SQL - 组合 AND & OR

Question

我有以下代码:

SELECT sdd.sd_doc_classification,
       sdd.sd_title,
       sdd.sd_desc,
       sdr.sd_upload_fname
FROM sdoc_docs AS sdd
INNER JOIN sdoc_revh AS sdr ON sdd.sd_id = sdr.sd_id
WHERE (sdd.sd_title LIKE '%policy%')
    OR (sdd.sd_title LIKE '%guideline%')
    AND (sdd.sd_doc_classification NOT LIKE '%\Trust Wide Policies & Guidelines\%')

但是，添加“OR (sdd.sd_title LIKE '%guideline%')”已将其破坏，语句现在返回的值类似于' %\Trust Wide 政策和指南\%'。

删除上面的指南示例后，代码按预期运行。

基本上我想显示任何有 sd_title 的东西，比如 policy 或 guideline 而没有 sd_doc_classification 喜欢 '%trust wide pol%'。

Answer 1

AND 的优先级高于 OR - 也就是说，就好像您是这样编写查询的:

SELECT sdd.sd_doc_classification,
       sdd.sd_title,
       sdd.sd_desc,
       sdr.sd_upload_fname
FROM       sdoc_docs AS sdd
INNER JOIN sdoc_revh AS sdr ON sdd.sd_id = sdr.sd_id
WHERE      (sdd.sd_title LIKE '%policy%') OR 
           ((sdd.sd_title LIKE '%guideline%') AND 
            (sdd.sd_doc_classification NOT LIKE 
             '%\Trust Wide Policies & Guidelines\%')) 

如果你想控制评估条件的优先级，你可以自己显式地添加括号:

SELECT sdd.sd_doc_classification,
       sdd.sd_title,
       sdd.sd_desc,
       sdr.sd_upload_fname
FROM       sdoc_docs AS sdd
INNER JOIN sdoc_revh AS sdr ON sdd.sd_id = sdr.sd_id
WHERE      ((sdd.sd_title LIKE '%policy%') OR 
            (sdd.sd_title LIKE '%guideline%')) AND 
           (sdd.sd_doc_classification NOT LIKE 
             '%\Trust Wide Policies & Guidelines\%')