Sql 获取出席人数的百分比

我需要一份部门名单以及该部门将参加会议的人员百分比

输出：

• 销售=30%出席
• 会计=15%出席

表EMP：

EMPID FNAME LNAME DEPT 001......John......Lock...Sales 002......Lisa......Conrad...Accounting 003......Jerry.....Forts...Billing 004......Sara......Duval...Sales 那么数学部分我不确定

select sum(  )/count(*)*100

帮忙？我的大脑被炸了…

试试这个：

CREATE TABLE emp (
  empid NUMBER,
  fname VARCHAR2(20),
  dept VARCHAR2(20)
);

CREATE TABLE attendance (
  empid NUMBER,
  party_attend VARCHAR2(1)
);

INSERT INTO emp VALUES (1,' John', 'Sales');
INSERT INTO emp VALUES (2,' Lisa', 'Accounting');
INSERT INTO emp VALUES (3,' Jerry', 'Billing');
INSERT INTO emp VALUES (4,' Sara', 'Sales');

INSERT INTO attendance VALUES (1, 'Y');
INSERT INTO attendance VALUES (2, 'N');
INSERT INTO attendance VALUES (3, 'N');
INSERT INTO attendance VALUES (4, 'Y');

COMMIT;

SELECT
    e.dept,
    COUNT(DECODE(att.party_attend, 'Y', 1, NULL)) / COUNT(1) * 100 AS percentage
  FROM
    emp e JOIN attendance att ON (e.empid = att.empid)
GROUP BY e.dept;

输出：

DEPT PERCENTAGE -------------------- ---------- Accounting 0 Billing 0 Sales 100 部门百分比 -------------------- ---------- 会计0 账单0 销售额100

---

输出结果并非您所期望的，因为在您的数据中，所有参加聚会的员工都来自销售部门…

非常感谢！！这正是我想要的是，很抱歉，我刚刚制作的输出，但这就是我想要的关于如何正确使用连接和数学部分的内容

CREATE TABLE emp (
  empid NUMBER,
  fname VARCHAR2(20),
  dept VARCHAR2(20)
);

CREATE TABLE attendance (
  empid NUMBER,
  party_attend VARCHAR2(1)
);

INSERT INTO emp VALUES (1,' John', 'Sales');
INSERT INTO emp VALUES (2,' Lisa', 'Accounting');
INSERT INTO emp VALUES (3,' Jerry', 'Billing');
INSERT INTO emp VALUES (4,' Sara', 'Sales');

INSERT INTO attendance VALUES (1, 'Y');
INSERT INTO attendance VALUES (2, 'N');
INSERT INTO attendance VALUES (3, 'N');
INSERT INTO attendance VALUES (4, 'Y');

COMMIT;

SELECT
    e.dept,
    COUNT(DECODE(att.party_attend, 'Y', 1, NULL)) / COUNT(1) * 100 AS percentage
  FROM
    emp e JOIN attendance att ON (e.empid = att.empid)
GROUP BY e.dept;

DEPT PERCENTAGE -------------------- ---------- Accounting 0 Billing 0 Sales 100