--使用omm用户连接到本机omm数据库的5432端口，命令中的-r选项提供了对gsql命令的历史版本支持。

su - omm
gsql -r
或
gsql -d omm  -p 5432  -r

select version();
show server_version;
 \copyright

--\l命令，元命令\l的作用是显示openGauss数据库集簇中，目前有哪些数据库。

\l

--\conninfo命令，元命令\conninfo的作用是在gsql中，显示会话的连接信息。

\conninfo

--\c[onnect] [DBNAME]命令，元命令\ c[onnect] [DBNAME]的作用是在gsql中，切换连接的数据库postgres。

\c postgres

--\du命令和\dg命令，元命令\dg命令与元命令\du命令的作用类似，都是显示openGauss数据库集簇中，目前有哪些用户和角色。

\du

\dg

--\db命令，元命令\db的作用是显示openGauss数据库集簇中，目前有哪些表空间。

\db

--\dn命令，元命令\dn的作用是显示当前数据库有哪些数据库模式。

\dn

--创建表
CREATE TABLE customer_t
(  c_customer_sk             integer,   
 c_customer_id             char(5),    
 c_first_name              char(6),    
 c_last_name               char(8) 
) ;
--插入数据
INSERT INTO customer_t (c_customer_sk, c_customer_id, c_first_name,c_last_name) VALUES (3769, 5, 'Grace','White');

--\dt命令，命令\dt的作用是显示数据库中所有的表。
\dt

--\d TableName命令，元命令\d TableName的作用是查看某个表的信息。
\d customer_t

--\di IndexName命令，查看索引信息，元命令\di IndexName的作用是查看某个索引的信息。
create index idx_customer_id on customer_t(c_customer_id);
\di                 

--可以用\pset命令以不同的方法显示表：

\pset border 2
SELECT * FROM customer_t;


--打开扩展表格式模式。
\x

--查看gsql中事务是否默认为自动提交
show AUTOCOMMIT;
--测试gsql中事务默认为自动提交功能
create  table customer_new as select * from customer_t;
\q

--重新登录后看到之前创建的表customer_new：
gsql -d omm  -p 5432  -r
\dt

–测试gsql手动提交
#Opengauss默认执行完一条语句后，立即提交。可以关闭自动提交功能：
#注意：此处设置ATUOCOMMIT必须用大写！

\set AUTOCOMMIT off
   --插入一些数据
INSERT INTO customer_t (c_customer_sk, c_customer_id, c_first_name,c_last_name) VALUES    
(6885, 1, 'Joes', 'Hunter'),    
(4321, 2, 'Lily','Carter'),    
(9527, 3, 'James', 'Cook'),
(9500, 4, 'Lucy', 'Baker');
  --查看表中数据
select * from customer_t;
--执行回滚
ROLLBACK;
    --检查是否回滚成功
SELECT * FROM customer_t;

--连接数据库时，可以使用如下命令获取帮助信息。

gsql --help

--\h获取和SQL语法有关的帮助信息

\h

--\? 获取和元命令有关的帮助信息

 \？

root@modb:~# su - omm
omm@modb:~$ gsql -d omm -p 5432 -r
gsql ((openGauss 3.0.0 build 02c14696) compiled at 2022-04-01 18:12:00 commit 0 last mr  )
Non-SSL connection (SSL connection is recommended when requiring high-security)
Type "help" for help.

omm=#

omm=# select version();
                                                                        version                                                                        
-------------------------------------------------------------------------------------------------------------------------------------------------------
 (openGauss 3.0.0 build 02c14696) compiled at 2022-04-01 18:12:00 commit 0 last mr   on aarch64-unknown-linux-gnu, compiled by g++ (GCC) 7.3.0, 64-bit
(1 row)

omm=# show server_version;
 server_version 
----------------
 9.2.4
(1 row)

omm=# \copyright
GaussDB Kernel Database Management System
Copyright (c) Huawei Technologies Co., Ltd. 2018. All rights reserved.

omm=# \l
                         List of databases
   Name    | Owner | Encoding | Collate | Ctype | Access privileges 
-----------+-------+----------+---------+-------+-------------------
 omm       | omm   | UTF8     | C       | C     | 
 postgres  | omm   | UTF8     | C       | C     | 
 template0 | omm   | UTF8     | C       | C     | =c/omm           +
           |       |          |         |       | omm=CTc/omm
 template1 | omm   | UTF8     | C       | C     | =c/omm           +
           |       |          |         |       | omm=CTc/omm
(4 rows)

omm=# \conninfoomm=# 
You are connected to database "omm" as user "omm" via socket in "/tmp" at port "5432".

omm=# \du
                                                              List of roles
 Role name |                                                    Attributes                                                    | Member of 
-----------+------------------------------------------------------------------------------------------------------------------+-----------
 gaussdb   | Sysadmin                                                                                                         | {}
 omm       | Sysadmin, Create role, Create DB, Replication, Administer audit, Monitoradmin, Operatoradmin, Policyadmin, UseFT | {}

omm=# \dg
                                                              List of roles
 Role name |                                                    Attributes                                                    | Member of 
-----------+------------------------------------------------------------------------------------------------------------------+-----------
 gaussdb   | Sysadmin                                                                                                         | {}
 omm       | Sysadmin, Create role, Create DB, Replication, Administer audit, Monitoradmin, Operatoradmin, Policyadmin, UseFT | {}

omm-# \db
 pg_default | omm   | 
 pg_global  | omm   | 
(2 rows)

方法一：
omm@modb:~$ gsql -d postgres -p 5432 -r
gsql ((openGauss 3.0.0 build 02c14696) compiled at 2022-04-01 18:12:00 commit 0 last mr  )
Non-SSL connection (SSL connection is recommended when requiring high-security)
Type "help" for help.

openGauss=# \conninfo
openGauss=# You are connected to database "postgres" as user "omm" via socket in "/tmp" at port "5432".

