gsql是openGauss提供在命令行下运行的数据库连接工具，可以通过此工具连接服务器并对其进行操作和维护，除了具备操作数据库的基本功能，gsql还提供了若干高级特性，便于用户使用。
1.使用gsql命令连接数据库
–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
2.在gsql中查看数据库的版本、pg基础版本和版权信息
select version();
show server_version;
\copyright
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)
3.常见元命令的使用
–\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
omm=# \l
List of databases
Name | Owner | Encoding | Collate | Ctype | Access privileges
-----------+-------+----------+---------+-------+-------------------
omm | omm | UTF8 | C | C |
omm=# 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=# \conninfo
You are connected to database "omm" as user "omm" via socket in "/tmp" at port "5432".
omm=#
omm=#
omm=#
omm=# \c
could not connect to server: Invalid argument
Is the server running on host "119" (0.0.0.119) and accepting
TCP/IP connections on port 5432?
Previous connection kept
omm=#
omm-#
omm-#
omm-#
omm-#
omm-# \c postgres
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "postgres" as user "omm".
openGauss-# \du
WARNING: Session unused timeout.
FATAL: terminating connection due to administrator command
could not send data to server: Broken pipe
The connection to the server was lost. Attempting reset: Succeeded.
openGauss-# \q
omm@modb:~$ gsql -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=#
omm=#
omm=#
omm=#
omm=# \du
gaussdb | Sysadmin | {}
omm | Sysadmin, Create role, Create DB, Replication, Administer audit, Monitoradmin, Operatoradmin, Policyadmin, UseFT | {}
List of roles
Role name | Attributes | Member of
-----------+------------------------------------------------------------------------------------------------------------------+-----------
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=#
omm=#
omm=# \db
List of tablespaces
Name | Owner | Location
------------+-------+----------
pg_default | omm |
pg_global | omm |
(2 rows)
omm=# \dn
List of schemas
Name | Owner
-----------------+-------
blockchain | omm
cstore | omm
db4ai | omm
dbe_perf | omm
dbe_pldebugger | omm
dbe_pldeveloper | omm
pkg_service | omm
public | omm
snapshot | omm
sqladvisor | omm
(10 rows)
omm=# CREATE TABLE customer_t
omm-# ( c_customer_sk integer,
omm(# c_customer_id char(5),
omm(# omm(# c_first_name char(6),
c_last_name char(8)
omm(# ) ;
CREATE TABLE
omm=#
omm=# INSERT INTO customer_t (c_customer_sk, c_customer_id, c_first_name,c_last_name) VALUES (3769, 5, 'Grace','White');
INSERT 0 1
omm=#
omm=#
omm=# \dt
List of relations
Schema | Name | Type | Owner | Storage
--------+------------+-------+-------+----------------------------------
public | customer_t | table | omm | {orientation=row,compression=no}
(1 row)
omm=# \d customer_t
omm=# Table "public.customer_t"
Column | Type | Modifiers
---------------+--------------+-----------
c_customer_sk | integer |
c_customer_id | character(5) |
c_first_name | character(6) |
c_last_name | character(8) |
omm=#
omm=#
omm=# create index idx_customer_id on customer_t(c_customer_id);
CREATE INDEX
omm=#
omm=#
omm=# \di
(1 row)
omm=# List of relations
Schema | Name | Type | Owner | Table | Storage
--------+-----------------+-------+-------+------------+---------
public | idx_customer_id | index | omm | customer_t |
omm=#
omm=#
omm=# \di
public | idx_customer_id | index | omm | customer_t |
(1 row)
omm=# List of relations
Schema | Name | Type | Owner | Table | Storage
--------+-----------------+-------+-------+------------+---------
omm=#
omm=#
omm=# \pset border 2
Border style is 2.
omm=# SELECT * FROM customer_t;
+---------------+---------------+--------------+-------------+
| c_customer_sk | c_customer_id | c_first_name | c_last_name |
+---------------+---------------+--------------+-------------+
| 3769 | 5 | Grace | White |
+---------------+---------------+--------------+-------------+
(1 row)
omm=# \x
Expanded display is on.
omm=# show AUTOCOMMIT;
+-[ RECORD 1 ]----+
| autocommit | on |
+------------+----+
omm=# create table customer_new as select * from customer_t;
INSERT 0 1
omm=#
omm=# \q
4.gsql中的事务：测试gsql中的默认事务自动提交功能
–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 postgres -p 5432 -r
\dt
5.gsql中的事务：测试gsql中的事务手动提交功能
–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;
omm@modb:~$ gsql -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=# \dt
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}
(2 rows)
omm=# \set 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-# omm-# (9527, 3, 'James', 'Cook'),
(9500, 4, 'Lucy', 'Baker');
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;
c_customer_sk | c_customer_id | c_first_name | c_last_name
---------------+---------------+--------------+-------------
3769 | 5 | Grace | White
(1 row)
6.gsql相关的帮助
–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
\？
