MyBatisPlus-QueryWrapper多条件查询以及修改

文章目录

  • MyBatisPlus-QueryWrapper多条件查询以及修改
    • gt、ge、lt、le、isNull、isNotNull
    • eq、ne
    • between、notBetween
    • allEq
    • like、notLike、likeLeft、likeRight
    • in、notIn、inSql、notinSql、exists、notExists
    • or、and
    • 嵌套 or、嵌套 and
    • orderBy、orderByDesc、orderByAsc
    • last
    • 指定要查询的列
    • set、setSql

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
@Testpublic 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'
@Testpublic 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
@Testpublic 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'
@Testpublic 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%'
@Testpublic 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)
@Testpublic 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')
@Testpublic 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

@Testpublic 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
@Testpublic 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")
@Testpublic 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

@Testpublic 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'")
@Testpublic 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);}