Question

我只是在两个条件为真时才尝试插入一行。我想在一个声明中这样做。我的表看起来像：

             [Table]                 
id, userId, locationId, type, timestamp             
---------------------------------------              
1   5   19   0   2017-03-28 03:05:48                   
2   5   19   1   2017-03-29 00:57:57

有没有办法执行以下的SQL：

LIRFU =上次插入的用户行= SELECT * FROM Table WHERE userId = $userId ORDER BY timestamp DESC LIMIT 1。

如果($userId, $locationId, 1)，则插入行LIRFU.type = 0。
如果($userId, $locationId, 0)，则插入行LIRFU.type = 1 AND LIRFU.locationId != $locationId。

Answer 1

让我们打电话给您，User_Types。

这里是如果LIRFU.type = 0插入带有样本数据（5,19,1）的行的语句：

INSERT INTO User_Types (userId, locationId, type)
SELECT @userId:=5, 19, 1 from dual
WHERE (SELECT type FROM User_Types WHERE userId = @userId ORDER BY timestamp DESC LIMIT 1) = 0;

您可以使用?替换数据，将其转换为PHP中的预准备语句。

$stmt = $db->prepare("INSERT INTO User_Types (userId, locationId, type) SELECT @userId:=?, ?, 1 from dual WHERE (SELECT type FROM User_Types WHERE userId = @userId ORDER BY timestamp DESC LIMIT 1) = 0");

$stmt->bind_param('ii', $user_id, $location_id);
//if LIRFU.type = 0

$stmt->execute();

这里是如果LIRFU.type = 1 AND LIRFU.locationId != 19插入带有样本数据（5,19,0）的行的语句：

INSERT INTO User_Types (userId, locationId, type)
SELECT @userId:=5, @locationId:=19, 0 from dual
WHERE (SELECT type FROM User_Types WHERE userId = @userId ORDER BY timestamp DESC LIMIT 1) = 1 
AND   (SELECT locationId FROM User_Types WHERE userId = @userId ORDER BY timestamp DESC LIMIT 1) <> @locationId;

用PHP编写时的相同想法：

$stmt = $db->prepare("INSERT INTO User_Types (userId, locationId, type) SELECT @userId:=?, @locationId:=?, 0 from dual WHERE (SELECT type FROM User_Types WHERE userId = @userId ORDER BY timestamp DESC LIMIT 1) = 1 AND (SELECT locationId FROM User_Types WHERE userId = @userId ORDER BY timestamp DESC LIMIT 1) <> @locationId");

$stmt->bind_param('ii', $user_id, $location_id);
//if LIRFU.type = 1 and LIRFU.locationId != $location_id

$stmt->execute();

链接Mysql查询以进行插入

1 个答案: