🎉 Added chainable fluent DB helper and unit test

[harunollyo]

Summary

Added a chainable, fluent DB for building and executing database queries with improved security and SQL injection prevention. The builder also provides better extensibility, maintainability, and debugging support through the to_sql() method

Key Benefits

• Improved security — centralizes query construction and parameter binding to help prevent SQL injection.
• Extensibility — provides a structured foundation for adding new query features without expanding a collection of independent helper methods.
• Better readability — uses a fluent, chainable API for clearer and more maintainable queries.
• Debugging support — provides a to_sql() method to inspect the generated SQL query.
• Consistent database handling — keeps query preparation and execution aligned with WordPress $wpdb.
• Easier maintenance — centralizes query-building logic in QueryBuilder.php.

Example Usage

$users = DB::table( 'users' )
    ->select( [ 'ID', 'user_login', 'user_email' ] )
    ->where( 'user_status', 0 )
    ->order_by( 'ID', 'DESC' )
    ->limit( 10 )
    ->get();

$course = DB::table( 'posts' )
    ->where( 'post_id', $course_id )
    ->first();

$count = DB::table( 'options' )
    ->where( 'option_id', $id )
    ->count();

For debugging, the generated SQL can be inspected without executing the query:

$sql = DB::table( 'comments' )
    ->where( 'comment_id', $id )
    ->to_sql();

The new builder provides a safer, more maintainable, extensible, and debuggable foundation for database queries while allowing existing query logic to be migrated incrementally.

Testing