MyBatis 动态SQL

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

<mapper namespace="com.iotek.dao.IEmployeeDAO">
        <resultMap id="empMap" type="Employee">
                <id property="empId" column="empId"/>
                <result property="empName" column="empName"/>
                <result property="salary" column="salary"/>
                <!--association:配置多对一、property：多方中一方的属性名，javaType：一方的类型-->
                <association property="dept" javaType="Dept">
                        <id property="deptId" column="deptId"/>
                        <result property="deptName" column="deptName"/>
                </association>
        </resultMap>


        <select id="getEmpAndDeptByEmpId" parameterType="int" resultMap="empMap">
                select t_dept.*,t_employee.* from t_dept,t_employee
                    where t_dept.deptId = t_employee.dept_id
                      AND t_employee.empId = #{id}
        </select>

        <select id="getEmpByParams" parameterType="map" resultType="Employee">
                select t_employee.* from t_employee where 1=1
                <if test="empName!=null and empName!=''">
                      and  empName like #{empName}
                </if>
                <if test="minSalary!=null and minSalary>=0">
                        and salary >= #{minSalary}
                </if>
                <if test="maxSalary!=null and maxSalary>=0">
                        and salary &lt;= #{maxSalary}
                </if>
                and salary is not null
        </select>

        <select id="getEmpByParams2" parameterType="map" resultType="Employee">
                select t_employee.* from t_employee
                <where>
                        <if test="empName!=null and empName!=''">
                                and  empName like #{empName}
                        </if>
                        <if test="minSalary!=null and minSalary>=0">
                                and salary >= #{minSalary}
                        </if>
                        <if test="maxSalary!=null and maxSalary>=0">
                                and salary &lt;= #{maxSalary}
                        </if>
                </where>
                and salary is not null
        </select>

        <select id="getEmpByParams3" parameterType="map" resultType="Employee">
                select t_employee.* from t_employee
                <choose>
                        <when test="empName!=null and empName!=''">
                                where  empName like #{empName}
                        </when>
                        <when test="minSalary!=null and minSalary>=0">
                                where salary >= #{minSalary}
                        </when>
                        <when test="maxSalary!=null and maxSalary>=0">
                                where salary &lt;= #{maxSalary}
                        </when>
                        <otherwise>
                                where salary is not null
                        </otherwise>
                </choose>
        </select>

        <select id="getEmpInIds" parameterType="list" resultMap="empMap">
                select t_employee.* from t_employee
                <where>
                        empId IN
                        <foreach collection="list" item="id" open="(" close=")" separator=",">
                                #{id}
                        </foreach>
                </where>

                <!--等价于：select * from t_employee where empId in (1,2,3)-->
                <!--1,2,3就是被封装在list集合-->
        </select>

        <update id="DynamicUpdateEmployee" parameterType="Employee">
                update t_employee
                <set>
                        <if test="empName!=null and empName!=''">empName=#{empName},</if>
                        <if test="salary!=null and salary>0">salary=#{salary},</if>

                </set>
                where empId=#{empId}
        </update>
</mapper>