一.什麼是AbstractWrapper
QueryWrapper(LambdaQueryWrapper) 和 UpdateWrapper(LambdaUpdateWrapper) 的父類
用於生成 sql 的 where 條件, entity 屬性也用於生成 sql 的 where 條件
注意: entity 生成的 where 條件與 使用各個 api 生成的 where 條件沒有任何關聯行爲
1.1wapper的關係繼承圖:
wapper介紹 :
Wrapper : 條件構造抽象類,最頂端父類,抽象類中提供4個方法西面貼源碼展示
AbstractWrapper : 用於查詢條件封裝,生成 sql 的 where 條件
AbstractLambdaWrapper : Lambda 語法使用 Wrapper統一處理解析 lambda 獲取 column。
LambdaQueryWrapper :看名稱也能明白就是用於Lambda語法使用的查詢Wrapper
LambdaUpdateWrapper : Lambda 更新封裝Wrapper
QueryWrapper : Entity 對象封裝操作類,不是用lambda語法
UpdateWrapper : Update 條件封裝,用於Entity對象更新操作
二.方法解釋
2.1 allEq
allEq(Map<R, V> params)
allEq(Map<R, V> params, boolean null2IsNull)
allEq(boolean condition, Map<R, V> params, boolean null2IsNull)
個別參數說明:
params
: key
爲數據庫字段名,value
爲字段值null2IsNull
: 爲true
則在map
的value
爲null
時調用 isNull 方法,爲false
時則忽略value
爲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)
個別參數說明:
filter
: 過濾函數,是否允許字段傳入比對條件中,說到底解釋key裏面要包含某個字符串比如下面“a”,name和age因爲包含了a才能查詢出來params
與 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'
2.2eq
eq(R column, Object val)
eq(boolean condition, R column, Object val)
- 等於 =
- 例:
eq("name", "老王")
--->name = '老王'
2.3ne
ne(R column, Object val)
ne(boolean condition, R column, Object val)
- 不等於 <>
- 例:
ne("name", "老王")
--->name <> '老王'
2.4gt
gt(R column, Object val)
gt(boolean condition, R column, Object val)
- 大於 >
- 例:
gt("age", 18)
--->age > 18
2.5ge
ge(R column, Object val)
ge(boolean condition, R column, Object val)
- 大於等於 >=
- 例:
ge("age", 18)
--->age >= 18
2.6lt
lt(R column, Object val)
lt(boolean condition, R column, Object val)
- 小於 <
- 例:
lt("age", 18)
--->age < 18
2.7le
le(R column, Object val)
le(boolean condition, R column, Object val)
- 小於等於 <=
- 例:
le("age", 18)
--->age <= 18
2.8between
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
2.9notBetween
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
2.10like
like(R column, Object val)
like(boolean condition, R column, Object val)
- LIKE '%值%'
- 例:
like("name", "王")
--->name like '%王%'
2.11notLike
notLike(R column, Object val)
notLike(boolean condition, R column, Object val)
- NOT LIKE '%值%'
- 例:
notLike("name", "王")
--->name not like '%王%'
2.12likeLeft
likeLeft(R column, Object val)
likeLeft(boolean condition, R column, Object val)
- LIKE '%值'
- 例:
likeLeft("name", "王")
--->name like '%王'
2.13likeRight
likeRight(R column, Object val)
likeRight(boolean condition, R column, Object val)
- LIKE '值%'
- 例:
likeRight("name", "王")
--->name like '王%'
2.14isNull
isNull(R column)
isNull(boolean condition, R column)
- 字段 IS NULL
- 例:
isNull("name")
--->name is null
2.15isNotNull
isNotNull(R column)
isNotNull(boolean condition, R column)
- 字段 IS NOT NULL
- 例:
isNotNull("name")
--->name is not null
2.16in
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)
2.17notIn
notIn(R column, Collection<?> value)
notIn(boolean condition, R column, Collection<?> value)
- 字段 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)
2.18inSql
inSql(R column, String inValue)
inSql(boolean condition, R column, String inValue)
- 字段 IN ( sql語句 )
- 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)
2.19notInSql
notInSql(R column, String inValue)
notInSql(boolean condition, R column, String inValue)
- 字段 NOT IN ( sql語句 )
- 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")
--->age not in (select id from table where id < 3)
2.20groupBy
groupBy(R... columns)
groupBy(boolean condition, R... columns)
- 分組:GROUP BY 字段, ...
