gt、ge、lt、le、isNull、isNotNull
大于 >
例: gt("age", 18) → age > 18
ge 大于等于 >=
例: ge("age", 18) → age >= 18
lt 小于 <
例: lt("age", 18) → age < 18
le 小于等于 <=
例: le("age", 18) → age <= 18
isNUll 字段 IS NULL
例: isNull("name") → name is null
isNotNull 字段 IS NOT NULL
例: isNotNull("name") → name is not null
@Test
public void queryWrapperOne() {
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.
isNull("name")
.ge("age", 23)
.isNotNull("email");
// 逻辑删除
int result = userMapper.delete(queryWrapper);
System.out.println(result);
// 最终的语句为：UPDATE user SET deleted=1 WHERE deleted=0 AND name IS NULL AND age >= ? AND email IS NOT NULL
}
eq、ne
eq 等于 =
例: eq("name", "老王") → name = '老王'
ne 不等于 <>
例: ne("name", "老王") → name <> '老王'
@Test
public void queryWrapperTwo() {
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.eq("name", "BNTang");
// selectOne：返回的是一条记录，当出现多条时会报错
User user = userMapper.selectOne(queryWrapper);
System.out.println(user);
}
between、notBetween
BETWEEN 值1 AND 值2
例: between("age", 18, 30) → age between 18 and 30
NOT BETWEEN 值1 AND 值2
例: notBetween("age", 18, 30) → age not between 18 and 30
allEq
allEq 全部 eq(或个别 isNull)
个别参数说明：
params: key 为数据库字段名, value 为字段值
如果想表示 null isNull，则在 value 取值的时候传入一个 null, 为 null 时调用 isNull 方法, 为false时则忽略value为null的，也就是不拼接 value 为 null 的查询条件字段
例1: allEq({id:1,name:"老王",age:null})→id = 1 and name = '老王' and age is null
例2: allEq({id:1,name:"老王",age:null}, false)→id = 1 and name = '老王'
@Test
public void queryWrapperFour() {
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
Map<String, Object> queryParamsMap = new HashMap<>();
queryParamsMap.put("id", 1373266771933462530L);
queryParamsMap.put("name", "BNTang");
queryParamsMap.put("age", 23);
queryWrapper.allEq(queryParamsMap);
List<User> users = userMapper.selectList(queryWrapper);
users.forEach(System.out::println);
}
个别参数说明
filter: 过滤函数, 是否允许字段传入比对条件中
params 与 null、IsNull 同上
例1: allEq((k,v) -> k.indexOf("a") >= 0, {id:1,name:"老王",age:null})→name = '老王' and age is null
例2: allEq((k,v) -> k.indexOf("a") >= 0, {id:1,name:"老王",age:null}, false)→name = '老王'
如上图可看到，只添加了一个 id 查询的条件因为我写的过滤条件为要包含 i 这个字符串，所以只有第一个 key, value 包含了所以就只添加了 id
like、notLike、likeLeft、likeRight
LIKE '%值%'
例: like("name", "王")→name like '%王%'
NOT LIKE '%值%'
例: notLike("name", "王")→name not like '%王%'
LIKE '%值'
例: likeLeft("name", "王")→name like '%王'
LIKE '值%'
例: likeRight("name", "王")→name like '王%'
@Test
public void queryWrapperFive() {
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper
.notLike("name", "BNTang")
.likeRight("email", "zq");
// 返回值是Map列表
List<Map<String, Object>> users = userMapper.selectMaps(queryWrapper);
users.forEach(System.out::println);
}
in、notIn、inSql、notinSql、exists、notExists
字段 IN (value.get(0), value.get(1), ...)
例: in("age",{1,2,3})→age in (1,2,3)
字段 NOT IN (value.get(0), value.get(1), ...)
