1.sql语句标签 <sql></sql><include></include>
<sql id="someFied">
name,password,age,sex,phone
</sql>
<select id="selectData">
select
<include refid="someFied">
from xxx
where id=#{id}
</select>
2.if标签 if判断
<select id="selectData" resultType="Product">
select * from product
<if test="name!=null">
where name like concat('%',#{name},'%')
</if>
</select>
3.<when> <otherwise>标签
Mybatis里面没有else标签，但是可以使用when otherwise标签来达到这样的效果
<select id="listProduct" resultType="Product">
SELECT * FROM product_
<where>
<choose>
<when test="name != null">
and name like concat('%',#{name},'%'</when>
<when test="price !=null and price != 0">
and price > #{price}</when> <otherwise>
and id >1</otherwise>
</choose>
</where>
</select>
4.where标签 where标签里面成立就执行，如果不成立就可以忽略wherer标签
<select id="selectData" resultType="Product">
select * from product
<where>
<if test="name!=null">
and name like concat('%',#{name},'%')
</if>
<if test="price!=null and price!=0">
and price>#{price}
</if>
</where>
</select>
5.set标签 与where标签类似,成立时执行，不成立时可以忽略
update的sql语句中会碰到多个字段，可以使用set标签
<update id="updataData" parameterType="Product">
update prduct
<set>
<if test="name!=null">name=#{name},</if>
<if test="price!=null">price=#{price}</if>
</set>
where id=#{id}
</update>
6.foreach标签，通常用于in这样的语法里
接收一个List集合时使用foreach标签循环遍历
<select if ="selectData" resultType="Product">
select * from produce
where id in
<foreach item="item" index="index" collection="list">
open="(" separator="," close=")">
#{item}
</foreach>
</select>
7.bind标签，就像是再做一次字符串拼接，网上也有说绑定，差不多意思
<select id="listProduct" resultType="Product">
<bind name="likename" value="'%' + name + '%'" />
select * from product_ where name like #{likename}
</select>