Mybatis Plus 系列3.2 —— Mapper CRUD之条件构造器

mybatis plus

发布日期: 2021-02-13

文章字数: 4.1k

阅读时长: 21 分

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接着 Mybatis Plus 系列3.1 —— Mapper CRUD之查询我们这章主要讲一下条件构造器。

关于条件构造器，还是先贴一下官网的说明：

以下出现的第一个入参boolean condition表示该条件是否加入最后生成的sql中，例如：query.like(StringUtils.isNotBlank(name), Entity::getName, name) .eq(age!=null && age >= 0, Entity::getAge, age)
以下代码块内的多个方法均为从上往下补全个别boolean类型的入参,默认为true
以下出现的泛型Param均为Wrapper的子类实例(均具有AbstractWrapper的所有方法)
以下方法在入参中出现的R为泛型,在普通wrapper中是String,在LambdaWrapper中是函数(例:Entity::getId,Entity为实体类,getId为字段id的getMethod)
以下方法入参中的R column均表示数据库字段,当R具体类型为String时则为数据库字段名(字段名是数据库关键字的自己用转义符包裹!)!而不是实体类数据字段名!!!,另当R具体类型为SFunction时项目runtime不支持eclipse自家的编译器!!!
以下举例均为使用普通wrapper,入参为Map和List的均以json形式表现!
使用中如果入参的Map或者List为空,则不会加入最后生成的sql中!!!

还是先看一下Wrapper的类继承关系：

上一章就说过，我是推荐使用 Lambda 表达式的方式构建Wrapper的，所以我们主要使用：LambdaQueryWrapper和LambdaUpdateWrapper来做示例，首先看一下类图：

gaitubao_LambdaQueryWrapper

我们按照官网的顺序介绍一条件构造器。

一. AbstractWrapper

QueryWrapper(LambdaQueryWrapper) 和 UpdateWrapper(LambdaUpdateWrapper) 的父类
用于生成 sql 的 where 条件, entity 属性也用于生成 sql 的 where 条件
注意: entity 生成的 where 条件与使用各个 api 生成的 where 条件没有任何关联行

1. eq

等于

eq(R column, Object val)   // 底层调的就是 eq(true, column, val);
eq(boolean condition, R column, Object val)

示例：

@Test
@DisplayName("条件构造器1-eq")
public void eqTest1() {
  LambdaQueryWrapper<User> eq = Wrappers.<User>lambdaQuery()
    .eq(User::getSex, "MAIL")
    .eq(User::getIsDelete, false);

  List<User> users = userMapper.selectList(eq);
  Assertions.assertFalse(users.isEmpty());
}

结果：

==>  Preparing: SELECT id,name,age,email,sex,is_delete,create_time,update_time FROM user WHERE (sex = ? AND is_delete = ?)
==> Parameters: MAIL(String), false(Boolean)
<==    Columns: id, name, age, email, sex, is_delete, create_time, update_time
<==        Row: 1, Jone, 18, test1@baomidou.com, MAIL, 0, 2021-02-12 22:43:00, 2021-02-12 22:43:00
<==        Row: 2, Jack, 20, test2@baomidou.com, MAIL, 0, 2021-02-12 22:43:00, 2021-02-12 22:43:00
<==        Row: 3, Tom, 28, test3@baomidou.com, MAIL, 0, 2021-02-12 22:43:00, 2021-02-12 22:43:00
<==      Total: 3

这里重点介绍一下重载方法eq(boolean condition, R column, Object val)

这里面有一个condition（执行条件）参数，用来控制当前条件是否会加到最终的SQL中去。举个例子：有一个用户查询列表页面，查询条件有”姓名“，”性别“等，如果某个条件没输入，则忽略该条件。这种场景大家应该经非常熟悉，之前我们可以使用mybatis的动态SQL来实现。这里我们就可以利用condition条件，比较优雅的实现这个功能。

