如何从多个表的左联接中选择MAX日期

Question

I have a invoice table, credit_memo table and payments table. I am having trouble returning max date from invoice due date, payment issue date or credit memo issue date.

SELECT
  T1.b2b_id,
  MAX(T1.due_date) | coalesce(T3.issue_date, '1000-01-01') | 
    coalesce(T4.issue_date, '10001-01-01') AS endDate
FROM t_invoice AS T1
   LEFT JOIN t_linked_transaction AS T2 ON T2.invoice_uid = T1.uid
   LEFT JOIN t_payment AS T3 ON T3.uid = T2.payment_uid
   LEFT JOIN t_credit_memo AS T4 ON T4.uid = t2.credit_memo_uid

The MAX query returns 20150301009885.

The correct date is 2015-03-01 00:00:00, if I wrap the MAX query with DATE(MAX(...)) it returns NULL

Thanks for the help

Answer 1

You need to cast to Char as per MySQL bug specified in link here

MySQL Bug MAX(datetime)

SELECT
  T1.b2b_id,
  MAX (CAST(T1.due_date) AS CHAR) | coalesce(T3.issue_date, '1000-01-01') | 
    coalesce(T4.issue_date, '10001-01-01') AS endDate
FROM t_invoice AS T1
   LEFT JOIN t_linked_transaction AS T2 ON T2.invoice_uid = T1.uid
   LEFT JOIN t_payment AS T3 ON T3.uid = T2.payment_uid
   LEFT JOIN t_credit_memo AS T4 ON T4.uid = t2.credit_memo_uid