Mybatis进行多条件查询之choose,when和otherwise

1.choose when otherwise 相当于if...else if...else

when至少有一个 other最多有一个（在where标签之下）

<!--List<Emp> testWhenAndChoose(Emp emp);-->
    <select id="testWhenAndChoose" resultType="emp">
        select * from t_emp
        <where>
        <choose>
            <when test="empName!=null and empName!=''">
                emp_name=#{empName}
            </when>
            <when test="age!=null and age!=''">
                age=#{age}
            </when>
            <when test="sex!=null and sex!=''">
                sex=#{sex}
            </when>
            <when test="email!=null and email!=''">
                email=#{email}
            </when>
            <otherwise>
                did=1
            </otherwise>
        </choose>
        </where>
    </select>