@Test
@DisplayName("条件构造器2-eq")
public void eqTest2() {
  // 模拟输入的查询条件
  String name = "jack";
  String sex = null;

  LambdaQueryWrapper<User> eq = Wrappers.<User>lambdaQuery()
    .eq(StringUtils.hasLength(name), User::getName, name) // name 不为空时，使用该条件
    .eq(StringUtils.hasLength(sex), User::getSex, sex) // sex 不为空时，使用该条件
    .eq(User::getIsDelete, false);

  List<User> users = userMapper.selectList(eq);
  Assertions.assertFalse(users.isEmpty());
}

结果，可见where条件并没有sex相关的条件了:

==>  Preparing: SELECT id,name,age,email,sex,is_delete,create_time,update_time FROM user WHERE (name = ? AND is_delete = ?)
==> Parameters: jack(String), false(Boolean)
<==    Columns: id, name, age, email, sex, is_delete, create_time, update_time
<==        Row: 2, Jack, 20, test2@baomidou.com, MAIL, 0, 2021-02-12 22:43:00, 2021-02-12 22:43:00
<==      Total: 1

对比一下不使用condition条件的情况：

@Test
@DisplayName("条件构造器2-eq")
public void eqTest2() {
  // 模拟输入的查询条件
  String name = "jack";
  String sex = null;

  LambdaQueryWrapper<User> eq = Wrappers.<User>lambdaQuery()
  .eq(User::getName, name)
  .eq(User::getSex, sex)
  .eq(User::getIsDelete, false);

  List<User> users = userMapper.selectList(eq);
  Assertions.assertTrue(users.isEmpty());
}

结果：

==>  Preparing: SELECT id,name,age,email,sex,is_delete,create_time,update_time FROM user WHERE (name = ? AND sex = ? AND is_delete = ?)
==> Parameters: jack(String), null, false(Boolean)
<==      Total: 0

说明：

不仅仅eq条件有关于condition的重载方法，其它的也有，使用方式也一样，后面就不再逐个演示了！

2. ne

不等于

ne(R column, Object val) // ne(true, column, val);
ne(boolean condition, R column, Object val)

示例：

@Test
@DisplayName("条件构造器-ne")
public void neTest() {
  LambdaQueryWrapper<User> eq = Wrappers.<User>lambdaQuery()
    .ne(User::getSex, "MAIL")
    .eq(User::getIsDelete, false);

  List<User> users = userMapper.selectList(eq);
  Assertions.assertFalse(users.isEmpty());
}

结果：

==>  Preparing: SELECT id,name,age,email,sex,is_delete,create_time,update_time FROM user WHERE (sex <> ? AND is_delete = ?)
==> Parameters: MAIL(String), false(Boolean)
<==    Columns: id, name, age, email, sex, is_delete, create_time, update_time
<==        Row: 4, Sandy, 21, test4@baomidou.com, FEMALE, 0, 2021-02-12 22:43:00, 2021-02-12 22:43:00
<==        Row: 5, Billie, 24, test5@baomidou.com, FEMALE, 0, 2021-02-12 22:43:00, 2021-02-12 22:43:00
<==      Total: 2

3. allEq

全部eq(或个别isNull)

// params : key为数据库字段名, value为字段值
// null2IsNull : 为true则在map的value为null时调用 isNull 方法,为false时则忽略value为null的
// filter : 过滤函数,是否允许字段传入比对条件中

allEq(Map<R, V> params) // 底层调用 allEq(params, true);
allEq(Map<R, V> params, boolean null2IsNull) // 底层调用 allEq(true, params, null2IsNull);
allEq(boolean condition, Map<R, V> params, boolean null2IsNull)  
  
allEq(BiPredicate<R, V> filter, Map<R, V> params) // 底层调用 allEq(filter, params, true)
allEq(BiPredicate<R, V> filter, Map<R, V> params, boolean null2IsNull) // 底层调用 allEq(true, filter, params, null2IsNull)
allEq(boolean condition, BiPredicate<R, V> filter, Map<R, V> params, boolean null2IsNull)

