oracle - Using PHP and oci8 to handle a query -

this past paper question database class i'm stuck with. i'm preparing exam, it's okay give away answer.

consider following schema:

borrow(userid: string, callnum: string, copynum: integer, checkout: date, return: date) 

here php function has error.

function countcheckedoutbookcopies($callnum){    $sql = "select count(*) bookcount borrow          return = null , callnum = '".$callnum."'";    $stid = oci_parse($this->conn, $sql); //assume $this->con correct    if($row = oci_fetch_object($stid)){      return $row->bookcount;    } else{      return -1;    }  } 

there 3 questions.

1.find error , fix it.

2.another error occurs, fix it.

3.despite being fixed, function return -1 time. why this?

i'm familiar procedural php using mysql. tried running code , resulted $stid returning boolean time because don't know part right , part wrong.

here things i've tried

1.changing '".$callnum."' '$callnum' (because how i've done in mysql)

2.changing return = null return = 'null' (but don't think case)

3.maybe there wrong concept of getting count(*) instead of *

edit: thought: feel oci8 , mysql pretty same thing, there reason prefer 1 on another? i'm sure mysql more popular one, school seems prefer using oci8 exam questions

thanks in advance!

despite "find error" , "another error occurs":

1.) "return null",

2.) this->conn supposed this->con,

3.) code missing oci_execute($stid);,

4.) oci_free_statement($stid);.

function countcheckedoutbookcopies($callnum){   $sql = "select count(*) bookcount borrow         return null , callnum = '$callnum'";   $stid = oci_parse($this->con, $sql); //assume $this->con correct   oci_execute($stid);    $ret = -1;   if($row = oci_fetch_object($stid)){     $ret = $row->bookcount;   }   oci_free_statement($stid);   return $ret;  }