[SQL] Ranking
先建立一個練習表格：
CREATE TABLE Department
(
id SERIAL PRIMARY KEY, name VARCHAR NOT NULL
);
CREATE TABLE Employee
(
id SERIAL PRIMARY KEY, name VARCHAR NOT NULL, salary INT, dep_id INT, );
INSERT INTO Employee(name, salary, dep_id) VALUES ('Mandy', 45000, 2);
INSERT INTO Employee(name, salary, dep_id) VALUES ('Emily', 43000, 1);
INSERT INTO Employee(name, salary, dep_id) VALUES ('Sylvia', 26000, 2);
INSERT INTO Employee(name, salary, dep_id) VALUES ('Eva', 48000, 3);
INSERT INTO Employee(name, salary, dep_id) VALUES ('Sandra', 33000, 3);
INSERT INTO Employee(name, salary, dep_id) VALUES ('Lily', 28000, 2);
INSERT INTO Employee(name, salary, dep_id) VALUES ('April', 50000, 1);
INSERT INTO Employee(name, salary, dep_id) VALUES ('Cindy', 43000, 1);
INSERT INTO Employee(name, salary, dep_id) VALUES ('Kay', 40000, 3);
INSERT INTO Department(name) VALUES ('IT');
INSERT INTO Department(name) VALUES ('RD');
INSERT INTO Department(name) VALUES ('QA');
資料排序 直接用 ORDER BY 無法得到秩(排名)