示例1：

@Test
@DisplayName("条件构造器1-allEq")
public void allEqTest1() {
  Map<SFunction<User, ?>, Object> param = new HashMap<>();
  param.put(User::getSex, "MAIL");
  param.put(User::getIsDelete, false);

  // param 为 null 或者 empty 则查询全部
  LambdaQueryWrapper<User> eq = Wrappers.<User>lambdaQuery().allEq(param);

  List<User> users = userMapper.selectList(eq);
  Assertions.assertFalse(users.isEmpty());
}

结果：

==>  Preparing: SELECT id,name,age,email,sex,is_delete,create_time,update_time FROM user WHERE (is_delete = ? AND sex = ?)
==> Parameters: false(Boolean), MAIL(String)
<==    Columns: id, name, age, email, sex, is_delete, create_time, update_time
<==        Row: 1, Jone, 18, test1@baomidou.com, MAIL, 0, 2021-02-12 22:43:00, 2021-02-12 22:43:00
<==        Row: 2, Jack, 20, test2@baomidou.com, MAIL, 0, 2021-02-12 22:43:00, 2021-02-12 22:43:00
<==        Row: 3, Tom, 28, test3@baomidou.com, MAIL, 0, 2021-02-12 22:43:00, 2021-02-12 22:43:00
<==      Total: 3

示例2：

@Test
@DisplayName("条件构造器2-allEq")
public void allEqTest2() {
  Map<SFunction<User, ?>, Object> param = new HashMap<>();
  param.put(User::getSex, "MAIL");
  param.put(User::getIsDelete, null);

  LambdaQueryWrapper<User> eq = Wrappers.<User>lambdaQuery()
    .allEq(param, false); // 默认null2IsNull 为 true， 此时查询调价会忽略value为null的key

  List<User> users = userMapper.selectList(eq);
  Assertions.assertFalse(users.isEmpty());
}

结果：

==>  Preparing: SELECT id,name,age,email,sex,is_delete,create_time,update_time FROM user WHERE (sex = ?)
==> Parameters: MAIL(String)
<==    Columns: id, name, age, email, sex, is_delete, create_time, update_time
<==        Row: 1, Jone, 18, test1@baomidou.com, MAIL, 0, 2021-02-12 22:43:00, 2021-02-12 22:43:00
<==        Row: 2, Jack, 20, test2@baomidou.com, MAIL, 0, 2021-02-12 22:43:00, 2021-02-12 22:43:00
<==        Row: 3, Tom, 28, test3@baomidou.com, MAIL, 0, 2021-02-12 22:43:00, 2021-02-12 22:43:00
<==      Total: 3

示例3：

@Test
@DisplayName("条件构造器3-allEq")
public void allEqTest3() {
  
  SFunction<User, ?> sex = User::getSex;
  Map<SFunction<User, ?>, Object> param = new HashMap<>();
  param.put(sex, "MAIL");
  param.put(User::getIsDelete, false);

  LambdaQueryWrapper<User> eq = Wrappers.<User>lambdaQuery()
    .allEq((k, v) -> {
      // 过滤函数,是否允许字段传入比对条件中
      log.info("k = {}, v = {}", k, v);
      return sex.equals(k); // 只需要 sex 条件, 如果过滤出来为空（始终返回false），那么则全量查询
    }, param); // 默认null2IsNull 为 true， 此时查询调价会忽略value为null的key
  List<User> users = userMapper.selectList(eq);
  Assertions.assertFalse(users.isEmpty());
}

