mysql - 根据参数选择 null 或非 null

Question

我有一个这样的查询:

    SELECT old.NPP,
       old.NAMA,
       old.JOB,
       pgh.status
    FROM a old
    LEFT JOIN b pgh ON old.person_id = pgh.person_id
                    AND pgh.periode = 2015
                    AND pgh.LAST_STATUS = 1
    WHERE old.UNIT_BESARAN = 'DIVISI TEKNOLOGI INFORMASI'
    AND pgh.status = #status
    ORDER BY pgh.status

我希望我的查询可以从 pgh status 获取每个值，比如当我输入 status 5 时，查询必须返回 status 为 5，但是当我输入 null 时，当状态为 null 时，查询将从数据库返回数据。

如何设置查询？

Answer 1

你可以这样写条件:

where old.UNIT_BESARAN = 'DIVISI TEKNOLOGI INFORMASI' and
      (pgh.status = #status or pgh.status is null and #status is null)