輕鬆完爆Helm私有倉庫
阿新 • • 發佈:2021-06-12
我就廢話不多說了,大家還是直接看程式碼吧~
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< select id = "findActiveBlogLike" resultType = "Blog" >
SELECT * FROM BLOG
WHERE
< if test = "state != null" >
state = #{state}
</ if >
</ select >
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如果state引數為空時,最終生成SQL語句為
SELECT * FROM BLOG
WHERE
執行會出錯,當然,你可以在where 後加一個1=1,改成
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< select id = "findActiveBlogLike" resultType = "Blog" >
SELECT * FROM BLOG
WHERE 1=1
< if test = "state != null" >
and state = #{state}
</ if >
</ select >
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但是這個做法不太“環保”(畢竟引入了一個垃圾條件),其實只要改成<where>...</where>即可
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< select id = "findActiveBlogLike" resultType = "Blog" >
SELECT * FROM BLOG
< where >
< if test = "state != null" >
and state = #{state}
</ if >
</ where >
</ select >
|