MyBatisPlus-QueryWrapper多条件查询以及修改

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 = '[email protected]'");

    int result = userMapper.update(user, userUpdateWrapper);
    System.out.println(result);
}