1.在创建表时复制
create table table_name
as select column1，column2,...... from old_table;
例：
create table userinfo2
as select name,num from userinfo;
若要复制全部数据，select * 即可
create table userinfo2
as select * from userinfo;
2.对已经创建的表复制数据
insert into table_name
(column1,column2,......)
select column1,column2 from old_table;
复制全部数据：
insert into table_name
select * from old_table;
说明：
1.对已存在表复制时，字段名必须存在。
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