2021-02-13 12:28:16.153  INFO 40236 --- [    Test worker] c.j.m.demo.demo.UserWrapperTest          : k = cn.justmr.mybatisplus.demo.demo.UserWrapperTest$$Lambda$829/1464585291@6e247c30, v = MAIL
2021-02-13 12:28:16.158  INFO 40236 --- [    Test worker] c.j.m.demo.demo.UserWrapperTest          : k = cn.justmr.mybatisplus.demo.demo.UserWrapperTest$$Lambda$830/567167554@3f9bd04, v = false
...
==>  Preparing: SELECT id,name,age,email,sex,is_delete,create_time,update_time FROM user WHERE (sex = ?)
==> Parameters: MAIL(String)
<==    Columns: id, name, age, email, sex, is_delete, create_time, update_time
<==        Row: 1, Jone, 18, test1@baomidou.com, MAIL, 0, 2021-02-12 22:43:00, 2021-02-12 22:43:00
<==        Row: 2, Jack, 20, test2@baomidou.com, MAIL, 0, 2021-02-12 22:43:00, 2021-02-12 22:43:00
<==        Row: 3, Tom, 28, test3@baomidou.com, MAIL, 0, 2021-02-12 22:43:00, 2021-02-12 22:43:00
<==      Total: 3

4. gt

大于
ge(R column, Object val)
ge(boolean condition, R column, Object val)
示例：.gt(User::getAge, 18) ---> age > 18

5. ge

大于等于
ge(R column, Object val)
ge(boolean condition, R column, Object val)
示例：.ge(User::getAge, 18) ---> age >= 18

6. lt

小于
lt(R column, Object val)
lt(boolean condition, R column, Object val)
示例：.lt(User::getAge, 18) ---> age < 18

7. le

小于等于
le(R column, Object val)
le(boolean condition, R column, Object val)
示例：.le(User::getAge, 18) ---> age <= 18

8. between

BETWEEN 值1 AND 值2
between(R column, Object val1, Object val2)
between(boolean condition, R column, Object val1, Object val2)
示例：.between(User::getAge, 18, 20) ---> age BETWEEN 18 AND 20

9. notBetween

NOT BETWEEN 值1 AND 值2
notBetween(R column, Object val1, Object val2)
notBetween(boolean condition, R column, Object val1, Object val2)
示例：.notBetween(User::getAge, 18, 20) ---> age NOT BETWEEN 18 AND 20

10. like

模糊查询 LIKE '%值%'
like(R column, Object val)
like(boolean condition, R column, Object val)
示例：.like(User::getName, "J") ---> name LIKE '%J%'

注意：不需要自己拼接’%’了

11. notLike

NOT LIKE ‘%值%’
notLike(R column, Object val)
notLike(boolean condition, R column, Object val)
示例：.notLike(User::getName, "J") ---> name NOT LIKE '%J%'

12. likeLeft

LIKE ‘%值’
likeLeft(R column, Object val)
likeLeft(boolean condition, R column, Object val)
示例：.likeLeft(User::getName, "J") ---> name LIKE '%J'

13. likeRight

LIKE ‘值%’
likeRight(R column, Object val)
likeRight(boolean condition, R column, Object val)
示例：.likeRight(User::getName, "J") ---> name LIKE 'J%'

14. isNull

字段 IS NULL
isNull(R column)
isNull(boolean condition, R column)
示例：.isNull(User::getName) ---> name IS NULL

15. isNotNull

字段 IS NOT NULL
isNotNull(R column)
isNotNull(boolean condition, R column)
示例：.isNotNull(User::getName) ---> name IS NOT NULL

16. in

字段 IN (value.get(0), value.get(1), …)
in(R column, Collection<?> value)
in(boolean condition, R column, Collection<?> value)
示例：.in(User::getId, Lists.list(1L, 2L)) ---> id IN (1, 2)

注意：

value不能为null，会报错
value不能为空，会报错，例如

SELECT id,name,age,email,sex,is_delete,create_time,update_time FROM user WHERE id IN ();这个sql执行报错

17. notIn

字段 NOT IN (value.get(0), value.get(1), …)
notIn(R column, Collection<?> value)
notIn(boolean condition, R column, Collection<?> value)
示例：.notIn(User::getId, Lists.list(1L, 2L)) ---> id NOT IN (1, 2)

