QueryWarpper的使用方法，MyBatics Plus的查询方法处理

程序员文章站 2022-03-12 22:05:30

目录#AbstractWrapper#allEq#eq#ne#gt#ge#lt#le#between#notBetween#like#notLike#likeLeft#likeRight#isNull#isNotNull#in#notIn#inSql#notInSql#groupBy#orderByAsc#orderByDesc#orderBy#havi......

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# AbstractWrapper

MyBatics Plus官网

https://mp.baomidou.com/guide/#%E7%89%B9%E6%80%A7

# AbstractWrapper

说明:

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为

# 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

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

# 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

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'")

# 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)

# 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)

设置查询字段

说明:

以上方分法为两类.
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

例: select("id", "name", "age")
例: select(i -> i.getProperty().startsWith("test"))

# 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!

# 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

# setSql

setSql(String sql)

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

# lambda

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

QueryWarpper的使用方法，MyBatics Plus的查询方法处理

本文地址：https://blog.csdn.net/qq_25580555/article/details/107385285