SQL .
SELECT [ALL | DISTINCT | DISTINCTROW | [TOP n [PERCENT]]] FROM table
| ALL | . , . : SELECT ALL * FROM Employees ORDER BY EmployeeID; SELECT * FROM Employees ORDER BY EmployeeID; |
| DISTINCT | , . , SELECT DISTINCT LastName FROM Employees; , , DISTINCT . , . , DISTINCT, ,.. - . : ( ), . |
| DISTINCTROW | . , , Customers Orders CustomerID. Customers CustomerID, Orders , .. . , , SELECT DISTINCTROW CompanyName FROM Customers INNER JOIN Orders ON Customers.CustomerID = Orders.CustomerID ORDER BY CompanyName; , , . DISTINCTROW , , , . , DISTINCTROW . : , ( ). |
| TOP n [PERCENT] | (n) (n PERCENT) . , 25 1994 SELECT TOP 25 FirstName, LastName FROM Students WHERE GraduationYear = 1994 ORDER BY GradePointAverage DESC; ORDER BY 25 , WHERE. TOP 25- 26- , 26 . 10% : SELECT TOP 10 PERCENT FirstName, LastName FROM Students WHERE GraduationYear = 1994 ORDER BY GradePointAverage ASC; n , TOP , . |
DISTINCT UniqueValues Yes , DISTINCTROW Yes UniqueRecords. TOP TopValues Top Values Query Design. PERCENT % .
|
|
|
Clients
| FirstName | ClientID |
| Bob | |
| Adam | |
| Beverly | |
| Bob |
Invoices
| ClientID | InvoiceID |
SELECT ALL FirstName FROM Clients INNER JOIN Invoices
ON Clients.ClientID = Invoices.ClientID;
:
| Result | Updatable |
| Bob Bob Adam Adam Adam Bob Bob | Yes |
.
SELECT DISTINCT FirstName FROM Clients INNER JOIN Invoices
ON Clients.ClientID = Invoices.ClientID;
:
| Result | Updatable |
| Bob Adam | No |
.
SELECT DISTINCTROW FirstName FROM Clients INNER JOIN Invoices
ON Clients.ClientID = Invoices.ClientID;
:
| Result | Updatable |
| Bob Adam Bob | Yes |
.
SELECT TOP 5 FirstName FROM Clients INNER JOIN Invoices
ON Clients.ClientID = Invoices.ClientID ORDER BY Invoices.InvoiceID;
5
| Result | Updatable |
| Bob Bob Adam Adam Adam | Yes |
