为什么使用事务时 multi_query 不起作用？

Question

这是一个例子。

$mysqli = new mysqli("localhost", "root", "123", "temp");

$mysqli->begin_transaction();

$sql1 = "insert into test (Name) values ('pratik5');";
$sql1 .= "insert into test (Name) values ('pratik6');";

$test = $mysqli->multi_query($sql1);

$mysqli->commit();

两个查询中都没有任何错误，但是在调用时commit()这些值并未存储在数据库中。如果拆分为单独的查询并通过query().

Answer 1

$mysqli->multi_query($sql1);
$mysqli->commit(); // This will result in a "Commands out of sync; you can't run this command now" error.

上面的内容等同于：

$mysqli->multi_query($sql1);
$mysqli->query("commit"); // This will result in a "Commands out of sync; you can't run this command now" error.

无论你输入什么$mysqli->query("...");，它都会导致"Commands out of sync"错误，即使是简单的SELECT 1;

此错误的原因是因为->commit()操作运行单个查询 ( commit;)。但之前查询的结果还没有被读取。

当使用单个query()操作时，MySQL服务器将根据查询语句以响应帧进行应答。

使用时multi_query()，在 MySQL 通信协议级别会发生以下情况：

1. 发送“Request Set Option”（如 Wireshark 中显示的）帧，并将“multi statements”标志设置为ON。
2. multi_query()包含作为请求传输的整个字符串的帧。
3. MySQL 服务器以可能包含不同结果集的响应进行应答。调用存储过程时也是如此。

解决方案1

如果您想使用multi_query()，则必须将start transaction/commit操作作为其中的一部分：

$mysqli = new mysqli("localhost", "root", "123", "temp");

$sql1 = "start transaction;"; // $mysqli->begin_transaction() is a convenience function for simply doing this.
$sql1 .= "insert into test (Name) values ('pratik5');";
$sql1 .= "insert into test (Name) values ('pratik6');";
$sql1 .= "commit;"; // $mysqli->commit() is a convenience function for simply doing this.

$mysqli->multi_query($sql1);

/* As in "Solution 2", if you plan to perform other queries on DB resource
   $mysqli after this, you must consume all the resultsets:
// This loop ensures that all resultsets are processed and consumed:
do {
    $mysqli->use_result();
}
while ($mysqli->next_result());
*/

解决方案2

$mysqli = new mysqli("localhost", "root", "123", "temp");

$mysqli->begin_transaction();

$sql1 = "insert into test (Name) values ('pratik5');";
$sql1 .= "insert into test (Name) values ('pratik6');";

$mysqli->multi_query($sql1);

// This loop ensures that all resultsets are processed and consumed:
do {
    $mysqli->use_result();
}
while ($mysqli->next_result());

// Now that all resultsets are processed, a single query `commit;` can happen:
$mysqli->commit();

MySQL 参考：“命令不同步”。

Answer 2

您不应该使用多重查询。重写你的代码如下

$mysqli->begin_transaction();

$mysqli->query("insert into test (Name) values ('pratik5')");
$mysqli->query("insert into test (Name) values ('pratik6')");

$mysqli->commit();

或者，对于现实生活中的插入，

$mysqli->begin_transaction();

$stmt = $mysqli->prepare("insert into test (Name) values (?)");
$stmt->bind_param("s", $name);
$name = 'pratik5';
$stmt->execute();
$name = 'pratik6';
$stmt->execute();

$mysqli->commit();