Question

如何更改此SQL以执行以下操作：

如果用户不在表中，请添加它们。 [本部分工作]
如果用户在表中并且favourite_active = 0将其更改为favourite_active = 1。
如果用户在表格中并且favourite_active = 1将其更改为favourite_active = 0。

我需要添加WHERE子句。

$result = mysql_query("SELECT * FROM tbl_favourites WHERE (user_id = '$who' AND favourite_id = '$usernum' AND favourite_active = '1')");

// if user does not exist in favourites, add them
    if(mysql_num_rows($result) == 0) 
    {
         mysql_query("INSERT INTO tbl_favourites (user_id, favourite_id, favourite_active) VALUES ('$who', '$usernum', '1')");
        echo"You have added this user as a favourite";
    } 

// if user does exist and favourite_active = 1 change to 0
    else {
        mysql_query("UPDATE tbl_favourites SET favourite_active='0' WHERE user_id='$who' AND favourite_id='$usernum'"); 
        echo"You have removed this user as a favourite";
    }

// if user does NOT exist and favourite_active = 0 change to 1
    else {
        mysql_query("UPDATE tbl_favourites SET favourite_active='1' WHERE user_id='$who' AND favourite_id='$usernum'"); 
        echo"You have removed this user as a favourite";
    }

Answer 1

您在IF中不能有两个else子句。并且您无法在两个单独的查询中执行UPDATE，因为第二个查询只会撤消第一个查询。使用以下查询：

UPDATE tbl_favourites SET favourite_active = NOT favourite_active WHERE user_id = '$who' and `favourite_id = '$usernum'

我也不确定你说的第一部分是否有效。您的SELECT查询专门针对favourite_active = 1。如果用户已与favourite_active = 0存在，您将尝试INSERT他们。这真的是你想要的吗？也许你应该删除AND favourite_active = '1'。

如果user_id和favourite_id在表格上形成唯一索引，您可以在一个查询中执行整个操作：

INSERT INTO tbl_favourites (user_id, favourite_id, favourite_active)
VALUES ('$who', '$usernum', '1')
ON DUPLICATE KEY UPDATE favourite_active = NOT favourite_active

SQL部分工作但需要一些WHERE子句 - 我想

1 个答案: