SQL Server 约束的增删改

table orders ( docentry int constraint pk_id primary key not null, --红色部分非空约束 customer_number varchar(20), order_number varchar(20) , order_line int, order_price float )

　　（2）修改非空约束

alter table orders 
alter column customer_number varchar(20) not null

alter table orders 
alter column order_number varchar(20) not null

alter table orders 
alter column order_line int not null

SQL Server 约束的增删改

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