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;