SQL-简单查询

/*人员：LDH功能：SQL-简单查询日期：2018-7-18*/USE TSQLFundamentals2008;
GO-- Select some columns' information.
SELECT empid,lastname,firstname,address,city,country
FROM HR.Employees;-- GROUP BY
SELECT '国家' = country,COUNT(1) AS '员工个数'
FROM HR.Employees
GROUP BY country;-- Expression
SELECT '订单日期' = orderdate,YEAR(orderdate) AS '订单年份'
FROM Sales.Orders;