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
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'
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
public void queryWrapperThree() {
QueryWrapper<User> queryWrapper = new QueryWrapper<>();
queryWrapper.between("age", 20, 30);
Integer count = userMapper.selectCount(queryWrapper);
System.out.println(count);
}
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'
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%'
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)
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')
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
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
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")
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
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'")
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);
}
