SQL SERVER 2005 高级查询（子查询查询）

--SQL高级程序设计：子查询

use AdventureWorks
GO

SELECT DISTINCT EmployeeID FROM HumanResources.JobCandidate WHERE EmployeeID IS NOT NULL;

SELECT e.EmployeeID,FirstName,LastName
FROM HumanResources.Employee e
INNER JOIN Person.Contact c
ON e.ContactID = c.ContactID
WHERE e.EmployeeID IN (SELECT DISTINCT EmployeeID FROM HumanResources.JobCandidate
WHERE EmployeeID IS NOT NULL)

SELECT DISTINCT EmployeeID FROM HumanResources.JobCandidate WHERE EmployeeID IS NOT NULL

SELECT e.EmployeeID,FirstName,LastName
FROM HumanResources.Employee e
INNER JOIN Person.Contact c
ON e.ContactID = c.ContactID
WHERE e.EmployeeID NOT IN (
SELECT DISTINCT EmployeeID
FROM HumanResources.JobCandidate
WHERE EmployeeID IS NOT NULL
)

SELECT CustomerID,MIN((OrderDate)) AS OrderDate
INTO #MinOrderDates
FROM Sales.SalesOrderHeader
GROUP BY CustomerID
ORDER BY CustomerID

SELECT o.CustomerID,o.SalesOrderID,o.OrderDate
from Sales.SalesOrderHeader o
inner join #MinOrderDates t
on o.CustomerID = t.CustomerID
and o.OrderDate = t.OrderDate
order by o.CustomerID

DROP TABLE #MinOrderHeaders

SELECT O1.CustomerID,o1.SalesOrderID,o1.OrderDate
FROM Sales.SalesOrderHeader o1
WHERE o1.OrderDate = (SELECT MIN(o2.OrderDate)
FROM Sales.SalesOrderHeader o2
WHERE O2.CustomerID = o1.CustomerID)
ORDER BY CustomerID

SELECT c.LastName,ISNULL(CAST((SELECT MIN(OrderDate) FROM Sales.SalesOrderHeader o
WHERE o.ContactID = c.ContactID) AS VARCHAR),'NEVER RECORD') AS "Order Date"
FROM Person.Contact c

SELECT e.EmployeeID,FirstName,LastName
FROM HumanResources.Employee e
INNER JOIN Person.Contact c
ON e.ContactID = c.ContactID
WHERE EXISTS(SELECT DISTINCT EmployeeID FROM HumanResources.JobCandidate jc
WHERE EmployeeID = e.EmployeeID)

IF NOT EXISTS(SELECT 'True' FROM SYS.DATABASES WHERE name = 'DBCreateTest')
BEGIN
CREATE DATABASE DBCreateTest
END
ELSE
BEGIN
PRINT 'DATABASE ALREADY EXISTS.'
END
GO

SELECT OrderDate,CONVERT(CHAR(12),OrderDate,112) AS "Converted"
FROM Sales.SalesOrderHeader
WHERE SalesOrderID = '43660'