在Wordpress中激活插件后未创建数据库表

Question

I am trying to create a database table within a my wordpress plugin main file. Here is my code to create the database table. When I activate the plugin from Wordpress control panel, plugin activate but database tables doesn't create.

     <?php   
     function keywords_ranker_install() {
 global $wpdb;
 global $keyword_rankerdb;
 $keyword_rankerdb = "1.0";
 $table_name = $wpdb->prefix . "search_engine";

        if($wpdb->get_var("SHOW TABLES LIKE '$table_name'")!= $table_name) {

        $sql = "CREATE TABLE IF NOT EXISTS ".$table_name." (
        id int(11) NOT NULL AUTO_INCREMENT,
        engine text NOT NULL,
        PRIMARY KEY ('id'));";

    //reference to upgrade.php file
    require_once( ABSPATH . 'wp-admin/includes/upgrade.php' );
    dbDelta($sql);
    //$wpdb->query($sql);

    //update_option('keyword_ranker_version',$keyword_rankerdb);
    }
  //action hook for plugin activation 

   }//end of plugin installation
      register_activation_hook(__FILE__,'keywords_ranker_install' );

?>

I'm not sure what I'm missing, and any help would be much appreciated!

Answer 1

Your syntax is wrong and this IF NOT EXISTS is not needed because your condition is already checking that.

NOTE: I switched it to all single quotes so its easier to follow and removed the single quotes in (id);

function keywords_ranker_install() {
global $wpdb;
global $keyword_rankerdb;
$keyword_rankerdb = "1.0";
$table_name       = $wpdb->prefix . "search_engine";

if ( $wpdb->get_var( "SHOW TABLES LIKE '$table_name'" ) != $table_name ) {

    $sql = 'CREATE TABLE ' . $table_name . ' (
    id int(11) NOT NULL AUTO_INCREMENT,
    engine text NOT NULL,
    PRIMARY KEY (id))';

    //reference to upgrade.php file
    require_once( ABSPATH . 'wp-admin/includes/upgrade.php' );
    dbDelta( $sql );

    //update_option('keyword_ranker_version',$keyword_rankerdb);
}
//action hook for plugin activation

}

//end of plugin installation
register_activation_hook( __FILE__, 'keywords_ranker_install' );