_Sconti);
            strcat(query, "';");

            if (mysql_query (conn, query)) {
                        printf("\nErrore query:\n");
                printf("%s", mysql_error(conn),"\n");

The problem is that if I have to update a table having 12 fields, things get annoying..

Tha开发者_开发问答nks, Vera

Depending on the version of MySQL you are using, you can use prepared statements. Check out chapter 20.9 of the MySQL Reference Manual.

With prepared statements you can setup a query like this:
char *queryText = "Update Sconti set Sconto = ? where for_sconti = ? and cat_sconti = ?";

char string[512];

//code to clean the string :)
sprintf(string,"UPDATE Sconti SET Sconto = '%f' WHERE For_Sconti ='%f' AND Cat_Sconti='%f';",scontoValue,forScontiValue,catScontiValue);

Search for sprintf in this page:

http://www.utas.edu.au/infosys/info/documentation/C/CStdLib.html

Yep, you can use sprintf and do something like ...

sprintf(query, "UPDATE Sconti Set "
   " Sconto = '%s'"
   "WHERE FOR_Sconti = '%s'|
   /* etc .... */
   ";", nuove_sconto, For_Sconti, Cat_Sconti);

Note I use a C trick that in C "a""b" is equivalent to "ab" and so equivalet to

"a"
"b"

always sprintf

it's a glorous function that act as a printf but write over a string istead of writing over the standard output. It's very simple to use by everybody since there is no c developer which does not know printf since his first hello world! Adapring it to your code would look like:

char yourString[512];
sprintf(yourString,"UPDATE Sconti SET Sconto = '%f' WHERE For_Sconti ='%f' AND Cat_Sconti='%f';",nuovo_sconto,For_Sconti,Cat_Sconti);

Cheers,