Mybatis学习——动态sql

在mapper.xml文件中使用 标签实现动态sql

　　和标签

　　　　　　　　....

<?xml version="1.0" encoding="UTF-8" ?>
DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://www.mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="xyz.javaswing.mapper.UserMapper">
    <select id="findUserById" parameterType="int" resultType="user">
        select * from user where id = #{id}
    select>

    <select id="findUser" parameterType="user" resultType="user">
        select * from user
        <where>
            <if test="id!=0">
                id = #{id}
            if>
            <if test="username!=null">
                username = #{username}
            if>
            <if test="password!=null">
                password = #{password}
            if>
        where>
    select>
mapper>