830.txt

SQL语句集锦,很多精彩的语句,希望深入SQL的朋友可以研究一下.

USE tempdb
GO
CREATE TABLE TZ (
   Z_id  int IDENTITY(1,1)PRIMARY KEY,
   Z_name varchar(20) NOT NULL)

INSERT TZ
   VALUES ('Lisa')
INSERT TZ
   VALUES ('Mike')
INSERT TZ
   VALUES ('Carla')

SELECT * FROM TZ

--Result set: This is how table TZ looks
/*Z_id   Z_name
-------------
1      Lisa
2      Mike
3      Carla
*/
CREATE TABLE TY (
   Y_id  int IDENTITY(100,5)PRIMARY KEY,
   Y_name varchar(20) NULL)

INSERT TY (Y_name)
   VALUES ('boathouse')
INSERT TY (Y_name)
   VALUES ('rocks')
INSERT TY (Y_name)
   VALUES ('elevator')

SELECT * FROM TY
--Result set: This is how TY looks:
/*Y_id  Y_name
---------------
100   boathouse
105   rocks
110   elevator
*/
/*Create the trigger that inserts a row in table TY 
when a row is inserted in table TZ*/
CREATE TRIGGER Ztrig
ON TZ
FOR INSERT AS 
   BEGIN
   INSERT TY VALUES ('')
   END

/*FIRE the trigger and find out what identity values you get 
with the @@IDENTITY and SCOPE_IDENTITY functions*/
INSERT TZ VALUES ('Rosalie')

SELECT SCOPE_IDENTITY() AS [SCOPE_IDENTITY]
GO
SELECT   @@IDENTITY AS [@@IDENTITY]
GO

--Here is the result set.
SCOPE_IDENTITY
4
/*SCOPE_IDENTITY returned the last identity value in the same scope, which was the insert on table TZ*/

@@IDENTITY
115
/*@@IDENTITY returned the last identity value inserted to TY by the trigger, which fired due to an earlier insert on TZ*/