Mybatis多参数查询与列表查询不同方式实现
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一、查询所有数据,返回List
查询出列表,也就是返回list, 在我们这个例子中也就是 List<Employeer> , 这种方式返回数据,需要在Employeer.xml 里面配置返回的类型 resultMap, 注意不是 resultType, 而这个resultMap 所对应的应该是我们自己配置的
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- <resultMap type="Employeer" id="resultMap">
- <id property="employeer_id" column="employeer_id"/>
- <result property="employeer_name" column="employeer_name"/>
- <result property="employeer_age" column="employeer_age"/>
- <result property="employeer_department" column="employeer_department"/>
- <result property="employeer_worktype" column="employeer_worktype"/>
- </resultMap>
id、result是最简单的映射,id为主键映射;result其他基本数据库表字段到实体类属性的映射。查询列表的语句在 Employeer.xml 中
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- <select id="findEmployeerByName" parameterType="string" resultMap="resultMap">
- select * from `t_employeer` where employeer_name like #{employeer_name}
- </select>
在EmployeerMapper 接口中增加方法:public List<Employeer> findEmployeerByName(String employeer_name); -
-
-
- public List<Employeer> findEmployeerByName(String employeer_name);
测试:-
-
-
- public static List<Employeer> getEmployeerList(String employeer_name){
- SqlSession session = null;
- List<Employeer> employeers=null;
- try {
- session = sqlSessionFactory.openSession();
- EmployeerMapper employeerMapper=session.getMapper(EmployeerMapper.class);
- employeers = employeerMapper.findEmployeerByName(employeer_name);
- session.commit() ;
- } finally {
- session.close();
- }
- return employeers;
-
- }
- public static void main(String[] args) {
- List<Employeer> employeers=getEmployeerList("张三");
- for(Employeer employeer:employeers){
- System.out.println(employeer);
- }
-
- }
结果:
其中的数据的之前插入的,现在要查找张三的列表全部都列出来了。
二、多参数查询
(1)方法一
EmployeerMapper中定义
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-
-
- public List<Employeer> findEmployeerByNameandDep(String employeer_name,String employeer_department);
Employeer.xml中定义-
- <resultMap type="Employeer" id="resultMap">
- <id property="employeer_id" column="employeer_id"/>
- <result property="employeer_name" column="employeer_name"/>
- <result property="employeer_age" column="employeer_age"/>
- <result property="employeer_department" column="employeer_department"/>
- <result property="employeer_worktype" column="employeer_worktype"/>
- </resultMap>
- <!--多参数 查找 返回list 的select 语句,注意 resultMap 的值是指向前面定义好的 -->
- <select id="findEmployeerByNameandDep" resultMap="resultMap">
- select* from `t_employeer` where employeer_name=#{0} and employeer_department=#{1}
- </select>
由于是多参数那么就不能使用parameterType, 改用#{index}是第几个就用第几个的索引,索引从0开始
测试代码:
-
-
-
- public static List<Employeer> getEmployeerList(String employeer_name,String employeer_department){
- SqlSession session = null;
- List<Employeer> employeers=null;
- try {
- session = sqlSessionFactory.openSession();
- EmployeerMapper employeerMapper=session.getMapper(EmployeerMapper.class);
- employeers = employeerMapper.findEmployeerByNameandDep(employeer_name, employeer_department);
- session.commit() ;
- } finally {
- session.close();
- }
- return employeers;
-
- }
- public static void main(String[] args) {
- System.out.println("=========================使用多单参数查询===========================");
- List<Employeer> employeers1=getEmployeerList("张三","产品二部");
- for(Employeer employeer1:employeers1){
- System.out.println(employeer1);
- }
结果:
方法二:
将 resultMap="resultMap" 改成 resultType="Employeer"
- <!--多参数 查找 返回list 的select 语句,注意 resultMap 的值是指向前面定义好的 -->
- <select id="findEmployeerByNameandDep" resultType="Employeer">
- select* from `t_employeer` where employeer_name=#{0} and employeer_department=#{1}
- </select>
方法三:Map封装多参数EmployeerMapper.java中添加-
-
-
- public List<Employeer> findEmployeerByNameandDep1(Map<String,String> map);
Employeer.xml中添加:-
- <select id="findEmployeerByNameandDep1" parameterType="map" resultType="Employeer">
- select* from `t_employeer` where employeer_name=#{key1} and employeer_department=#{key2}
- </select>
其中map是mybatis自己配置好的直接使用就行。map中key的名字是那个就在#{}使用那个。测试使用:
-
-
-
- public static List<Employeer> getEmployeerList(Map<String, String> map){
- SqlSession session = null;
- List<Employeer> employeers=null;
- try {
- session = sqlSessionFactory.openSession();
- EmployeerMapper employeerMapper=session.getMapper(EmployeerMapper.class);
- employeers = employeerMapper.findEmployeerByNameandDep1(map);
- session.commit() ;
- } finally {
- session.close();
- }
- return employeers;
-
- }
- System.out.println("=========================使用多单参数map方式查询===========================");
- Map<String, String> map = new HashMap<String, String>();
- map.put("key1", "明明");
- map.put("key2", "财会部");
- List<Employeer> employeers2=getEmployeerList(map);
- for(Employeer employeer2:employeers2){
- System.out.println(employeer2);
- }
一定要注意key:结果:
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