一、wapper介紹
Wrapper ： 條件構造抽象類，最頂端父類
AbstractWrapper ： 用于查詢條件封裝，生成 sql 的 where 條件
QueryWrapper ： Entity 物件封裝操作類，不是用lambda語法
UpdateWrapper ： Update 條件封裝，用于Entity物件更新操作
AbstractLambdaWrapper ： Lambda 語法使用 Wrapper統一處理決議 lambda 獲取 column，
LambdaQueryWrapper ：看名稱也能明白就是用于Lambda語法使用的查詢Wrapper
LambdaUpdateWrapper ： Lambda 更新封裝Wrapper
@RunWith(SpringRunner.class)
@SpringBootTest
public class QueryWrapperTests {
@Autowired
private UserMapper userMapper;
}
二、AbstractWrapper
注意：以下條件構造器的方法入參中的 column 均表示資料庫欄位
1、ge、gt、le、lt、isNull、isNotNull
@Test
public void testDelete() {
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper
.isNull("name")
.ge("age", 12)
.isNotNull("email");
int result = userMapper.delete(queryWrapper);
System.out.println("delete return count = " + result);
}
SQL：UPDATE user SET deleted=1 WHERE deleted=0 AND name IS NULL AND age >= ? AND email IS NOT NULL
2、eq、ne
注意：seletOne回傳的是一條物體記錄，當出現多條時會報錯
@Test
public void testSelectOne() {
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.eq("name", "Tom");
User user = userMapper.selectOne(queryWrapper);
System.out.println(user);
}
SELECT id,name,age,email,create_time,update_time,deleted,version FROM user WHERE deleted=0 AND name = ?
3、between、notBetween
包含大小邊界
@Test
public void testSelectCount() {
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.between("age", 20, 30);
Integer count = userMapper.selectCount(queryWrapper);
System.out.println(count);
}
SELECT COUNT(1) FROM user WHERE deleted=0 AND age BETWEEN ? AND ?
4、allEq
@Test
public void testSelectList() {
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
Map<String, Object> map = new HashMap<>();
map.put("id", 2);
map.put("name", "Jack");
map.put("age", 20);
queryWrapper.allEq(map);
List<User> users = userMapper.selectList(queryWrapper);
users.forEach(System.out::println);
}
5、like、notLike、likeLeft、likeRight
selectMaps回傳Map集合串列
@Test
public void testSelectMaps() {
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper
.notLike("name", "e")
.likeRight("email", "t");
List<Map<String, Object>> maps = userMapper.selectMaps(queryWrapper);//回傳值是Map串列
maps.forEach(System.out::println);
}
SELECT id,name,age,email,create_time,update_time,deleted,version
FROM user WHERE deleted=0 AND name NOT LIKE ? AND email LIKE ?
6、in、notIn、inSql、notinSql、exists、notExists
in、notIn：
- notIn("age",{1,2,3})--->age not in (1,2,3)
- notIn("age", 1, 2, 3)--->age not in (1,2,3)
inSql、notinSql：可以實作子查詢 - 例: inSql("age", "1,2,3,4,5,6")--->age in (1,2,3,4,5,6)
- 例: inSql("id", "select id from table where id < 3")--->id in (select id from table where id < 3)
@Test
public void testSelectObjs() {
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
//queryWrapper.in("id", 1, 2, 3);
queryWrapper.inSql("id", "select id from user where id < 3");
List<Object> objects = userMapper.selectObjs(queryWrapper);//回傳值是Object串列
objects.forEach(System.out::println);
}
SELECT id,name,age,email,create_time,update_time,deleted,version
FROM user WHERE deleted=0 AND id IN (select id from user where id < 3)
7、or、and
注意：這里使用的是 UpdateWrapper
不呼叫or則默認為使用 and 連
@Test
public void testUpdate1() {
//修改值
User user = new User();
user.setAge(99);
user.setName("Andy");
//修改條件
UpdateWrapper<User> userUpdateWrapper = new UpdateWrapper<>();
userUpdateWrapper
.like("name", "h")
.or()
.between("age", 20, 30);
int result = userMapper.update(user, userUpdateWrapper);
System.out.println(result);
}
UPDATE user SET name=?, age=?, update_time=? WHERE deleted=0 AND name LIKE ? OR age BETWEEN ? AND ?
8、嵌套or、嵌套and
這里使用了lambda運算式，or中的運算式最后翻譯成sql時會被加上圓括號
@Test
public void testUpdate2() {
//修改值
User user = new User();
user.setAge(99);
user.setName("Andy");
//修改條件
UpdateWrapper<User> userUpdateWrapper = new UpdateWrapper<>();
userUpdateWrapper
.like("name", "h")
.or(i -> i.eq("name", "李白").ne("age", 20));
int result = userMapper.update(user, userUpdateWrapper);
System.out.println(result);
}
UPDATE user SET name=?, age=?, update_time=?
WHERE deleted=0 AND name LIKE ?
OR ( name = ? AND age <> ? )
9、orderBy、orderByDesc、orderByAsc
@Test
public void testSelectListOrderBy() {
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.orderByDesc("id");
List<User> users = userMapper.selectList(queryWrapper);
users.forEach(System.out::println);
}
SELECT id,name,age,email,create_time,update_time,deleted,version
FROM user WHERE deleted=0 ORDER BY id DESC
10、last
直接拼接到 sql 的最后
注意：只能呼叫一次,多次呼叫以最后一次為準 有sql注入的風險,請謹慎使用
@Test
public void testSelectListLast() {
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.last("limit 1");
List<User> users = userMapper.selectList(queryWrapper);
users.forEach(System.out::println);
}
SELECT id,name,age,email,create_time,update_time,deleted,version
FROM user WHERE deleted=0 limit 1
11、指定要查詢的列
@Test
public void testSelectListColumn() {
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.select("id", "name", "age");
List<User> users = userMapper.selectList(queryWrapper);
users.forEach(System.out::println);
}
SELECT id,name,age FROM user WHERE deleted=0
12、set、setSql
最終的sql會合并 user.setAge()，以及 userUpdateWrapper.set() 和 setSql() 中 的欄位
@Test
public void testUpdateSet() {
//修改值
User user = new User();
user.setAge(99);
//修改條件
UpdateWrapper<User> userUpdateWrapper = new UpdateWrapper<>();
userUpdateWrapper
.like("name", "h")
.set("name", "老李頭")//除了可以查詢還可以使用set設定修改的欄位
.setSql(" email = '[email protected]'");//可以有子查詢
int result = userMapper.update(user, userUpdateWrapper);
}
UPDATE user SET age=?, update_time=?, name=?, email = '[email protected]' WHERE deleted=0 AND name LIKE ?
轉載請註明出處，本文鏈接：https://www.uj5u.com/houduan/507118.html
標籤：Java
上一篇：02-MyBatisPlus入門