Mybatisplus 条件结构器 QueryWrapper
QueryWrapper：Entity 对象封装操作类
LambdaQueryWrapper：用于 Lambda 语法应用的查问 Wrapper
例：
QueryWrapper<User> queryWrapper = QueryGenerator.initQueryWrapper(user,null);
queryWrapper.eq("user_name",user.getUserName());
IPage<User> page = new Page<>(pageNo, pageSize);
IPage<User> pageList = userServer.page(page, queryWrapper);
例：
protected FrfReptPlan getFrfReptPlan(String contractId,String perdNum,String costType){return frfReptPlanService.getOne(new LambdaQueryWrapper<FrfReptPlan>()
.eq(FrfReptPlan::getFpfContrId, contractId)
.eq(FrfReptPlan::getPerdNum, perdNum)
.eq(FrfReptPlan::getCostType,costType));
}
罕用办法：
办法 形容 等价 例子
eq 等于 = eq("name","吕布")name="吕布"
ne 不等于 <> ne("name","吕布") 含意：name<>"吕布"
gt 大于 > gt("age","10") 含意：age>10
lt 小于 < lt("age","10") 含意：age<10
ge 大于等于 >= ge("age","10") 含意：age>=10
le 小于等于 <= le("age","10") 含意：age<=10
between 在值 1 值 2 之间 between and between("age","10","18") 含意：10<=age<=18
notBetween 不在值 1 值 2 之间 not bteween and notBetween("age","10","18") 含意：18<age 或 age<10
like 含糊查问 like like("name","吕") 含意：name like "% 吕 %"
notLike 含糊查问 not Like notLike("name","吕") 含意：name not like "% 吕 %"
likLeft 含糊查问 likLeft("name","吕") 含意：name like "% 吕"
likeRight 含糊查问 likeRight("name","吕") 含意：name like "吕 %"
isNull 是否为空
isNotNull 字段为不空
in in in age in (10,15,20) 含意：age 在 10,15,20 之间
notIn not in not in age not in (10,15,20) 含意：age 不在 10,15,20 之间
inSql in(sql) inSql("id","select id from table") 含意：id in (select id from table)
notInSql not in(sql) notInSql("id","select id from table") 含意：id not in (select id from table)
groupBy 分组 group by groupBy(id,name) 含意：group by id,name
orderByAsc 升序 orderByAsc(id,name) 含意：order by id asc,name asc
orderByDesc 降序 orderByDesc(id,name) 含意：order by id desc,name desc
orderBy 排序 order by orderBy(true,true,"id","name") 含意：order by id asc,name asc
having having
or 或 or eq("id","1") or eq("id","2") 含意：id='1' or id='2'
and 且 and eq("id","1") and eq("id","2") 含意：id='1' and id='2'
apply 拼接 sql
last 忽视优化规定间接拼接 sql 最初
exists 拼接
notExists 拼接
nested 失常嵌套，不带 and 或者 or