編寫查詢，從EMPLOYEE表中找出哪一年最多員工加入公司，總共多少人加入。

一個叫 team 的表，里面只有一個字段name, 一共有4 條紀錄，分別是a,b,c,d, 對應四個球隊，現在四個球隊進行比賽，用一條sql 語句顯示所有可能的比賽組合。

編寫查詢，從EMPLOYEE表中查找所有員工，他們的收入高于他們部門的平均工資。

列出員工的HireDate服務年限和月份。

如何在單查詢中將EMPLOYEE表的性別Gender從“Male”更新為“Female”和從“Female”更新為“Male”？

觸發器的作用？

計算超過2名員工的部門總薪水。

如何從現有表中創建一個空表？

如何從兩個表中獲取公共記錄？

如何從表中交替提取記錄？

select MAX(TotalEmployees) from

(select YEAR(HireDate) as Year, COUNT(EmployeeID) as TotalEmployees

from EMPLOYEE

group by YEAR(HireDate)) as tmp

select a.name, b.name from #team a, #team b where a.name< b.name order by a.name;

SELECT OUTEREMPLOYEE.*, OUTEREMPLOYEE.Salary

FROM EMPLOYEE OUTEREMPLOYEE

WHERE OUTEREMPLOYEE.Salary >

(SELECT AVG(INNEREMPLOYEE.Salary)

FROM EMPLOYEE INNEREMPLOYEE

WHERE OUTEREMPLOYEE.DepartmentID = INNEREMPLOYEE.DepartmentID)

SELECT EMPLOYEE.*,

YEAR(HireDate) AS Years, MONTH(HireDate) AS Months

FROM EMPLOYEE

UPDATE EMPLOYEE

SET EMPLOYEE.Gender =

CASE EMPLOYEE.Gender

WHEN 'Male' THEN 'Female'

WHEN 'female' THEN 'Male'

END

觸發器是一中特殊的存儲過程，主要是通過事件來觸發而被執行的。它可以強化約束，來維護數據的完整性和一致性，可以跟蹤數據庫內的操作從而不允許未經許可的更新和變化。可以聯級運算。如，某表上的觸發器上包含對另一個表的數據操作，而該操作又會導致該表觸發器被觸發。

select DepartmentID, SUM(Salary) as totalSalary

from #EMPLOYEE

group by DepartmentID

having COUNT(EmployeeID) > 2

Select * into studentcopy from student where 1 = 2

Select StudentID from student

INTERSECT

Select StudentID from Exam

顯示偶數：

Select studentId

from (Select rowno, studentId from student) as t

where mod(rowno,2) = 0

顯示奇數：

Select studentId

from (Select rowno, studentId from student)

where mod(rowno,2) = 1