18. inSql

字段 IN ( sql语句 )

inSql(R column, String inValue)
inSql(boolean condition, R column, String inValue)

例: .inSql(User::getId, "1, 2") --- > id IN (1, 2) // 会有sql注入风险
例: inSql(User::getId, "select id from table where id < 3") ---> id IN (select id from user where id < 3)

19. notInSql

字段 NOT IN ( sql语句 )

notInSql(R column, String inValue)
notInSql(boolean condition, R column, String inValue)

20. groupBy

分组：GROUP BY 字段, …
groupBy(R... columns)
groupBy(boolean condition, R... columns)
示例：.groupBy(User::getSex) ---> GROUP BY sex

21. orderByAsc

排序：ORDER BY 字段, … ASC
orderByAsc(R... columns)
orderByAsc(boolean condition, R... columns)
示例:.orderByAsc(orderByAsc(User::getCreateTime, User::getId)) ---> ORDER BY create_time ASC, id ASC

22. orderByDesc

排序：ORDER BY 字段, … DESC
orderByDesc(R... columns)
orderByDesc(boolean condition, R... columns)
示例:.orderByDesc(orderByAsc(User::getCreateTime, User::getId)) ---> ORDER BY create_time DESC, id DESC

23. orderBy

排序：ORDER BY 字段, …
orderBy(boolean condition, boolean isAsc, R... columns)
示例：.orderBy(true, true, User::getCreateTime, User::getId) ---> ORDER BY create_time ASC, id ASC

24. having

HAVING ( sql语句 )

having(String sqlHaving, Object... params)
having(boolean condition, String sqlHaving, Object... params)

例: having("sum(age) > 10") ---> having sum(age) > 10
例: having("sum(age) > {0}", 11) ---> having sum(age) > 11

25. func

主要方便在出现if…else下调用不同方法能不断链
func(Consumer<Children> consumer)
func(boolean condition, Consumer<Children> consumer)

示例1：

@Test
@DisplayName("条件构造器1-apply")
public void applyTest1() {
  List<Long> ids = Lists.list(1L);
  LambdaQueryWrapper<User> eq = Wrappers.<User>lambdaQuery()
    .func(item -> {
      if (CollectionUtils.isEmpty(ids)) {
        item.apply("1 != 1");
      } else {
        item.in(User::getId, ids);
      }
    })
    .eq(User::getIsDelete, false)
    .orderByAsc(User::getCreateTime);

  List<User> users = userMapper.selectList(eq);
  Assertions.assertFalse(users.isEmpty());
}

结果：

==>  Preparing: SELECT id,name,age,email,sex,is_delete,create_time,update_time FROM user WHERE (id IN (?) AND is_delete = ?) ORDER BY create_time ASC
==> Parameters: 1(Long), false(Boolean)
<==    Columns: id, name, age, email, sex, is_delete, create_time, update_time
<==        Row: 1, Jone, 18, test1@baomidou.com, MAIL, 0, 2021-02-12 22:43:00, 2021-02-12 22:43:00
<==      Total: 1

示例2，对比一下示例1：

@Test
@DisplayName("条件构造器2-apply")
public void applyTest2() {
  List<Long> ids = Lists.list();
  LambdaQueryWrapper<User> eq = Wrappers.<User>lambdaQuery()
    .func(item -> {
      if (CollectionUtils.isEmpty(ids)) {
        item.apply("1 != 1");
      } else {
        item.in(User::getId, ids);
      }
    })
    .eq(User::getIsDelete, false)
    .orderByAsc(User::getCreateTime);

  List<User> users = userMapper.selectList(eq);
  Assertions.assertTrue(users.isEmpty());
}

结果：

==>  Preparing: SELECT id,name,age,email,sex,is_delete,create_time,update_time FROM user WHERE (1 != 1 AND is_delete = ?) ORDER BY create_time ASC
==> Parameters: false(Boolean)
<==      Total: 0

26. or

拼接 OR

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)
or()
or(boolean condition)
示例：

