java MySQL的in查询两个字段同时相等的多个数据查询
在Java中想进行下面的查询,不想写循环一条条查
select id,name,address,age from users where name='A' and address='addr1'
select id,name,address,age from users where name='B' and address='addr2'
select id,name,address,age from users where name='C' and address='addr3'
查了下,in可以使用在多个字段上
select id,name,address,age from users where (name,address) in(('A','addr1'),('B','addr2'),('C','addr3'))
在Java中
1.构建条件
List<Map<String, String>> list = new ArrayList<>(); // 创建一个新的Map对象 Map<String, String> map1 = new HashMap<>(); map1.put("name", "A"); map1.put("address", "addr1"); list.add(map1); Map<String, String> map2= new HashMap<>(); map2.put("name", "B"); map2.put("address", "addr2"); list.add(map2); Map<String, String> map3= new HashMap<>(); map3.put("name", "C"); map3.put("address", "addr3"); list.add(map3);
2.mapper接口定义
List<Map<String,Object>> getInfos(@Param("list")List<String> list);
3.mapper XML
<select id="getInfos" resultType="java.util.HashMap"> select id,name,address,age from `users` where (name,address) in <foreach item="item" index="index" collection="list" open="(" separator="," close=")"> (#{item.name},#{item.address}) </foreach> </select>
这样就可以一次查询出来了