#1 Displaying the Oracle error message after a connection error
<?php
$conn = oci_connect("hr", "welcome", "localhost/XE");
if (!$conn) {
    $e = oci_error();   // For oci_connect errors do not pass a handle
    trigger_error(htmlentities($e['message']), E_USER_ERROR);
}
?>

#2 Displaying the Oracle error message after a parsing error
<?php
$stid = oci_parse($conn, "select ' from dual");  // note mismatched quote
if (!$stid) {
    $e = oci_error($conn);  // For oci_parse errors pass the connection handle
    trigger_error(htmlentities($e['message']), E_USER_ERROR);
}
?>

#3 Displaying the Oracle error message, the problematic statement,
     and the position of the problem of an execution error
<?php
$stid = oci_parse($conn, "select does_not_exist from dual");
$r = oci_execute($stid);
if (!$r) {
    $e = oci_error($stid);  // For oci_execute errors pass the statement handle
    print htmlentities($e['message']);
    print "\n<pre>\n";
    print htmlentities($e['sqltext']);
    printf("\n%".($e['offset']+1)."s", "^");
    print  "\n</pre>\n";
}
?>

Code

Result

PHP code example: oci_error

Returns the last error found. See documentation.

You can try this function yourself. Just edit the code and on "Run" to see the result.