实验过程如下、建表：
建立带引号的表名：
postgres=# create table "GaoUser"(name varchar(10),age integer);
CREATE TABLE
postgres=# select * from GaoUser;
ERROR: relation "gaouser" does not exist
LINE 1: select * from GaoUser;
^
postgres=# select * from gaouser;
ERROR: relation "gaouser" does not exist
LINE 1: select * from gaouser;
^
postgres=# select * from "GaoUser";
name | age
------+-----
(0 rows)
上述的过程表明，带引号的表和不带引号的表，不是一回事。
再进一步实验：
postgres=# create table GaoUser(name varchar(10),age integer);
CREATE TABLE
postgres=#
postgres=# create table gaouser(name varchar(10),age integer);
ERROR: relation "gaouser" already exists
postgres=#
postgres=# create table GAOUSER(name varchar(10),age integer);
ERROR: relation "gaouser" already exists
postgres=#
postgres=# select * from GaoUser;
name | age
------+-----
(0 rows)
postgres=# select * from gaouser;
name | age
------+-----
(0 rows)
postgres=#
这说明，不带引号的表名，无论大写还是小写，都是一回事。
进一步的实验，可以验证此看法。
postgres=# insert into GaoUser values('user001',25);
INSERT 0 1
postgres=# insert into "GaoUser" values('user002',40);
INSERT 0 1
postgres=# select * from GaoUser;
name | age
---------+-----
user001 | 25
(1 row)
postgres=# select * from gaouser;
name | age
---------+-----
user001 | 25
(1 row)
postgres=#
postgres=# select * from "GaoUser";
name | age
---------+-----
user002 | 40
(1 row)
postgres=# insert into GaoUser values('User003',27);
INSERT 0 1
postgres=# select * from GaoUser;
name | age
---------+-----
user001 | 25
User003 | 27
(2 rows)
postgres=# insert into "GaoUser" values('User004',42);
INSERT 0 1
postgres=# select * from "GaoUser";
name | age
---------+-----
user002 | 40
User004 | 42
(2 rows)
postgres=#
