我有一个存储过程IsUserPresent，类似于：
DELIMITER $$
CREATE PROCEDURE IsUserPresent(
in userid varchar (150),
out isPresent bit
)
BEGIN
SET isPresent=0;
SELECT COUNT(*)
INTO isPresent
FROM users_table
WHERE users_table.userid=userid;
END$$
我想使用mysqli准备的语句从PHP调用它。我是按照代码片段来做的，但它给了我警告。
$connect=&ConnectDB();
$stmt=$connect->prepare("CALL IsUserPresent(?,?)");
$stmt->bind_param('si',$uid,$userCount);
$stmt->execute();
$toRet = $userCount!=0;
Disconnect($connect);
return $toRet;
警告如下：
Premature end of data (mysqlnd_wireprotocol.c:1112)
Warning: mysqli_stmt::execute(): RSET_HEADER packet 1 bytes shorter than expected
Warning: mysqli_stmt::execute(): Error reading result set's header
存储过程处理已准备语句的方式有点复杂。PHP手册指出，您必须使用会话变量（MySQL会话，而不是PHP）
INOUT/OUT参数
使用会话变量访问INOUT/OUT参数的值。
所以你可以用
$connect=&ConnectDB();
// bind the first parameter to the session variable @uid
$stmt = $connect->prepare('SET @uid := ?');
$stmt->bind_param('s', $uid);
$stmt->execute();
// bind the second parameter to the session variable @userCount
$stmt = $connect->prepare('SET @userCount := ?');
$stmt->bind_param('i', $userCount);
$stmt->execute();
// execute the stored Procedure
$result = $connect->query('call IsUserPresent(@uid, @userCount)');
// getting the value of the OUT parameter
$r = $connect->query('SELECT @userCount as userCount');
$row = $r->fetch_assoc();
$toRet = ($row['userCount'] != 0);
备注：
我建议将此过程重写为具有一个返回INT.