John Davidson

Message:

hello i am trying to do a select query from multiple tables and I made variables for the tables names and it works if I removed the variables and put the tables names instead what to do?

$table_name = $wpdb->prefix . 'student_list';

 $table_name1 = $wpdb->prefix . 'courses';

 $table_name2 = $wpdb->prefix . 'registration';  







$registrations = $wpdb->get_results("SELECT registration_id , $table_name1.course_id ,$table_name.student_id ,$table_name1.name, $table_name1.course_name ,$table_name1.course_code FROM $table_name ,$table_name1, $table_name2 WHERE $table_name2.course_id = $table_name1.course_id and $table_name2.student_id = $table_name.student_id");

---

My Answer:
> If you are using PHP and MySQL, you can dynamically build your SQL query using variables for table names. Here is an example of how you can achieve this:

php
$table_name1 = "table1";
$table_name2 = "table2";

$sql = "SELECT * FROM $table_name1, $table_name2 WHERE $table_name1.id = $table_name2.id";

$result = mysqli_query($connection, $sql);

if (mysqli_num_rows($result) > 0) {
while ($row = mysqli_fetch_assoc($result)) {
// Process the data
}
} else {
echo "No results found";
}


In this example, we are using variables `$table_name1` and `$table_name2` to store the table names. Then, we are dynamically building the SQL query using these variables. Make sure to properly sanitize and validate the table names to prevent SQL injection attacks.