mysql - How to insert record which has foregin key referenced to primary key of another table in PHP Script? -

here code-

<?php     session_start();     $con = mysqli_connect("localhost", "root", "", "placement")      or die("failed connect mysql: " . mysqli_error()); // connecting mysql database      // variable declaration     $statename = mysqli_real_escape_string($con, $_post["txtstatename"]);     $description = mysqli_real_escape_string($con, $_post["txtdescription"]);     $countryname = mysqli_real_escape_string($con, $_post["selectcountryname"]);     $countryid = "select countryid tbl_country_master countryname='$countryname'";      // insert query     $sql = "insert tbl_state_master(statename, description, countryid) values ('$statename', '$description', '$countryid')";      if(!mysqli_query($con, $sql))     {         die('error: ' . mysqli_error($con));     }     else     {         header("location: frmaddstate.php?msg=1");     }      mysqli_close($con);?> 

countryid in tbl_state_master foreign key , referenced primary key of tbl_country_master. i'm not able insert data i'm getting error.

you never executed query that's supposed return country id. set $countryid sql string. should be:

$sql = "select countryid tbl_country_master countryname='$countryname'"; $result = mysqli_query($con, $sql); $row = mysqli_fetch_assoc($result); if ($row) {     $countryid = $row['countryid']; } 

but ou don't need 2 separate queries, in one:

$sql = "insert tbl_state_master(statename, description, countryid)         select '$statename', '$description', countryid         tbl_country_master countryname='$countryname'";