Postgresql

1、创建数据库、查看数据库

postgres-# CREATE DATABASE runoobdb;
ERROR:  syntax error at or near "CREATE"
LINE 2: CREATE DATABASE runoobdb;
        ^
postgres=# CREATE DATABASE runoobdb;
CREATE DATABASE
postgres=# \l
                             List of databases
   Name    |  Owner   | Encoding | Collate | Ctype |   Access privileges   
-----------+----------+----------+---------+-------+-----------------------
 postgres  | postgres | UTF8     | C       | C     | 
 runoobdb  | postgres | UTF8     | C       | C     | 
 template0 | postgres | UTF8     | C       | C     | =c/postgres          +
           |          |          |         |       | postgres=CTc/postgres
 template1 | postgres | UTF8     | C       | C     | =c/postgres          +
           |          |          |         |       | postgres=CTc/postgres
(4 rows)

2、查看表

postgres=# \d company
                  Table "public.company"
 Column  |     Type      | Collation | Nullable | Default 
---------+---------------+-----------+----------+---------
 id      | integer       |           | not null | 
 name    | text          |           | not null | 
 age     | integer       |           | not null | 
 address | character(50) |           |          | 
 salary  | real          |           |          | 
Indexes:
    "company_pkey" PRIMARY KEY, btree (id)

3、当存在多个数据库时，如何连接到指定的数据库

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

postgres-# \c dayudb
You are now connected to database "dayudb" as user "postgres".
dayudb-#

或者也可以通过ip加端口的方式连接到数据库，默认采用的如下方式连接：

oracle:~ dayu$ /Library/PostgreSQL/11/scripts/runpsql.sh

Server [localhost]:

Database [postgres]:

Port [5432]:

Username [postgres]: postgres

Password for user postgres:

psql (11.4)

Type "help" for help

4、创建用户

dayudb=# create user dayu with password 'dayu';
CREATE ROLE

dayudb=# \d

List of relations

Schema | Name | Type | Owner

--------+---------+-------+----------

public | company | table | postgres

public | test | table | postgres

(2 rows)

dayudb=# GRANT ALL PRIVILEGES ON database dayudb to dayu;

GRANT