sum(数字字段) avg(数字字段). sum()和avg()两个函数只要是数值型数据都可以使用. 查询所有雇员的总工资和平均工资 SQL> select sum(sal),avg(sal) from emp; SUM(SAL) AVG(SAL) --- --- 29025 2073.21429 1. 2. 3. 4. 5. 获取平均服务年限 SQL> select trunc (avg(months_between(sysdate,hire...
# Java Stream Bigdecimal求和跳过null的实现## 一、整体流程首先,我们需要创建一个 BigDecimal 类型的 Stream 流,并使用 filter 方法来跳过 null 值,最后使用 reduce 方法对流中的元素进行求和。下面是具体的步骤表格:| 步骤 | 描述 || --- | --- || 1 | 创建一个 BigDecima List java Java java stre...
stream().map(User::getSalary).reduce(BigDecimal.ZERO, BigDecimal::add); //平均薪资 BigDecimal avgSalary = userList.stream().map(User::getSalary).reduce(BigDecimal.ZERO, BigDecimal::add).divide(BigDecimal.valueOf(userList.size()), 2, BigDecimal.ROUND_HALF_UP); //打印统计结果 System.out....
min(BigDecimal::compareTo).get(); // 薪资总和 BigDecimal sumMoney = userList.stream().map(User::getMoney).reduce(BigDecimal.ZERO, BigDecimal::add); //平均薪资 BigDecimal avgMoney = userList.stream().map(User::getMoney).reduce(BigDecimal.ZERO, BigDecimal::add).divide(BigDecimal.valueOf(user...
private BigDecimal score; private Integer rank; public Student(String level, BigDecimal score) { this.level = level; this.score = score; } public Student(int id, String name, String school, String level, Integer age, BigDecimal score) { ...
studentList.add(new Student(7,"e","三中","二年级",15, new BigDecimal(5))); } // 等价于SQL: // select school,sum(score) // from students // where age is not null and age >=9 and age <= 16 // group by school // order by sum(score) desc ...
this.max : other.max; this.avg = this.sum.divide(BigDecimal.valueOf(this.count), 2, BigDecimal.ROUND_HALF_UP); return this; } } List<Order> orders = getOrders(); Map<String, Optional<ProvinceCityStatistics>> groupedMap = orders.stream().collect( Collectors.groupingBy(order -> order.get...
类似sql的 group by语义 简化处理分组和聚合的逻辑, 如果用原生stream需要写可能一大串逻辑。 代码语言:javascript 代码运行次数:0 运行 AI代码解释 JDFrame<Student> frame = JDFrame.from(studentList); // 等价于 select school,sum(age) ... group by school List<FI2<String, BigDecimal>> a = frame....
类似sql的 group by语义 简化处理分组和聚合的逻辑, 如果用原生stream需要写可能一大串逻辑. JDFrame<Student> frame = JDFrame.from(studentList);//等价于 select school,sum(age) ... group by schoolList<FI2<String, BigDecimal>> a =frame.groupBySum(Student::getSchool, Student::getAge).toLists()...
Collectors.summingInt(Object::getNum)));//分组后根据某个属性求和 BigDecimal型Map<String, BigDecimal> data =list.stream().collect(Collectors.groupingBy(Object::getWarehouseCode, Collectors.mapping(Object::getAvg, Collectors.reducing(BigDecimal.ZERO, BigDecimal::add)));//分组后收集某个属性的值Map<Str...