存储过程的php PDO结果为空

Question

这里有一个例子：

SQL：

CREATE PROCEDURE my_sp(
  IN in_var VARCHAR(32)
)
BEGIN

     -- This is to avoiding the next problem:
     -- If I USE bellow: EXECUTE USING in_var NOT WORK
     -- But IF I USE: EXECUTE USING @user_invar WORKING GOOD
     SET @user_invar = in_var;

    SET @query = "SELECT * FROM my_table  WHERE my_column = ? LIMIT 1;";

    PREPARE stmt FROM @query;
    EXECUTE stmt USING @user_invar;
     SET @founded_rows = FOUND_ROWS();
    DEALLOCATE PREPARE stmt;

    IF(@founded_rows = 0)THEN
        SELECT 'ZERO_REZULTS' AS RESULTS;
    END IF;  
END;

PHP：

$dbh = new PDO( $connection_params );

$sql = "CALL my_sp( :in_var )";
$stmt = $dbh->prepare( $sql );
$stmt->execute( array( ':in_var' => $_POST['in_var'] ) );
$rows = $stmt->fetchAll(PDO::FETCH_ASSOC);

//No errors but $rows is an empty array if @founded_rows is 0
//espected RESULTS = ZERO_REZULTS

奇怪的是，如果我从 phpmyadmin 界面执行过程 my_sp() ，则该过程会按预期工作。我得到了：

RESULTS = ZERO_REZULTS

已编辑：

除了@Bill Karwin 的回答之外，要按预期工作，该过程必须在 stmt 中具有最后一个 SELECT，如下所示：

CREATE PROCEDURE my_sp(
  IN in_var VARCHAR(32)
)
BEGIN

SET @user_invar = in_var;

SET @query = "SELECT * FROM my_table  WHERE my_column = ? LIMIT 1;";

PREPARE stmt FROM @query;
EXECUTE stmt USING @user_invar;
SET @founded_rows = FOUND_ROWS();
IF(@founded_rows = 0)THEN
    SELECT 'ZERO_REZULTS' AS RESULTS;
END IF;  
DEALLOCATE PREPARE stmt;

结束；

Answer 1

查询需要相同数量的列的建议不是问题。存储过程生成多个不同的结果集，而不是 UNION。

第一个 SELECT 生成零行的结果集。您仍然必须fetchAll() 才能使用此行集，即使它是“空的”。然后你必须使用nextRowset() 前进到proc 返回的下一个行集。

$dbh = new PDO( $connection_params );

$sql = "CALL my_sp( :in_var )";
$stmt = $dbh->prepare( $sql );
$stmt->execute( array( ':in_var' => $_POST['in_var'] ) );

do {
    $rowset = $stmt->fetchAll(PDO::FETCH_ASSOC);
    if ($rowset) {
        ...do something with rowset...
    }
} while ($stmt->nextRowset());

另请参阅：http://php.net/manual/en/pdostatement.nextrowset.php