MyBatisPlus（三）条件构造器

这里主要用到QueryWrapper和UpdateWrapper两个类，用于生成sql的where条件。

UpdateWrapper

根据 whereEntity 条件，删除记录

删除年龄为10岁的用户

@Test
public void testDelete() {
   
    int result = userMapper.delete(new UpdateWrapper<User>().eq("age", 10));
    System.out.println(result);
}

执行日志：

JDBC Connection [HikariProxyConnection@161938368 wrapping com.mysql.cj.jdbc.ConnectionImpl@c1fa7d4] will not be managed by Spring
==>  Preparing: DELETE FROM user WHERE (age = ?)
==> Parameters: 10(Integer)
<==    Updates: 1
Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@7b7b3edb]
1

更新 whereEntity 条件，更新记录

修改小于20岁用户的邮箱

@Test
public void testUpdate() {
   
    User user = new User();
    user.setEmail("mm@163.com");
    int result = userMapper.update(user, new UpdateWrapper<User>().le("age", 20));
    System.out.println(result);
}

执行结果：

JDBC Connection [HikariProxyConnection@203401172 wrapping com.mysql.cj.jdbc.ConnectionImpl@7a93b263] will not be managed by Spring
==>  Preparing: UPDATE user SET email=? WHERE (age <= ?)
==> Parameters: mm@163.com(String), 20(Integer)
<==    Updates: 3
Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@1dbb650b]
3

QueryWrapper

根据 whereEntity 条件，查询一条记录

查询id为2的用户

@Test
public void testSelectOne() {
   
    User user = userMapper.selectOne(new QueryWrapper<User>().eq("id", 2L));
    System.out.println(user);
}

执行日志：

JDBC Connection [HikariProxyConnection@1689723487 wrapping com.mysql.cj.jdbc.ConnectionImpl@33db72bd] will not be managed by Spring
==>  Preparing: SELECT id,name,age,email FROM user WHERE (id = ?)
==> Parameters: 2(Long)
<==    Columns: id, name, age, email
<==        Row: 2, Jack, 20, mm@163.com
<==      Total: 1
Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@15cea7b0]
User{id=2, name='Jack', age=20, email='mm@163.com'}

根据 whereEntity 条件，查询记录数量

查询年龄在20-30之前用户数量

@Test
public void testSelectCount() {
   
    Integer count = userMapper.selectCount(new QueryWrapper<User>().between("age", 20, 30));
    System.out.println(count);
}

执行日志：

JDBC Connection [HikariProxyConnection@859193874 wrapping com.mysql.cj.jdbc.ConnectionImpl@2216effc] will not be managed by Spring
==>  Preparing: SELECT COUNT( 1 ) FROM user WHERE (age BETWEEN ? AND ?)
==> Parameters: 20(Integer), 30(Integer)
<==    Columns: COUNT( 1 )
<==        Row: 3
<==      Total: 1
Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@6b474074]
3

更多条件构造器（来自官网）

#allEq

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)

个别参数说明:

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

• 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'

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)

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 null2IsNull : 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'

#eq

eq(R column, Object val)
eq(boolean condition, R column, Object val)

• 等于 =
• 例: eq("name", "老王")--->name = '老王'

#ne

ne(R column, Object val)
ne(boolean condition, R column, Object val)

• 不等于 <>
• 例: ne("name", "老王")--->name <> '老王'

#gt

gt(R column, Object val)
gt(boolean condition, R column, Object val)

• 大于 >
• 例: gt("age", 18)--->age > 18

#ge

ge(R column, Object val)
ge(boolean condition, R column, Object val)

• 大于等于 >=
• 例: ge("age", 18)--->age >= 18

#lt

lt(R column, Object val)
lt(boolean condition, R column, Object val)

• 小于 <
• 例: lt("age", 18)--->age < 18

#le

le(R column, Object val)
le(boolean condition, R column, Object val)

• 小于等于 <=
• 例: le("age", 18)--->age <= 18

#between

between(R column, Object val1, Object val2)
between(boolean condition, R column, Object val1, Object val2)

• BETWEEN 值1 AND 值2
• 例: between("age", 18, 30)--->age between 18 and 30

#notBetween

notBetween(R column, Object val1, Object val2)
notBetween(boolean condition, R column, Object val1, Object val2)

