mysqli::select_db

定義和用法

select_db() / mysqli_select_db()函數用於更改連接的默認數據庫。

實例

例子1 - 面向對像風格

更改連接的默認數據庫：

 <?php
$mysqli = new mysqli ( "localhost" , "my_user" , "my_password" , "my_db" ) ;

if ( $mysqli -> connect_errno ) {
  echo "Failed to connect to MySQL: " . $mysqli -> connect_error ;
  exit ( ) ;
}

// 返回當前默認數據庫的名稱
if ( $result = $mysqli -> query ( "SELECT DATABASE()" ) ) {
  $row = $result -> fetch_row ( ) ;
  echo "Default database is " . $row [ 0 ] ;
  $result -> close ( ) ;
}

// 將數據庫更改為"test" 數據庫
$mysqli -> select_db ( "test" ) ;

// 返回當前默認數據庫的名稱
if ( $result = $mysqli -> query ( "SELECT DATABASE()" ) ) {
  $row = $result -> fetch_row ( ) ;
  echo "Default database is " . $row [ 0 ] ;
  $result -> close ( ) ;
}

$mysqli -> close ( ) ;
?>

例子2 - 過程式風格

更改連接的默認數據庫：

 <?php
$con = mysqli_connect ( "localhost" , "my_user" , "my_password" , "my_db" ) ;

if ( mysqli_connect_errno ( ) ) {
  echo "Failed to connect to MySQL: " . mysqli_connect_error ( ) ;
  exit ;
}

// 返回當前默認數據庫的名稱
if ( $result = mysqli_query ( $con , "SELECT DATABASE()" ) ) {
  $row = mysqli_fetch_row ( $result ) ;
  echo "Default database is " . $row [ 0 ] ;
  mysqli_free_result ( $result ) ;
}

// 將數據庫更改為"test" 數據庫
mysqli_select_db ( $con , "test" ) ;

// 返回當前默認數據庫的名稱
if ( $result = mysqli_query ( $con , "SELECT DATABASE()" ) ) {
  $row = mysqli_fetch_row ( $result ) ;
  echo "Default database is " . $row [ 0 ] ;
  mysqli_free_result ( $result ) ;
}

// 關閉連接
mysqli_close ( $con ) ;
?>