- 例:
groupBy("id", "name")
--->group by id,name
2.21orderByAsc
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
2.22orderByDesc
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
2.23orderBy
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
2.24having
having(String sqlHaving, Object... params)
having(boolean condition, String sqlHaving, Object... params)
- HAVING ( sql語句 )
- 例:
having("sum(age) > 10")
--->having sum(age) > 10
- 例:
having("sum(age) > {0}", 11)
--->having sum(age) > 11
2.25or
or()
or(boolean condition)
- 拼接 OR
注意事項:
主動調用or
表示緊接着下一個方法不是用and
連接!(不調用or
則默認爲使用and
連接)
- 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')
2.26and
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')
2.27nested
nested(Consumer<Param> consumer)
nested(boolean condition, Consumer<Param> consumer)
- 正常嵌套 不帶 AND 或者 OR
- 例:
nested(i -> i.eq("name", "李白").ne("status", "活着"))
--->(name = '李白' and status <> '活着')
2.28apply
apply(String applySql, Object... params)
apply(boolean condition, String applySql, Object... params)
- 拼接 sql
注意事項:
該方法可用於數據庫函數 動態入參的params
對應前面applySql
內部的{index}
部分.這樣是不會有sql注入風險的,反之會有!
- 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'")
2.29last
last(String lastSql)
last(boolean condition, String lastSql)
- 無視優化規則直接拼接到 sql 的最後
注意事項:
只能調用一次,多次調用以最後一次爲準 有sql注入的風險,請謹慎使用
- 例:
last("limit 1")
2.30exists
exists(String existsSql)
exists(boolean condition, String existsSql)
- 拼接 EXISTS ( sql語句 )
- 例:
exists("select id from table where age = 1")
--->exists (select id from table where age = 1)
2.31notExists
notExists(String notExistsSql)
notExists(boolean condition, String notExistsSql)
- 拼接 NOT EXISTS ( sql語句 )
- 例:
notExists("select id from table where age = 1")
--->not exists (select id from table where age = 1)
三.QueryWrapper
3.1select
select(String... sqlSelect)
select(Predicate<TableFieldInfo> predicate)
select(Class<T> entityClass, Predicate<TableFieldInfo> predicate)
- 設置查詢字段
說明:
以上方分法爲兩類.
第二類方法爲:過濾查詢字段(主鍵除外),入參不包含 class 的調用前需要wrapper
內的entity
屬性有值! 這兩類方法重複調用以最後一次爲準
- 例:
select("id", "name", "age")
- 例:
select(i -> i.getProperty().startsWith("test"))
四.UpdateWrapper
說明:
繼承自 AbstractWrapper
,自身的內部屬性 entity
也用於生成 where 條件
及 LambdaUpdateWrapper
, 可以通過 new UpdateWrapper().lambda()
方法獲取!
4.1set
set(String column, Object val)
set(boolean condition, String column, Object val)
- SQL SET 字段
- 例:
set("name", "老李頭")
- 例:
set("name", "")
--->數據庫字段值變爲空字符串 - 例:
set("name", null)
--->數據庫字段值變爲null
4.2setSql
setSql(String sql)
- 設置 SET 部分 SQL
- 例:
setSql("name = '老李頭'")
4.3lambda
- 獲取
LambdaWrapper
在QueryWrapper
中是獲取LambdaQueryWrapper
在UpdateWrapper
中是獲取LambdaUpdateWrapper
五.使用 Wrapper 自定義SQL
需求來源:
在使用了mybatis-plus
之後, 自定義SQL的同時也想使用Wrapper
的便利應該怎麼辦? 在mybatis-plus
版本3.0.7
得到了完美解決 版本需要大於或等於3.0.7
, 以下兩種方案取其一即可
Service.java
mysqlMapper.getAll(Wrappers.<MysqlData>lambdaQuery().eq(MysqlData::getGroup, 1));
方案一 註解方式 Mapper.java
@Select("select * from mysql_data ${ew.customSqlSegment}")
List<MysqlData> getAll(@Param(Constants.WRAPPER) Wrapper wrapper);
方案二 XML形式 Mapper.xml
<select id="getAll" resultType="MysqlData">
SELECT * FROM mysql_data ${ew.customSqlSegment}
</select>