PHP: Hypertext Preprocessor (original) (raw)

mysql_query

(PHP 4, PHP 5)

mysql_query — Send a MySQL query

Description

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 bymysql_connect() is assumed. If no such link is found, it will try to create one as if mysql_connect() had been called with no arguments. If no connection is found or established, an**[E_WARNING](errorfunc.constants.php#constant.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](reserved.constants.php#constant.false) on error.

For other type of SQL statements, INSERT, UPDATE, DELETE, DROP, etc,mysql_query() returns [true](reserved.constants.php#constant.true) on success or [false](reserved.constants.php#constant.false) on error.

The returned result resource should be passed tomysql_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 ormysql_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](reserved.constants.php#constant.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, somysql_query() fails and returns [false](reserved.constants.php#constant.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($lastname));// Perform Query <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>r</mi><mi>e</mi><mi>s</mi><mi>u</mi><mi>l</mi><mi>t</mi><mo>=</mo><mi>m</mi><mi>y</mi><mi>s</mi><mi>q</mi><msub><mi>l</mi><mi>q</mi></msub><mi>u</mi><mi>e</mi><mi>r</mi><mi>y</mi><mo stretchy="false">(</mo></mrow><annotation encoding="application/x-tex">result = mysql_query(</annotation></semantics></math>result=mysqlquery(query);// Check result // This shows the actual query sent to MySQL, and the error. Useful for debugging. if (!$result) { $message = 'Invalid query: ' . mysql_error() . "\n"; <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>m</mi><mi>e</mi><mi>s</mi><mi>s</mi><mi>a</mi><mi>g</mi><mi>e</mi><mi mathvariant="normal">.</mi><msup><mo>=</mo><mo mathvariant="normal" lspace="0em" rspace="0em">′</mo></msup><mi>W</mi><mi>h</mi><mi>o</mi><mi>l</mi><mi>e</mi><mi>q</mi><mi>u</mi><mi>e</mi><mi>r</mi><mi>y</mi><msup><mo>:</mo><mo mathvariant="normal" lspace="0em" rspace="0em">′</mo></msup><mi mathvariant="normal">.</mi></mrow><annotation encoding="application/x-tex">message .= 'Whole query: ' . </annotation></semantics></math>message.=′Wholequery:′.query; die($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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