MybatisPlus条件构造器WrapperMybatisPlus条件构造器

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文章目录

MybatisPlus条件构造器
- allEq
- 基本比较操作
- 模糊查询
- 排序
- 逻辑拼接
- select

MybatisPlus条件构造器

allEq

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allEq(Map< R, V> params)
allEq(Map< R, V> params, boolean null2IsNull)
allEq(boolean condition, Map< R, V> params, boolean null2IsNull)

全部eq或个别isNull

params
key:数据库字段名
value:字段值
null2IsNull:true则在map的value为null时调用isNull，为false则忽略为null的value

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allEq(BiPredicate< R, V> filter, Map< R, V> params)
allEq(BiPredicate< R, V> filter, Map< R, V> params, boolean null2IsNull)
allEq(boolean condition, BiPredicate< R, V> filter, Map< R, V> params, boolean
null2IsNull)

filter:过滤函数是否允许字段传入比对条件中

示例

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@Test
public void testWrapper(){
Map< String,Object> params=new HashMap< >();
params.put("age",30);
params.put("name","Peyton Hogg");
params.put("password",null);
QueryWrapper< User> wrapper=new QueryWrapper< >();
//SELECT id,user_name,password,name,age,email FROM tb_user WHERE (password IS NULL AND name = ? AND age = ?)
//wrapper.allEq(params);
//SELECT id,user_name,password,name,age,email FROM tb_user WHERE (name = ? AND age = ?)
//wrapper.allEq(params,false);
//SELECT id,user_name,password,name,age,email FROM tb_user WHERE (age = ?)
wrapper.allEq((k,v)->(k.equals("age")),params);
List< User> users = userMapper.selectList(wrapper);
for (User user : users) {
System.out.println(user);
}
}

基本比较操作

eq
- 等于 =
ne
- 不等于 < >
gt
- 大于 >
ge
- 大于等于 >=
lt
- 小于<
le
- 小于等于< =
between
- BETWEEN 值1 AND 值2
notBetween
- NOTBETWEEN 值1AND 值2
in
- 字段 IN (values)
notIn
- 字段NOT IN(values)

示例

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@Test
public void testWrapper(){
QueryWrapper< User> wrapper=new QueryWrapper< >();
//SELECT id,user_name,password,name,age,email FROM tb_user WHERE (age > ? AND id BETWEEN ? AND ?)
wrapper.gt("age",20).between("id",6L,9L);
List< User> users = userMapper.selectList(wrapper);
for (User user : users) {
System.out.println(user);
}
}

模糊查询

like
- LIKE ‘%值%’
notLike
- NOT LIKE ‘%值%’
likeLeft
- LIKE ‘%值’
likeRight
- LIKE ‘值%’

示例

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@Test
public void testWrapper(){
QueryWrapper< User> wrapper=new QueryWrapper< >();
//Preparing: SELECT id,user_name,password,name,age,email FROM tb_user WHERE (name LIKE ?)
//Parameters: %n(String)
wrapper.likeLeft("name","n");
List< User> users = userMapper.selectList(wrapper);
for (User user : users) {
System.out.println(user);
}
}

排序

orderBy
- ORDER BY 字段
orderByAsc 升序
- ORDER BY 字段 ASC
orderByDesc 降序
- ORDER BY 字段 DESC

示例

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@Test
public void testWrapper(){
QueryWrapper< User> wrapper=new QueryWrapper< >();
//SELECT id,user_name,password,name,age,email FROM tb_user ORDER BY age ASC
wrapper.orderByAsc("age");
List< User> users = userMapper.selectList(wrapper);
for (User user : users) {
System.out.println(user);
}
}

逻辑拼接

or
- 拼接OR
and
- AND嵌套

示例

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@Test
public void testWrapper(){
QueryWrapper< User> wrapper=new QueryWrapper< >();
//SELECT id,user_name,password,name,age,email FROM tb_user WHERE (age = ? OR age = ?)
wrapper.eq("age",19).or().eq("age",24);
List< User> users = userMapper.selectList(wrapper);
for (User user : users) {
System.out.println(user);
}
}

select

可用于指定要查询的字段

示例

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@Test
public void testWrapper(){
QueryWrapper< User> wrapper=new QueryWrapper< >();
//SELECT id,name,age FROM tb_user
wrapper.select("id","name","age");
List< User> users = userMapper.selectList(wrapper);
for (User user : users) {
System.out.println(user);
}
}