mybatis的sql标签使用

1、sql标签定义

<sql id="userColumns"> ${alias}.id,${alias}.username,${alias}.password </sql>

2、sql标签引用

<select id="selectUsers" resultType="map">select<include refid="userColumns"><property name="alias" value="t1"/></include>,<include refid="userColumns"><property name="alias" value="t2"/></include>  from some_table t1cross join some_table t2</select>

3、属性使用

<sql id="sometable">  ${prefix}Table</sql><sql id="someinclude">  from    <include refid="${include_target}"/></sql><select id="select" resultType="map">  select    field1, field2, field3  <include refid="someinclude">    <property name="prefix" value="Some"/>    <property name="include_target" value="sometable"/>  </include></select>