5.mybatis-plus-条件构造器

1.简介

Wrapper条件构造器，可以通过其构造复杂的SQL

Wrapper  条件构造抽象类
    -- AbstractWrapper 查询条件封装，用于生成 sql 中的 where 语句。
        -- QueryWrapper Entity 对象封装操作类，用于查询。
        -- UpdateWrapper Update 条件封装操作类，用于更新。
        -- AbstractLambdaWrapper 使用 Lambda 表达式封装 wrapper
            -- LambdaQueryWrapper 使用 Lambda 语法封装条件，用于查询。
            -- LambdaUpdateWrapper 使用 Lambda 语法封装条件，用于更新。

2.条件构造器-方法

2.1-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.contains("a"), {id:1,name:"老王",age:null})—>name = '老王' and age is null
• 例2: allEq((k,v) -> k.contains("a"), {id:1,name:"老王",age:null}, false)—>name = '老王'

2.2-eq

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

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

2.3-ne

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

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

2.4-gt

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

• 大于 >
• 例: gt("age", 18)—>age > 18

2.5-ge

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

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

2.6-lt

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

• 小于 <
• 例: lt("age", 18)—>age < 18

2.7-le

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

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

2.8- 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

2.9-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

2.10-like

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

• LIKE ‘%值%’
• 例: like("name", "王")—>name like '%王%'

2.11-notLike

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

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

2.12-likeLeft

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

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

2.13-likeRight

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

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

2.14-notLikeLeft

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

• NOT LIKE ‘%值’
• 例: notLikeLeft("name", "王")—>name not like '%王'

2.15-notLikeRight

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

• NOT LIKE ‘值%’
• 例: notLikeRight("name", "王")—>name not like '王%'

2.16-isNull

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

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

2.17-isNotNull

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

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

2.18-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)

2.19-notIn

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)

2.20-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)

2.21-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)

2.22-groupBy

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

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

2.23-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

2.24-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

2.25-orderBy

orderBy(boolean condition, boolean isAsc, R... columns)

• 排序：ORDER BY 字段, …
• 例: orderBy(true, true, "id", "name")—>order by id ASC,name ASC

2.26-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

2.27-having

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)})

2.28-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')

2.29-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')

2.30-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')

2.31-apply

apply(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'")

2.32-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")

2.33-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)

2.34-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)

3.QueryWrapper

说明:

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

select

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

    @Test
    public void QueryWrapper1(){
        //查询用户名包含`四`,年龄在22-30之间,邮箱不为null的用户
        QueryWrapper<User> queryWrapper = new QueryWrapper<>();
        queryWrapper
                .like("user_name","四")
                .between("age",22,30)
                .isNotNull("email");
        List<User> users = userMapper.selectList(queryWrapper);
        users.forEach(System.out::println);
    }

4.UpdateWrapper

说明:

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

set(String column, Object val)
set(boolean condition, String column, Object val)

• 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)—>数据库字段值变为null

2.setSql

setSql(String sql)

• 设置 SET 部分 SQL
• 例: setSql("name = '老李头'")

3.lambda

• 获取 LambdaWrapper
  在QueryWrapper中是获取LambdaQueryWrapper
  在UpdateWrapper中是获取LambdaUpdateWrapper