// 1. WHERE id = 1 OR name = 'Jack' AND is_delete = false
  .eq(User::getId, 1L)
  .or()
  .eq(User::getName, "Jack")
  .eq(User::getIsDelete, false)

// 2. WHERE id = 1 AND name = 'Jack' AND is_delete = false
  .eq(User::getId, 1L)
  .or(false)
  .eq(User::getName, "Jack")
  .eq(User::getIsDelete, false);

or嵌套

or(Consumer<Param> consumer)
or(boolean condition, Consumer<Param> consumer)

示例：

// 1. WHERE (id = ? OR (name = ? AND email = ?) AND is_delete = ?)
.eq(User::getId, 1L)
.or(i -> i.eq(User::getName, "JACK").eq(User::getEmail, "22@qq.com"))
.eq(User::getIsDelete, false);

// 2. WHERE (id = ? AND is_delete = ?)
.eq(User::getId, 1L)
.or(false, i -> i.eq(User::getName, "JACK").eq(User::getEmail, "22@qq.com"))
.eq(User::getIsDelete, false);

27. and

AND 嵌套

and(Consumer<Param> consumer)
and(boolean condition, Consumer<Param> consumer)

示例:

// WHERE (name = ? AND (age = ? OR age = ?) AND is_delete = ?)
.eq(User::getName, "Jack")
.and(i -> i.eq(User::getAge, 18).or().eq(User::getAge, 21))
.eq(User::getIsDelete, false);

28. nested

正常嵌套不带 AND 或者 OR
>nested(Consumer<Param> consumer)
>nested(boolean condition, Consumer<Param> consumer)
示例：

// WHERE (name = ? AND (age = ? OR age = ?) AND is_delete = ?)
.eq(User::getName, "Jack")
.nested(i -> i.eq(User::getAge, 18).or().eq(User::getAge, 21))
.eq(User::getIsDelete, false);

29. apply

拼接 sql

该方法可用于数据库函数动态入参的params对应前面applySql内部的{index}部分.这样是不会有sql注入风险的,反之会有!
apply(String applySql, Object... params)
apply(boolean condition, String applySql, Object... params)
示例：

例: apply("id = 1")—>id = 1
例: apply("date_format(dateColumn,'%Y-%m-%d') = '2008-08-08'")—>date_format(dateColumn,'%Y-%m-%d') = '2008-08-08'")
例: apply("date_format(dateColumn,'%Y-%m-%d') = {0}", "2008-08-08")—>date_format(dateColumn,'%Y-%m-%d') = '2008-08-08'")

30. last

无视优化规则直接拼接到 sql 的最后

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
last(String lastSql)
last(boolean condition, String lastSql)

使用的较多的就是last("limit 1")

@Test
@DisplayName("条件构造器-last")
public void lastTest() {
  LambdaQueryWrapper<User> eq = Wrappers.<User>lambdaQuery()
    .gt(User::getAge, 18)
    .eq(User::getIsDelete, false)
    .orderByDesc(User::getAge)
    .last("limit 1");

  User user = userMapper.selectOne(eq);
  Assertions.assertTrue(user != null);
}

结果:

==>  Preparing: SELECT id,name,age,email,sex,is_delete,create_time,update_time FROM user WHERE (age > ? AND is_delete = ?) ORDER BY age DESC limit 1
==> Parameters: 18(Integer), false(Boolean)
<==    Columns: id, name, age, email, sex, is_delete, create_time, update_time
<==        Row: 3, Tom, 28, test3@baomidou.com, MAIL, 0, 2021-02-12 22:43:00, 2021-02-12 22:43:00
<==      Total: 1

31. exists

拼接 EXISTS ( sql语句 )
exists(String existsSql)
exists(boolean condition, String existsSql)
示例: exists("select id from table where age = 1") ---> exists (select id from table where age = 1)

