(PHP 5, PHP 7, PHP 8)
mysqli::select_db -- mysqli_select_db — 選擇用于數據庫查詢(xún)的默認數據庫
面向對象風(fēng)格
$dbname): bool過(guò)程化風(fēng)格
針對本次數據庫連接用于數據庫查詢(xún)的默認數據庫。
注意:
本函數應該只被用在改變本次鏈接的數據庫，你也能在mysqli_connect()第四個(gè)參數確認默認數據庫。
成功時(shí)返回 true， 或者在失敗時(shí)返回 false。
示例 #1 mysqli::select_db() example
面向對象風(fēng)格
<?php
$mysqli = new mysqli("localhost", "my_user", "my_password", "test");
/* check connection */
if (mysqli_connect_errno()) {
printf("Connect failed: %s\n", mysqli_connect_error());
exit();
}
/* return name of current default database */
if ($result = $mysqli->query("SELECT DATABASE()")) {
$row = $result->fetch_row();
printf("Default database is %s.\n", $row[0]);
$result->close();
}
/* change db to world db */
$mysqli->select_db("world");
/* return name of current default database */
if ($result = $mysqli->query("SELECT DATABASE()")) {
$row = $result->fetch_row();
printf("Default database is %s.\n", $row[0]);
$result->close();
}
$mysqli->close();
?>
過(guò)程化風(fēng)格
<?php
$link = mysqli_connect("localhost", "my_user", "my_password", "test");
/* check connection */
if (mysqli_connect_errno()) {
printf("Connect failed: %s\n", mysqli_connect_error());
exit();
}
/* return name of current default database */
if ($result = mysqli_query($link, "SELECT DATABASE()")) {
$row = mysqli_fetch_row($result);
printf("Default database is %s.\n", $row[0]);
mysqli_free_result($result);
}
/* change db to world db */
mysqli_select_db($link, "world");
/* return name of current default database */
if ($result = mysqli_query($link, "SELECT DATABASE()")) {
$row = mysqli_fetch_row($result);
printf("Default database is %s.\n", $row[0]);
mysqli_free_result($result);
}
mysqli_close($link);
?>
以上例程會(huì )輸出：
Default database is test. Default database is world.