1.通过trim格式化标记set或where功能
2.对于set自动删除最后一个“,”,对于where自动删除最后一个“and|or”
使用示例如下:
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select * from user
<trim prefix= "WHERE" prefixOverride= "AND |OR" >
<if test= "userName != null and userName.length()>0" > AND user_name=#{userName}</if>
<if test= "loginName != null and loginName.length()>0" > AND login_name=#{loginName}</if>
</trim>
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如果userName 为空则最终SQL为:
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select * from user where login_name = 'xx'
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prefix:
前缀
prefixOverride:
去掉第一个and或者是or
2、
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update user
<trim prefix= "set" suffixOverride= "," suffix= " where user_id = #{userId} " >
<if test= "userName != null and userName.length()>0" > user_name=#{userName} , </if>
<if test= "loginName != null and loginName.length()>0" > login_name=#{loginName} , </if>
</trim>
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如果userName 为空则最终SQL为:
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update user set login_name= 'xx' where user_id= 'xx'
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suffixOverride:
去掉最后一个逗号(也可以是其他的标记,就像是上面前缀中的and一样)
suffix:
后缀
补充:mybatis去除多余的and或者or
啥也不多说了,大家还是直接看代码吧~
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< select id= "selectBySelective" resultType= "xxx.UserInfo" >
select
<include refid= "Base_Column_List" />
from uc_user
<trim prefix= "WHERE (" suffix= ")" prefixOverrides= "AND |OR " >
<if test= "userName != null" >
user_name = #{userName}
</if>
<if test= "email != null" >
or email = #{email}
</if>
<if test= "phone != null" >
or phone = #{phone}
</if>
<if test= "weiboId != null" >
or weibo_id = #{weiboId}
</if>
<if test= "wxId != null" >
or wx_id = #{wxId}
</if>
<if test= "qqId != null" >
or qq_id = #{qqId}
</if>
</trim>
and status = 1
</ select >
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以上为个人经验,希望能给大家一个参考,也希望大家多多支持服务器之家。如有错误或未考虑完全的地方,望不吝赐教。
原文链接:https://blog.csdn.net/u012382791/article/details/95201173