32. notExists

拼接 NOT EXISTS ( sql语句 )
notExists(String notExistsSql)
notExists(boolean condition, String notExistsSql)
示例: notExists("select id from table where age = 1") ---> not exists (select id from table where age = 1)

二. QueryWrapper

继承自 AbstractWrapper ,自身的内部属性 entity 也用于生成 where 条件
及 LambdaQueryWrapper, 可以通过 new QueryWrapper().lambda() 方法获取

1. select

设置查询字段

select(String... sqlSelect)
select(Predicate<TableFieldInfo> predicate)
select(Class<T> entityClass, Predicate<TableFieldInfo> predicate)

以上方法分为两类.
第二类方法为:过滤查询字段(主键除外),入参不包含 class 的调用前需要wrapper内的entity属性有值! 这两类方法重复调用以最后一次为准

示例：

// 1. SELECT id,name FROM user WHERE (is_delete = ?)
QueryWrapper<User> eq = Wrappers.<User>query()
  .select("id", "name")
  .eq("is_delete", false);

List<User> users = userMapper.selectList(eq);

// 2. ELECT id,name FROM user WHERE (is_delete = ?)
QueryWrapper<User> eq = Wrappers.<User>query()
  .setEntityClass(User.class) // 必要
  .select(i -> i.getProperty().equals("name"))
  .eq("is_delete", false);

List<User> users = userMapper.selectList(eq);

// 3. SELECT id,name FROM user WHERE (is_delete = ?)
QueryWrapper<User> eq = Wrappers.<User>query()
  .select(User.class, i -> i.getProperty().equals("name"))
  .eq("is_delete", false);

List<User> users = userMapper.selectList(eq);

2. lambda

获取LambdaQueryWrapper

示例：

LambdaQueryWrapper<User> eq = Wrappers.<User>query().lambda()
                .select(User::getId, User::getName)
                .eq(User::getIsDelete, false);

三. UpdateWrapper

继承自 AbstractWrapper ,自身的内部属性 entity 也用于生成 where 条件
及 LambdaUpdateWrapper, 可以通过 new UpdateWrapper().lambda() 方法获取!

1. set

QL SET 字段
set(String column, Object val)
set(boolean condition, String column, Object val)
示例: set("name", "老李头")

示例: set("name", "")—>数据库字段值变为空字符串

示例:set("name", null)—>数据库字段值变为null

2. setSql

设置 SET 部分 SQL
setSql(String sql)
示例: setSql("name = '老李头'")

3. lambda

获取LambdaUpdateWrapper

示例：

LambdaUpdateWrapper<User> eq = Wrappers.<User>update().lambda()
                .set(User::getEmail, "33@qq.com")
                .eq(User::getId, 1L);

shiv

http://wvht2y.coding-pages.com/2021/02/13/mybatis-plus-3-2-mapper-crud-zhi-tiao-jian-gou-zao-qi/

本博客所有文章除特別声明外，均采用 CC BY 4.0 许可协议。转载请注明来源 shiv !

spring boot mybatis plus mybatis

Mybatis Plus 系列3.3 —— Mapper CRUD之分页查询

2021-02-13 mybatis plus

spring boot mybatis plus mybatis

Mybatis Plus 系列3.1 —— Mapper CRUD之查询

2021-02-13 mybatis plus

spring boot mybatis plus mybatis

Mybatis Plus 系列3.2 —— Mapper CRUD之条件构造器

一. AbstractWrapper

1. eq

2. ne

3. allEq

4. gt

5. ge

6. lt

7. le

8. between

9. notBetween

10. like

11. notLike

12. likeLeft

13. likeRight

14. isNull

15. isNotNull

16. in

17. notIn

18. inSql

19. notInSql

20. groupBy

21. orderByAsc

22. orderByDesc

23. orderBy

24. having

25. func

26. or

27. and

28. nested

29. apply

30. last

31. exists

32. notExists

二. QueryWrapper

1. select

2. lambda

三. UpdateWrapper

1. set

2. setSql

3. lambda

你的赏识是我前进的动力