如何在 PHP/MYSQL 中同时执行两个 mysql 查询？

Question

I have two queries, as following:

SELECT SQL_CALC_FOUND_ROWS Id, Name FROM my_table WHERE Name LIKE '%prashant%' LIMIT 0, 10;
SELECT FOUND_ROWS();

I want to execute both these queries in a single attempt.

$result = mysql_query($query);

But then tell me how I will handle each tables set separately. Actually in ASP.NET we uses dataset which handles two queries as

ds.Tables[0];
ds.Tables[1]; .. etc

How can I do the same using PHP/MYSQL?

Answer 1

Update: Apparently possible by passing a flag to mysql_connect() . See Executing multiple SQL queries in one statement with PHP Nevertheless, any current reader should avoid using the mysql_ -class of functions and prefer PDO.

You can't do that using the regular mysql-api in PHP. Just execute two queries. The second one will be so fast that it won't matter. This is a typical example of micro optimization. Don't worry about it.

For the record, it can be done using mysqli and the mysqli_multi_query -function.

Answer 2

As others have answered, the mysqli API can execute multi-queries with the msyqli_multi_query() function.

For what it's worth, PDO supports multi-query by default, and you can iterate over the multiple result sets of your multiple queries:

$stmt = $dbh->prepare("
    select sql_calc_found_rows * from foo limit 1 ; 
    select found_rows()");
$stmt->execute();
do {
  while ($row = $stmt->fetch()) {
    print_r($row);
  }
} while ($stmt->nextRowset());

However, multi-query is pretty widely considered a bad idea for security reasons. If you aren't careful about how you construct your query strings, you can actually get the exact type of SQL injection vulnerability shown in the classic "Little Bobby Tables" XKCD cartoon . When using an API that restrict you to single-query, that can't happen.

Answer 3

You'll have to use the MySQLi extension if you don't want to execute a query twice:

if (mysqli_multi_query($link, $query))
{
    $result1 = mysqli_store_result($link);
    $result2 = null;

    if (mysqli_more_results($link))
    {
        mysqli_next_result($link);
        $result2 = mysqli_store_result($link);
    }

    // do something with both result sets.

    if ($result1)
        mysqli_free_result($result1);

    if ($result2)
        mysqli_free_result($result2);
}

Answer 4

You have to use MySQLi, below code works well

<?php
$mysqli = new mysqli("localhost", "my_user", "my_password", "world");

/* check connection */
if (mysqli_connect_errno()) {
    printf("Connect failed: %s\n", mysqli_connect_error());
    exit();
}

$query  = "SELECT CURRENT_USER();";
$query .= "SELECT Name FROM City ORDER BY ID LIMIT 20, 5";

/* execute multi query */
if ($mysqli->multi_query($query)) {
    do {
        /* store first result set */
        if ($result = $mysqli->store_result()) {
            while ($row = $result->fetch_row()) {
                printf("%s\n", $row[0]);
            }
            $result->free();
        }
        /* print divider */
        if ($mysqli->more_results()) {
            printf("-----------------\n");
        }
    } while ($mysqli->next_result());
}

/* close connection */
$mysqli->close();
?>

Answer 5

Using SQL_CALC_FOUND_ROWS you can't.

The row count available through FOUND_ROWS() is transient and not intended to be available past the statement following the SELECT SQL_CALC_FOUND_ROWS statement.

As someone noted in your earlier question, using SQL_CALC_FOUND_ROWS is frequently slower than just getting a count.

Perhaps you'd be best off doing this as as subquery:

SELECT 
 (select count(*) from my_table WHERE Name LIKE '%prashant%') 
as total_rows,
Id, Name FROM my_table WHERE Name LIKE '%prashant%' LIMIT 0, 10;

Answer 6

Like this:

$result1 = mysql_query($query1);
$result2 = mysql_query($query2);

// do something with the 2 result sets...

if ($result1)
    mysql_free_result($result1);

if ($result2)
    mysql_free_result($result2);

Answer 7

It says on the PHP site that multiple queries are NOT permitted (EDIT: This is only true for the mysql extension. mysqli and PDO allow multiple queries) . So you can't do it in PHP, BUT, why can't you just execute that query in another mysql_query call, (like Jon's example)? It should still give you the correct result if you use the same connection. Also, mysql_num_rows may help also.

Answer 8

Yes it is possible without using MySQLi extension.

Simply use CLIENT_MULTI_STATEMENTS in mysql_connect 's 5th argument.

Refer to the comments below Husni's post for more information.