oracle - Why does the sequence of parameters matter in SQL -

i think entry-level, haven't googled answer out..

when building queries, have use :1, :2... stuff in absolute sequence? tests, seems yes. doesn't calling stmt->setxxx(n, val) set nth parameter in statement val? how implemented?

please see example below:

    if (bnewcontent)    //new     {         sql = "begin packproductmanagement.procaddottcontent(:1, :2, :3, :4, :5, :6, :7); end; ";     }     else                //update     {         sql = "update ott_content set contentid = :1, contenttype = :2, fingerprint = :3, ishighlevelsafe = :4, ";         sql += "outprotection = :5, offlineplayback = :6, modifytime = sysdate ";         sql += "where contentid = :1";     }     try     {         openstatement(sql);         stmt->setstring(1, ac->contentdesc.contentid);         stmt->setuint(2, ac->contentdesc.contenttype);         stmt->setuint(3, ac->contentdesc.fingerprint);         stmt->setuint(4, ac->contentdesc.highlevelsafe);         stmt->setuint(5, ac->contentdesc.outputprotection);         stmt->setuint(6, ac->contentdesc.offlineplayback);         if (bnewcontent)         {             stmt->setuint(7, 0);        //only used if new         }         stmt->execute();          closestatement(true);     } 

in example, bnewcontent false, we're running update statement. above query works ok. if change update query below (removed contentid = :1, @ beginning of update statement), i'll ora-01722 invalid_number. why can't :2:3:4:5:6:1? if setxxx implemented queue, why above :1:2:3:4:5:6:1 work??

sql = "update ott_content set  contenttype = :2, fingerprint = :3, ishighlevelsafe = :4, "; sql += "outprotection = :5, offlineplayback = :6, modifytime = sysdate "; sql += "where contentid = :1"; 

thanks in advance!

edited:

test results below: (based on zza's answer)

sql = "update ott_content set contentid = :x contenttype = :x, fingerprint = :x, ishighlevelsafe = :x, "; sql += "outprotection = :x, offlineplayback = :x, modifytime = sysdate "; sql += "where contentid = :x"; 

above code doesn't work 6 parameters.

sql = "update ott_content set contentid = :1 contenttype = :x, fingerprint = :x, ishighlevelsafe = :x, "; sql += "outprotection = :x, offlineplayback = :x, modifytime = sysdate "; sql += "where contentid = :1"; 

above code works 6 parameters.

according oracle documentation bind variables used in order placed, not how named. that's why exception. so, need set parameters in order mentioned (the first mentioned contenttype in case remove first), , doesn't matter how they're named.

your code , still work:

if (bnewcontent)    //new {     sql = "begin packproductmanagement.procaddottcontent(:x, :x, :x, :x, :x, :x, :x); end; "; } else                //update {     sql = "update ott_content set contentid = :x, contenttype = :x, fingerprint = :x, ishighlevelsafe = :x, ";     sql += "outprotection = :x, offlineplayback = :x, modifytime = sysdate ";     sql += "where contentid = :x"; } try {     openstatement(sql);     stmt->setstring(1, ac->contentdesc.contentid);     stmt->setuint(2, ac->contentdesc.contenttype);     stmt->setuint(3, ac->contentdesc.fingerprint);     stmt->setuint(4, ac->contentdesc.highlevelsafe);     stmt->setuint(5, ac->contentdesc.outputprotection);     stmt->setuint(6, ac->contentdesc.offlineplayback);     if (bnewcontent)     {         stmt->setuint(7, 0);        //only used if new     }     stmt->execute();      closestatement(true); }