SQL-CASE表达式

/*
    人员：LDH
    功能：SQL-CASE表达式
    日期：2018-7-18
 */

USE TSQLFundamentals2008;
GO

SELECT lastname,
    region
FROM HR.Employees;

SELECT lastname,
    region = (CASE
                  WHEN region IS NULL THEN
                      '未知地区'
                  WHEN region = 'WA' THEN
                      '华盛顿特区'
                  ELSE
                      '其他地区'
              END)
FROM HR.Employees;

SELECT lastname,
    region = (CASE region
                  WHEN 'WA' THEN
                      '华盛顿特区'
                  WHEN NULL THEN
                      '未知地区'
                  ELSE
                      '其他地区'
              END)
FROM HR.Employees;