Ticket #49654: 49654.patch

wp-admin/includes/upgrade.php

@@ -2361 +2361 @@
 }
 
 /**
+ * Drops a table in the database if it does exist.
+ *
+ * This method checks for an existing table and drops it if it exist.
+ * It doesn't rely on MySQL's "IF NOT EXISTS" statement, but chooses
+ * to query all tables first and then run the SQL statement deleting the table.
+ *
+ * @since 5.5.0
+ *
+ * @global wpdb $wpdb WordPress database abstraction object.
+ *
+ * @param string $table_name Database table name to drop.
+ * @return bool If table already doesn't exist or was droped by function.
+ */
+function maybe_drop_table( $table_name ) {
+        global $wpdb;
+
+        $query = $wpdb->prepare( 'SHOW TABLES LIKE %s', $wpdb->esc_like( $table_name ) );
+
+        if !( $wpdb->get_var( $query ) == $table_name ) {
+                return true;
+        }
+
+        // Did find it, so try to drop it.
+        $wpdb->query( 'DROP TABLE ' . $table_name );
+
+        // We cannot directly tell that whether this succeeded!
+        if !( $wpdb->get_var( $query ) == $table_name ) {
+                return true;
+        }
+        return false;
+}
+
+/**
  * Drops a specified index from a table.
  *
  * @since 1.0.1