A(id,name)
B(id,name,add)
从A表复制数据到B表,B表多出来的那个字段默认为空
INSERT INTO B (id,name,add) SELECT id,name,null FROM A
mysql 下是这样的。INSERT INTO B (id,name) SELECT id,name FROM A
INSERT INTO B (id,name,add) SELECT id,name,'' FROM A
insert into B select id,name from A
INSERT INTO B (id,name,add) SELECT *,null FROM A
只要不写那个字段就行了