方法二：
omm@modb:~$ gsql -d omm -p 5432 -r
gsql ((openGauss 3.0.0 build 02c14696) compiled at 2022-04-01 18:12:00 commit 0 last mr  )
Non-SSL connection (SSL connection is recommended when requiring high-security)
Type "help" for help.

omm=# \c postgres
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "postgres" as user "omm".

omm=# show AUTOCOMMIT;
 autocommit 
------------
 on
(1 row)

omm=# create  table customer_new as select * from customer_t;
INSERT 0 1
omm=# \q
omm@modb:~$ gsql -d omm  -p 5432  -r
gsql ((openGauss 3.0.0 build 02c14696) compiled at 2022-04-01 18:12:00 commit 0 last mr  )
omm=# Non-SSL connection (SSL connection is recommended when requiring high-security)
Type "help" for help.


omm=# select * from customer_new;
 c_customer_sk | c_customer_id | c_first_name | c_last_name 
---------------+---------------+--------------+-------------
          3769 | 5             | Grace        | White   
(1 row)

omm=# \dt
(2 rows)

omm=#                             List of relations
 Schema |     Name     | Type  | Owner |             Storage              
--------+--------------+-------+-------+----------------------------------
 public | customer_new | table | omm   | {orientation=row,compression=no}
 public | customer_t   | table | omm   | {orientation=row,compression=no}

omm=# \set AUTOCOMMIT off
omm=# \echo :AUTOCOMMIT
off
omm=# INSERT INTO customer_t (c_customer_sk, c_customer_id, c_first_name,c_last_name) VALUES    
omm-# (6885, 1, 'Joes', 'Hunter'),    
omm-# (4321, 2, 'Lily','Carter'),    
omm-# (9527, 3, 'James', 'Cook'),
omm-# (9500, 4, 'Lucy', 'Baker');
omm=# INSERT 0 4

omm=# select * from customer_t;
 c_customer_sk | c_customer_id | c_first_name | c_last_name 
---------------+---------------+--------------+-------------
          3769 | 5             | Grace        | White   
          6885 | 1             | Joes         | Hunter  
          4321 | 2             | Lily         | Carter  
          9527 | 3             | James        | Cook    
          9500 | 4             | Lucy         | Baker   
(5 rows)

omm=# ROLLBACK;
ROLLBACK
omm=# SELECT * FROM customer_t;
(1 row)

omm=#  c_customer_sk | c_customer_id | c_first_name | c_last_name 
---------------+---------------+--------------+-------------
          3769 | 5             | Grace        | White

omm@modb:~$ gsql --help
gsql is the openGauss interactive terminal.

Usage:
  gsql [OPTION]... [DBNAME [USERNAME]]

General options:
  -c, --command=COMMAND    run only single command (SQL or internal) and exit
  -d, --dbname=DBNAME      database name to connect to (default: "omm")
  -f, --file=FILENAME      execute commands from file, then exit
  -l, --list               list available databases, then exit
  -v, --set=, --variable=NAME=VALUE
                           set gsql variable NAME to VALUE
  -V, --version            output version information, then exit
  -X, --no-gsqlrc          do not read startup file (~/.gsqlrc)
  -1 ("one"), --single-transaction
                           execute command file as a single transaction
  -?, --help               show this help, then exit

Input and output options:
  -a, --echo-all           echo all input from script
  -e, --echo-queries       echo commands sent to server
  -E, --echo-hidden        display queries that internal commands generate
  -k, --with-key=KEY       the key for decrypting the encrypted file
  -L, --log-file=FILENAME  send session log to file
  -m, --maintenance        can connect to cluster during 2-pc transaction recovery
  -n, --no-libedit        disable enhanced command line editing (libedit)
  -o, --output=FILENAME    send query results to file (or |pipe)
  -q, --quiet              run quietly (no messages, only query outp    set record separator to zero byte
  -2, --pipeline           use pipeline to pass the password, forbidden to use in terminal
                           must use with -c or -f

Connection options:
ut)
  -C, --enable-client-encryption              enable client encryption feature
  -s, --single-step        single-step mode (confirm each query)
  -S, --single-line        single-line mode (end of line terminates SQL command)

Output format options:
  -A, --no-align           unaligned table output mode
  -F, --field-separator=STRING
                           set field separator (default: "|")
  -H, --html               HTML table output mode
  -P, --pset=VAR[=ARG]     set printing option VAR to ARG (see \pset command)
  -R, --record-separator=STRING
                           set record separator (default: newline)
  -r                       if this parameter is set,use libedit 
  -t, --tuples-only        print rows only
  -T, --table-attr=TEXT    set HTML table tag attributes (e.g., width, border)
  -x, --expanded           turn on expanded table output
  -z, --field-separator-zero
                           set field separator to zero byte
  -0, --record-separator-zero
                         -h, --host=HOSTNAME      database server host or socket directory (default: "local socket")
                           allow multi host IP address with comma separator in centralized cluster
  -p, --port=PORT          database server port (default: "5432")
  -U, --username=USERNAME  database user name (default: "omm")
  -W, --password=PASSWORD  the password of specified database user

For more information, type "\?" (for internal commands) or "\help" (for SQL
commands) from within gsql, or consult the gsql section in the openGauss documentation.