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%')”会破坏它，现在语句会返回的值，如'%\Trust Wide Policies & Guidelines\%'。

在删除上面的指南示例后，代码按预期运行。

基本上我想要显示sd_title或policy guideline并且没有sd_doc_classification '%trust wide pol%'的任何内容。

Answer 1

AND的优先级高于OR - 也就是说，就像您编写了这样的查询一样：

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\%'))

如果要控制评估条件的优先级，可以自己显式添加括号：

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\%')

Answer 2

正如Gordon和dnoeth所指出的那样，你的括号是个问题。我认为你实际上需要以下查询。

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\%'

我发现正确地标出了不同的OR和AND子句，使它们更容易可视化和理解。

SQL - 结合AND＆amp;要么

2 个答案: