mysql - 更新列显示 mysql 中的语法错误

Question

UPDATE datanyc_new t2
SET    Prevclose = t1.Last
FROM   datanyc t1
WHERE  t2.Symbol = t1.Symbol
AND    t2.`Timestamp` = '2020-01-03'
AND    t1.`Timestamp` = ( SELECT max( Timestamp ) FROM datanyc WHERE Timestamp= '2020-01-03')

这是我使用的查询。

Answer 1

多表语法:对于mysql来说是

UPDATE [LOW_PRIORITY] [IGNORE] table_references
    SET assignment_list
    [WHERE where_condition]

https://dev.mysql.com/doc/refman/8.0/en/update.html

假设问题已正确标记，请尝试

UPDATE datanyc_new dn join datanyc d on dn.Symbol = d.Symbol
SET    Prevclose = d.Last
WHERE  dn.`Timestamp` = '2020-01-03'
  AND  d.`Timestamp` = ( SELECT max(Timestamp) FROM datanyc WHERE Timestamp= '2020-01-03');

我没有看到子查询的要点，或者可能是不正确的，如果时间戳列包含日期时间并且目的是获取 2020-01-03 的最后一次时间，那么 where 不正确并且将返回 null 你可能需要WHERE date(timestamp) = '2020-01-03'