例: notIn("age",{1,2,3})→age not in (1,2,3)
字段 IN ( sql语句 )
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)
字段 NOT IN ( sql语句 )
例: notInSql("age", "1,2,3,4,5,6")→age not in (1,2,3,4,5,6)
例: notInSql("id", "select id from table where id < 3")→id not in (select id from table where id < 3)
拼接 EXISTS ( sql语句 )
例: exists("select id from table where age = 1")→exists (select id from table where age = 1)
拼接 NOT EXISTS ( sql语句 )
例: notExists("select id from table where age = 1")→not exists (select id from table where age = 1)
@Test
public void queryWrapperSix() {
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.in("id", 1, 2, 3);
queryWrapper.inSql("id", "select id from user where id < 3");
// 返回值是Object列表
List<Object> users = userMapper.selectObjs(queryWrapper);
users.forEach(System.out::println);
}
or、and
拼接 OR
注意事项：
主动调用or表示紧接着下一个方法不是用and连接!(不调用or则默认为使用and连接)
例: eq("id",1).or().eq("name","老王")→id = 1 or name = '老王'
OR 嵌套
例: or(i -> i.eq("name", "李白").ne("status", "活着"))→or (name = '李白' and status <> '活着')
AND 嵌套
例: and(i -> i.eq("name", "李白").ne("status", "活着"))→and (name = '李白' and status <> '活着')
@Test
public void queryWrapperSeven() {
// 修改值
User user = new User();
user.setAge(99);
user.setName("BNTang6666");
// 修改条件
UpdateWrapper<User> userUpdateWrapper = new UpdateWrapper<>();
userUpdateWrapper
.like("name", "BNTang")
.or()
.between("age", 20, 30);
int result = userMapper.update(user, userUpdateWrapper);
System.out.println(result);
}
嵌套 or、嵌套 and
@Test
public void queryWrapperEight() {
// 修改值
User user = new User();
user.setAge(99);
user.setName("BNTang6666");
// 修改条件
UpdateWrapper<User> userUpdateWrapper = new UpdateWrapper<>();
userUpdateWrapper
.like("name", "A")
.or(i -> i.eq("name", "BNTang6666").ne("age", 20));
int result = userMapper.update(user, userUpdateWrapper);
System.out.println(result);
}
orderBy、orderByDesc、orderByAsc
排序：ORDER BY 字段, ...
例: orderBy(true, true, "id", "name")→order by id ASC,name ASC
排序：ORDER BY 字段, ... DESC
例: orderByDesc("id", "name")→order by id DESC, name DESC
排序：ORDER BY 字段, ... ASC
例: orderByAsc("id", "name")→order by id ASC,name ASC
@Test
public void queryWrapperNine() {
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.orderByDesc("id");
List<User> users = userMapper.selectList(queryWrapper);
users.forEach(System.out::println);
}
last
无视优化规则直接拼接到 sql 的最后
注意事项：
只能调用一次, 多次调用以最后一次为准有 sql 注入的风险, 请谨慎使用
例: last("limit 1")
@Test
public void queryWrapperTen() {
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.last("limit 1");
List<User> users = userMapper.selectList(queryWrapper);
users.forEach(System.out::println);
}
指定要查询的列
@Test
public void queryWrapperEleven() {
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.select("id", "name", "age");
List<User> users = userMapper.selectList(queryWrapper);
users.forEach(System.out::println);
}
set、setSql
SQL SET 字段
例: set("name", "老李头")
例: set("name", "")→数据库字段值变为空字符串
例: set("name", null)→据库字段值变为null
设置 SET 部分 SQL
例: setSql("name = '老李头'")
@Test
public void queryWrapperTwelve() {
// 修改值
User user = new User();
user.setAge(10);
// 修改条件
UpdateWrapper<User> userUpdateWrapper = new UpdateWrapper<>();
userUpdateWrapper
.like("name", "A")
// 除了可以查询还可以使用set设置修改的字段
.set("name", "BNTang")
// 可以有子查询
.setSql(" email = '303158131@qq.com'");
int result = userMapper.update(user, userUpdateWrapper);
System.out.println(result);
}
以上为个人经验，希望能给大家一个参考，也希望大家多多支持编程网。
