How to use the 'as' keyword to alias a table in Oracle?

问题

I\'m trying to execute this query in Oracle SQL Developer:

SELECT G.Guest_ID, G.First_Name, G.Last_Name
FROM Guest AS G
  JOIN Stay AS S ON G.Guest_ID = S.Guest_ID
WHERE G.City = \'Miami\' AND S.Room = \'222\';

However, I get the following error:

ORA-00933: SQL command not properly ended
00933. 00000 - \"SQL command not properly ended\"
*Cause:
*Action:
Error at Line: 2 Column: 12

I don\'t see any problem in line 2 and the error is not very descriptive. It appears to be something to do with the as keyword. If I remove it, it works fine. However, I want my queries to be very verbose. Therefore, I must figure out a way to fix whatever the problem is without removing the as keyword.

This is the structure of the tables involved:

CREATE TABLE GUEST
(
  GUEST_ID       NUMBER               NOT NULL,
  LAST_NAME      VARCHAR2(50 BYTE),
  FIRST_NAME     VARCHAR2(50 BYTE),
  CITY           VARCHAR2(50 BYTE),
  LOYALTY_NUMBER VARCHAR2(10 BYTE)    
);

CREATE TABLE STAY
(
  STAY_ID        NUMBER                         NOT NULL,
  GUEST_ID       NUMBER                         NOT NULL,
  HOTEL_ID       NUMBER                         NOT NULL,
  START_DATE     DATE,
  NUMBER_DAYS    NUMBER, 
  ROOM           VARCHAR2(10 BYTE)
);

Thanks for any help in advance.

回答1:

You can use AS for table aliasing on many SQL servers (at least MsSQL, MySQL, PostrgreSQL) but it's always optional and on Oracle it's illegal.

So remove the AS :

SELECT G.Guest_ID, G.First_Name, G.Last_Name
FROM Guest G

回答2:

Omit the AS for table alias in Oracle.

SELECT G.Guest_ID, G.First_Name, G.Last_Name
FROM Guest G
  JOIN Stay S ON G.Guest_ID = S.Guest_ID
WHERE G.City = 'Miami' AND S.Room = '222';

This will give you the output without errors.

来源：https://stackoverflow.com/questions/21145028/how-to-use-the-as-keyword-to-alias-a-table-in-oracle