Mybatis 模糊查询

方式一

说明： ${} 方式不会预编译，有SQL注入的风险

     <select id="selectUserByName" resultMap="userAndRole">
        select * from users
        <where>
            <if test="status != null">
                user_state=#{status}
            </if>
            <if test="username !=null and username!=''">
                and user_name like '%${username}%'
            </if>
        </where>
    </select>

方式二

Mybatis bind 标签 + #{}

  <select id="selectUserByName" resultMap="userAndRole">
        select * from users
        <where>
            <if test="status != null">
                user_state=#{status}
            </if>
            <if test="username !=null and username!=''">
                <bind name="name" value="'%'+username+'%'" />
                and user_name like #{name}
            </if>
        </where>
    </select>

方式三

Mysql的concat + #{}

    <select id="selectUserByName" resultMap="userAndRole">
        select * from users
        <where>
            <if test="status != null">
                user_state=#{status}
            </if>
            <if test="username !=null and username!=''">
                and user_name like concat( concat('%',#{username}),'%' )
            </if>
        </where>
    </select>