1.创建表1并在表中插入数据，分别指定字段和整行为缺省值

postgres=# create table table1(id int, name char(20));
postgres=# insert INTO table1 values (1, default);
postgres=# insert into table1 default values ;

2.创建表2并将表1的数据全部导入表2中

postgres=# create table table2(id int, name char(20));
postgres=# insert into table2 select * from table1;

3.创建表3和表4，并合并两个表的数据到表3

postgres=# create table table3(id int, name char(20));
postgres=# insert into table3 values(2, 'tom'),(3, 'jack');
postgres=# create table table4(id int, name char(20));
postgres=# insert into table3 values(2, 'tom'),(4, 'mary');
postgres=# merge into table4 t4 using table3 t3 on (t3.id = t4.id)
postgres-# when matched then 
postgres-# update set t4.name = t3.name
postgres-# when not matched then 
postgres-# insert values (t3.id, t3.name);

4.将表3的数据输出到文件，再将文件中的数据导入到表5

postgres=# copy table3 to '/home/omm/table0.dat';
postgres=# create table table5(like table3);
postgres=# copy table5 from '/home/omm/table0.dat';