Question

是否有更简明的方式来撰写以下询问(使用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("
Errore query:
");
                printf("%s", mysql_error(conn),"
");

问题是,如果我需要更新一个有12个领域的表格,事情就会消失。

谢意

Answer 1

根据你使用的MySQL版本,你可以使用发言稿。 http://dev.mysql.com/doc/refman/5.1/en/c.html 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 = ?";

Answer 2

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);

在该页搜索印本:

rel=“nofollow”http://www.utas.edu.au/infosys/info/documentation/C/CStdLib.html

Answer 3

页: 1 ......

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

说明一使用“C”模板,在Ca"”b 中, b 等于ab>, 等同

"a"
"b"

Answer 4

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,

友情链接