mybatis动态sql

 

if 和where 动态sql(所有都要+and)

<select id="xx" resultMap="xx">

select * from user

<where> 

<if test="xx!=' ' and xx!=null">

and xxx like concat ('%',#{xxx},'%')

</if></where></select>

 

if和 trim 动态sql

若有返回值 则运行trim内容

增加前缀后缀 prefix suffix

首部忽略 首尾部忽略 prefixOverrides suffixOverrides

<select id="xx" resultType="xx">

select * from xx 

<trim prefix="where" prefixOverrides="and | or">

<if test="xx!=null">

and xxx like concat ('%',#{xx},'%')

</if></trim>

 

if和set

<update id="xx" parameterType="xx">

update xx 

<set>

<if test="xxx!=null">xxx=#{xxx},</if>

</set>

 

foreach

choose

otherwise