MyBatisPlus-QueryWrapper多条件查询及修改方式

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猪先飞。