• NOT BETWEEN 值1 AND 值2
• 例: notBetween("age", 18, 30)--->age not between 18 and 30

#like

like(R column, Object val)
like(boolean condition, R column, Object val)

• LIKE '%值%'
• 例: like("name", "王")--->name like '%王%'

#notLike

notLike(R column, Object val)
notLike(boolean condition, R column, Object val)

• NOT LIKE '%值%'
• 例: notLike("name", "王")--->name not like '%王%'

#likeLeft

likeLeft(R column, Object val)
likeLeft(boolean condition, R column, Object val)

• LIKE '%值'
• 例: likeLeft("name", "王")--->name like '%王'

#likeRight

likeRight(R column, Object val)
likeRight(boolean condition, R column, Object val)

• LIKE '值%'
• 例: likeRight("name", "王")--->name like '王%'

#isNull

isNull(R column)
isNull(boolean condition, R column)

• 字段 IS NULL
• 例: isNull("name")--->name is null

#isNotNull

isNotNull(R column)
isNotNull(boolean condition, R column)

• 字段 IS NOT NULL
• 例: isNotNull("name")--->name is not null

#in

in(R column, Collection<?> value)
in(boolean condition, R column, Collection<?> value)

• 字段 IN (value.get(0), value.get(1), ...)
• 例: in("age",{1,2,3})--->age in (1,2,3)

in(R column, Object... values)
in(boolean condition, R column, Object... values)

• 字段 IN (v0, v1, ...)
• 例: in("age", 1, 2, 3)--->age in (1,2,3)

#notIn

notIn(R column, Collection<?> value)
notIn(boolean condition, R column, Collection<?> value)

• 字段 NOT IN (value.get(0), value.get(1), ...)
• 例: notIn("age",{1,2,3})--->age not in (1,2,3)

notIn(R column, Object... values)
notIn(boolean condition, R column, Object... values)

• 字段 NOT IN (v0, v1, ...)
• 例: notIn("age", 1, 2, 3)--->age not in (1,2,3)

#inSql

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

• 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)

#notInSql

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

• 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)

#groupBy

groupBy(R... columns)
groupBy(boolean condition, R... columns)

• 分组：GROUP BY 字段, ...
• 例: groupBy("id", "name")--->group by id,name

#orderByAsc

orderByAsc(R... columns)
orderByAsc(boolean condition, R... columns)

• 排序：ORDER BY 字段, ... ASC
• 例: orderByAsc("id", "name")--->order by id ASC,name ASC

#orderByDesc

orderByDesc(R... columns)
orderByDesc(boolean condition, R... columns)

• 排序：ORDER BY 字段, ... DESC
• 例: orderByDesc("id", "name")--->order by id DESC,name DESC

#orderBy

排序：ORDER BY 字段, ...

• 例: orderBy(true, true, "id", "name")--->order by id ASC,name ASC

#having

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

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

#func

func(Consumer<Children> consumer)
func(boolean condition, Consumer<Children> consumer)

• func 方法(主要方便在出现if...else下调用不同方法能不断链)
• 例: func(i -> if(true) {i.eq("id", 1)} else {i.ne("id", 1)})

#or

or()
or(boolean condition)

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

• OR 嵌套
• 例: or(i -> i.eq("name", "李白").ne("status", "活着"))--->or (name = '李白' and status <> '活着')

#and

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

• AND 嵌套
• 例: and(i -> i.eq("name", "李白").ne("status", "活着"))--->and (name = '李白' and status <> '活着')

#nested

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

• 正常嵌套 不带 AND 或者 OR
• 例: nested(i -> i.eq("name", "李白").ne("status", "活着"))--->(name = '李白' and status <> '活着')

#apply

pply(String applySql, Object... params)
apply(boolean condition, String applySql, Object... params)

• 拼接 sql

注意事项:

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!

• 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'")

#last

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

• 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")

#exists

exists(String existsSql)
exists(boolean condition, String existsSql)

• 拼接 EXISTS ( sql语句 )
• 例: exists("select id from table where age = 1")--->exists (select id from table where age = 1)

#notExists

notExists(String notExistsSql)
notExists(boolean condition, String notExistsSql)

• 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)

上一篇：SpringBoot 全家桶 | MyBatisPlus（二）提供的CRUD功能
下一篇：SpringBoot 全家桶 | MyBatisPlus（四）分页与排序