PHP和mysqli：使用预准备语句选择多个条件

Question

I'm working on some prepared statements using mysqli in a php file with a database running on InnoDB. Most of the statements are working pretty well, but I have a select statement with multiple conditions that keeps returning a syntax error in my select statement, to be specific: near ? AND section_num = ? AND dept = ? AND semester = ? AND year = ? at line 1 as well as the following error:

Call to a member function bind_param() on a non-object.

Here's the snippet of code:

if (!$rs = $mysqli->query("SELECT id FROM courses WHERE course_num = ? AND section_num = ? AND dept = ? AND semester = ? AND year = ?")) {
        echo "Select Query Failed!: (" . $mysqli->errno . ") ". $mysqli->error;
    }
    if(!$rs->bind_param("ssssi", mysqli_real_escape_string($mysqli,$course_num), mysqli_real_escape_string($mysqli,$section_num),
        mysqli_real_escape_string($mysqli,$dept), mysqli_real_escape_string($mysqli,$semester), mysqli_real_escape_string($mysqli,$year))) {
        echo "Select Binding parameters failed: (" . $rs->errno .") " . $rs->error;
    }
    if (!$rs->execute()) {
        echo "Execute select failed: (" . $rs->errno . ") " . $rs->error;
    }

Any suggestions for how to form this statement to retrieve an id based on the 4 inputs would be great. Thanks!

Answer 1

You should be using prepare to prepare a statement, not query as that just executes a query.