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PHP

Send a MySQL query


mysql_query

(PHP 4, PHP 5)

mysql_querySend a MySQL query

Description

resource mysql_query ( string $query [, resource $link_identifier = NULL ] )

mysql_query() sends a unique query (multiple queries are not supported) to the currently active database on the server that's associated with the specified link_identifier.

Parameters

query

An SQL query

The query string should not end with a semicolon. Data inside the query should be properly escaped.

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 no connection is found or established, an E_WARNING level error is generated.

Return Values

For SELECT, SHOW, DESCRIBE, EXPLAIN and other statements returning resultset, mysql_query() returns a resource on success, or FALSE on error.

For other type of SQL statements, INSERT, 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.

Examples

Example #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());
}

?>

Example #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 an 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);
?>

See Also



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Android Reference

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