How to reformulate an sql query

问题

i am not an expert in sql programming and i was wondering if you can help me reformulate the following query using INNER JOIN?

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 ."))");

回答1:

Would something like this work?

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

回答2:

Assuming your field_date_and_time table has a column called uid having the same meaning as that column in your node table, here's what you need to do.

      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."'

Beware SQL injection attacks! Avoid substituting variables directly into SQL statements unless you're really sure those variables can't be corrupted by badguy users! Remember the story of the guy named

"johnny ; drop tables *;"

来源：https://stackoverflow.com/questions/17655988/how-to-reformulate-an-sql-query

标签

mysql

sql

select

inner-join