Php/docs/mysqli.select-db
mysqli::select_db
mysqli_select_db
(PHP 5, PHP 7)
mysqli::select_db -- mysqli_select_db — 选择用于数据库查询的默认数据库
说明
面向对象风格
mysqli::select_db
( string $dbname
) : bool
过程化风格
mysqli_select_db
( mysqli $link
, string $dbname
) : bool
针对本次数据库连接用于数据库查询的默认数据库。
Note:
本函数应该只被用在改变本次链接的数据库，你也能在mysqli_connect()第四个参数确认默认数据库。
返回值
成功时返回 true， 或者在失败时返回 false。
范例
Example #1 mysqli::select_db() example
面向对象风格
<?php$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();?>
过程化风格
<?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);?>
以上例程会输出：
Default database is test. Default database is world.
