Fix WP 4.9: use run_query_via_mysqli() for drop/reset, keep wpdb for query/import

Co-authored-by: swissspidy <841956+swissspidy@users.noreply.github.com>

Author: Copilot

features/db.feature

@@ -405,7 +405,7 @@ Feature: Perform database operations
       """
     And STDERR should contain:
       """
-      Query via wpdb:
+      Query via mysqli:
       """
 
   @require-mysql-or-mariadb
@@ -430,7 +430,7 @@ Feature: Perform database operations
       """
     And STDERR should contain:
       """
-      Query via wpdb:
+      Query via mysqli:
       """
 
   # Skipped on Windows due to persistent file locking issues when run via Behat.

src/DB_Command.php

@@ -1959,6 +1959,56 @@ private static function get_create_query() {
 		return $create_query;
 	}
 
+	/**
+	 * Run a single DDL query (e.g. DROP/CREATE DATABASE) using PHP's mysqli extension.
+	 *
+	 * Used as a fallback when the mysql/mariadb CLI binary is not available.
+	 * Creates a fresh connection per call so that DDL operations like
+	 * DROP DATABASE followed by CREATE DATABASE work correctly.
+	 *
+	 * @param string $query SQL query to execute.
+	 */
+	protected function run_query_via_mysqli( $query ) {
+		$db_host = DB_HOST;
+		$port    = null;
+		$socket  = null;
+
+		if ( ':' === substr( $db_host, 0, 1 ) ) {
+			$socket  = substr( $db_host, 1 );
+			$db_host = 'localhost';
+		} else {
+			$parts   = explode( ':', $db_host, 2 );
+			$db_host = $parts[0];
+			if ( isset( $parts[1] ) ) {
+				$port_or_socket = trim( $parts[1] );
+				if ( '' !== $port_or_socket && '/' === $port_or_socket[0] ) {
+					$socket = $port_or_socket;
+				} elseif ( '' !== $port_or_socket ) {
+					$port = (int) $port_or_socket;
+				}
+			}
+		}
+
+		// When using a socket, pass 0 for port. When a port is explicitly set, use it; otherwise use the default.
+		$port_value   = null !== $port ? $port : 0;
+		$socket_value = null !== $socket ? $socket : '';
+
+		// No database is selected intentionally — DDL operations like DROP/CREATE DATABASE work at the server level.
+		// phpcs:ignore WordPress.DB.RestrictedClasses.mysql__mysqli -- direct mysqli required as wpdb fallback when mysql binary is unavailable.
+		$conn = new mysqli( $db_host, DB_USER, DB_PASSWORD, '', $port_value, $socket_value );
+
+		if ( $conn->connect_errno ) {
+			WP_CLI::error( sprintf( 'Failed to connect to the database: %s', $conn->connect_error ) );
+		}
+
+		if ( ! $conn->query( $query ) ) {
+			$error = $conn->error;
+			$conn->close();
+			WP_CLI::error( sprintf( 'Query failed: %s', $error ) );
+		}
+		$conn->close();
+	}
+
 	/**
 	 * Run a single query via the 'mysql' binary.
 	 *
@@ -1970,20 +2020,8 @@ private static function get_create_query() {
 	 */
 	protected function run_query( $query, $assoc_args = [] ) {
 		if ( ! $this->is_mysql_binary_available() ) {
-			WP_CLI::debug( "Query via wpdb: {$query}", 'db' );
-			$this->maybe_load_wpdb();
-			global $wpdb;
-
-			if ( ! isset( $wpdb ) ) {
-				WP_CLI::error( 'WordPress database (wpdb) could not be initialized. Please ensure WordPress core files are properly installed.' );
-			}
-
-			// phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared
-			$result = $wpdb->query( $query );
-			if ( false === $result ) {
-				// phpcs:ignore WordPress.WP.AlternativeFunctions.strip_tags_strip_tags
-				WP_CLI::error( 'Query failed: ' . strip_tags( $wpdb->last_error ) );
-			}
+			WP_CLI::debug( "Query via mysqli: {$query}", 'db' );
+			$this->run_query_via_mysqli( $query );
 			return;
 		}