SQL 별칭

1 개요

SQL Aliases

SQL 별칭

• 컬럼명, 테이블명 등에 특수문자가 포함되거나 긴 경우, 짧고 쉬운 이름으로 대체할 수 있음

2 예시 1: 컬럼명

• 별칭 미사용

mysql> SELECT COUNT(*) FROM Customers;
+----------+
| COUNT(*) |
+----------+
|        3 |
+----------+

• 별칭 사용

mysql> SELECT COUNT(*) AS cnt FROM Customers;
+-----+
| cnt |
+-----+
|   3 |
+-----+

3 예시 2: 컬럼명 2

• 별칭 미사용

mysql> SELECT CustomerName, CONCAT(Address,', ',City,', ',PostalCode,', ',Country) FROM Customers WHERE CustomerID=4;
+-----------------+--------------------------------------------------------+
| CustomerName    | CONCAT(Address,', ',City,', ',PostalCode,', ',Country) |
+-----------------+--------------------------------------------------------+
| Around the Horn | 120 Hanover Sq., London, WA1 1DP, UK                   |
+-----------------+--------------------------------------------------------+

• 별칭 사용

mysql> SELECT CustomerName, CONCAT(Address,', ',City,', ',PostalCode,', ',Country) AS Address FROM Customers WHERE CustomerID=4;
+-----------------+--------------------------------------+
| CustomerName    | Address                              |
+-----------------+--------------------------------------+
| Around the Horn | 120 Hanover Sq., London, WA1 1DP, UK |
+-----------------+--------------------------------------+

4 예시 3: 테이블명

• 별칭 미사용

SELECT Orders.OrderID, Orders.OrderDate, Customers.CustomerName
FROM Customers, Orders
WHERE Customers.CustomerName="Around the Horn" AND Customers.CustomerID=Orders.CustomerID;

• 별칭 사용

SELECT o.OrderID, o.OrderDate, c.CustomerName
FROM Customers AS c, Orders AS o
WHERE c.CustomerName="Around the Horn" AND c.CustomerID=o.CustomerID;

5 참고 자료

• http://www.w3schools.com/sql/sql_alias.asp