SQL语言常用的一些命令各代码

				/*一个条件*/
				
				CREATE TABLE P1
( 
 PNO NUMERIC NOT NULL,
				
 PNAME TEXT NOT NULL, 
				
 COLOR CHAR(2) NOT NULL, 
				
 WEIGHT INT
)
				
				
				

alter table P1 add CONSTRAINT  C4 CHECK(WEIGHT				
				
				
				
				/*两个条件*/
				color='红'时，weight				
CREATE TABLE P1
				
( 
 PNO int NOT NULL,
				
 PNAME TEXT NOT NULL, 
				
 COLOR CHAR(2) NOT NULL, 
				
 WEIGHT INT,
 
				constraint c4
check(weight