Exercise 3-2-1

Query which employees work in Dallas using an EXISTS subquery. (scott/tiger) 請以exists相關式子查詢，查詢哪些員工是在Dallas上班。 (scott/tiger)

List all employees’ IDs and salaries if their salary is below 1000 using an EXISTS subquery. (scott/tiger) 請以exists一般子查詢，若有員工薪水低於1000，列出全部員工的員工編號與薪資所得。(scott/tiger)

Query which medical records have an employee identity (excluding empty ID numbers) using an EXISTS subquery. 請以exists相關式子查詢，查詢哪些病歷資料有員工身份(排除空白身份證號)。

Count the number of registrations in September year 90 if the employee was born after the year 70 using an EXISTS subquery. 請以exists一般子查詢，若有員工是在民國70年次以後出生的，則統計90年9月掛號的掛號人次。

List department codes for departments that had morning shift on September 1, year 90, but no afternoon shift using an EXISTS subquery. 請以exists相關式查詢，列出90年9月1日上午有開診，但下午沒有開診的科別代碼。