关于内左更新列加入

Question

我想不出该怎么办内左此查询加入更新（这是选择查询什么工作）：

SELECT
    *
FROM
    emr AS e
    LEFT JOIN visit_ltnot AS v ON e.guid = v._pn
WHERE
    closedate='12-31-79' AND pat='00000906' AND apptstatus=''
    AND v.pdate='' AND emrdate <= '2013-11-26';

我需要更新电子病历表closedate。

我已经追平以下查询：

UPDATE emr
FROM
    emr AS e
    LEFT JOIN visit_ltnot AS v ON e.guid = v._pn SET closedate=''
WHERE
    closedate='12-31-79' AND pat='00000906' AND apptstatus=''
    AND v.pdate='' AND emrdate <= '2013-11-26';

UPDATE emr
    SET closedate=''
FROM
    emr AS e
    LEFT JOIN visit_ltnot AS v ON e.guid = v._pn
WHERE
    closedate='12-31-79' AND pat='00000906' AND apptstatus=''
    AND v.pdate='' AND emrdate <= '2013-11-26';

我得到的语法错误，我需要更新closedate值。

Answer 1

如果你正在使用MySQL，那么这应该工作：

UPDATE emr e LEFT JOIN
       visit_ltnot v
       ON e.guid = v._pn
    SET closedate = ''
    WHERE closedate = '12-31-79' AND
          pat = '00000906' AND
          apptstatus = '' AND
          v.pdate = '' AND
          emrdate <= '2013-11-26';

笔记：

• 最重要的是，UPDATE没有MySQL中的FROM条款。
• 条件v.pdate被转动外连接到内连接。所以，你还不如用inner join。
• 你不应该使用日期格式，如'12-31-79'。正确的日期格式是'1979-12-31'。
• 日期不应该被存储为字符串，因此v.pdate = ''没有意义。