mysql - 如何重新编写 sql 查询

Question

我不是 sql 编程方面的专家，我想知道您是否可以帮助我使用 INNER JOIN 重新编写以下查询？

db_query("
    select max(field_date_and_time_value2) as last_time 
    from field_data_field_date_and_time 
    where (field_date_and_time_value2 > '".$today."') 
    AND (".$node->uid." = (select uid from node where nid = " . $node->nid ."))");

Answer 1

假设您的field_date_and_time表中有一个名为与表中该列uid具有相同含义的列node，这就是您需要做的。

      SELECT MAX(A.field_date_and_time_value2) AS last_time
        FROM field_date_and_time A
  INNER JOIN node B ON A.uid = B.uid
       WHERE B.nid = '".$node->nid."'
         AND A.field_date_and_time_value2 > '".$today."'

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Answer 2

像这样的东西会起作用吗？

SELECT
    max(a.field_date_and_time_value2) as last_time
    , b.uid
FROM field_data_field_date_and_time a
    INNER JOIN
        node b
    ON
        /* this piece might be wrong. what is the relationship between the first table and the second one? */
        b.nid = '".$node->nid."'
where
    a.field_date_and_time_value2 > '".$today."' AND
    b.uid = $node->nid