PHP 手冊
上一頁 |  | 下一頁

# mysql_query

(PHP 3, PHP 4 , PHP 5)

mysql_query -- Send a MySQL query

## Description

resource mysql_query ( string query [, resource link_identifier])

mysql_query() sends a query to the currently active database on the server that's associated with the specified link identifier. If link_identifier isn't specified, the last opened link is assumed. If no link is open, the function tries to establish a link as if mysql_connect() was called with no arguments, and use it. The result of the query is buffered.

> 備注: The query string should not end with a semicolon.

Only for SELECT,SHOW,EXPLAIN or DESCRIBE statements mysql_query() returns a resource identifier or `FALSE` if the query was not executed correctly. For other type of SQL statements, mysql_query() returns `TRUE` on success and `FALSE` on error. A non-`FALSE` return value means that the query was legal and could be executed by the server. It does not indicate anything about the number of rows affected or returned. It is perfectly possible for a query to succeed but affect no rows or return no rows.

The following query is syntactically invalid, so mysql_query() fails and returns `FALSE`:

示範 1.mysql_query() example

`<?php $result = mysql_query('SELECT * WHERE 1=1'); if (!$result) { die('Invalid query: ' . mysql_error()); } ?>`

The following query is semantically invalid if my_col is not a column in the table my_tbl, so mysql_query() fails and returns `FALSE`:

示範 2.mysql_query()

`<?php $result = mysql_query('SELECT my_col FROM my_tbl'); if (!$result) { die('Invalid query: ' . mysql_error()); } ?>`

mysql_query() will also fail and return `FALSE` if you don't have permission to access the table(s) referenced by the query.

Assuming the query succeeds, you can call mysql_num_rows() to find out how many rows were returned for a SELECT statement or mysql_affected_rows() to find out how many rows were affected by a DELETE, INSERT, REPLACE, or UPDATE statement.

Only for SELECT,SHOW,DESCRIBE or EXPLAIN statements, mysql_query() returns a new result identifier that you can pass to mysql_fetch_array() and other functions dealing with result tables. When you are done with the result set, you can free the resources associated with it by calling mysql_free_result(). Although, the memory will automatically be freed at the end of the script's execution.

See also mysql_num_rows(), mysql_affected_rows(), mysql_unbuffered_query(), mysql_free_result(), mysql_fetch_array(), mysql_fetch_row(), mysql_fetch_assoc(), mysql_result(), mysql_select_db() and mysql_connect().

上一頁 | 最開頭 | 下一頁
mysql_ping | 上一層 | mysql_real_escape_string