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).
Parameters
- query
A SQL query
The query string should not end with a semicolon.
-
link_identifier
The MySQL connection. If the
link identifier is not specified, the last link opened by
mysql_connect() is assumed. If no such link is found, it
will try to create one as if mysql_connect() was called
with no arguments. If by chance no connection is found or established, an
E_WARNING level warning is generated.
Return Values
For SELECT, SHOW, DESCRIBE or EXPLAIN statements,
mysql_query()
returns a resource on success, or FALSE on
error.
For other type of SQL statements, UPDATE, DELETE, DROP, etc,
mysql_query() returns TRUE on success
or FALSE on error.
The returned result resource should be passed to
mysql_fetch_array(), and other
functions for dealing with result tables, to access the returned data.
Use 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.
mysql_query() will also fail and return FALSE
if the user does not have permission to access the table(s) referenced by
the query.
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範例 1. Invalid Query
The following query is syntactically invalid, so
mysql_query() fails and returns FALSE.
<?php $result = mysql_query('SELECT * WHERE 1=1'); if (!$result) { die('Invalid query: ' . mysql_error()); }
?>
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範例 2. Valid Query
The following query is valid, so mysql_query()
returns a resource.
<?php // This could be supplied by a user, for example $firstname = 'fred'; $lastname = 'fox';
// Formulate Query // This is the best way to perform a SQL query // For more examples, see mysql_real_escape_string() $query = sprintf("SELECT firstname, lastname, address, age FROM friends WHERE firstname='%s' AND lastname='%s'", mysql_real_escape_string($firstname), mysql_real_escape_string($lastname));
// Perform Query $result = mysql_query($query);
// Check result // This shows the actual query sent to MySQL, and the error. Useful for debugging. if (!$result) { $message = 'Invalid query: ' . mysql_error() . "\n"; $message .= 'Whole query: ' . $query; die($message); }
// Use result // Attempting to print $result won't allow access to information in the resource // One of the mysql result functions must be used // See also mysql_result(), mysql_fetch_array(), mysql_fetch_row(), etc. while ($row = mysql_fetch_assoc($result)) { echo $row['firstname']; echo $row['lastname']; echo $row['address']; echo $row['age']; }
// Free the resources associated with the result set // This is done automatically at the end of the script mysql_free_result($result); ?>
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