PostgreSQL – CREATE Database
This chapter discusses about how to create a new database in your PostgreSQL. PostgreSQL provides two ways of creating a new database −
- Using CREATE DATABASE, an SQL command.
- Using createdb a command-line executable.
Using CREATE DATABASE
This command will create a database from PostgreSQL shell prompt, but you should have appropriate privilege to create a database. By default, the new database will be created by cloning the standard system database template1.
The basic syntax of CREATE DATABASE statement is as follows −
CREATE DATABASE dbname;
where dbname is the name of a database to create.
The following is a simple example, which will create testdb in your PostgreSQL schema
postgres=# CREATE DATABASE testdb; postgres-#
Using createdb Command
PostgreSQL command line executable createdb is a wrapper around the SQL command CREATE DATABASE. The only difference between this command and SQL command CREATE DATABASE is that the former can be directly run from the command line and it allows a comment to be added into the database, all in one command.
The syntax for createdb is as shown below −
createdb [option...] [dbname [description]]
The table given below lists the parameters with their descriptions.
|S. No.||Parameter & Description|
The name of a database to create.
Specifies a comment to be associated with the newly created database.
command-line arguments, which createdb accepts.
The following table lists the command line arguments createdb accepts −
|S. No.||Option & Description|
Specifies the default tablespace for the database.
Echo the commands that createdb generates and sends to the server.
Specifies the character encoding scheme to be used in this database.
Specifies the locale to be used in this database.
Specifies the template database from which to build this database.
Show help about createdb command line arguments, and exit.
Specifies the host name of the machine on which the server is running.
Specifies the TCP port or the local Unix domain socket file extension on which the server is listening for connections.
User name to connect as.
Never issue a password prompt.
Force createdb to prompt for a password before connecting to a database.
Open the command prompt and go to the directory where PostgreSQL is installed. Go to the bin directory and execute the following command to create a database.
createdb -h localhost -p 5432 -U postgres testdb password ******
The above given command will prompt you for password of the PostgreSQL admin user, which is postgres, by default. Hence, provide a password and proceed to create your new database
Once a database is created using either of the above-mentioned methods, you can check it in the list of databases using l, i.e., backslash el command as follows −
postgres-# l List of databases Name | Owner | Encoding | Collate | Ctype | Access privileges -----------+----------+----------+---------+-------+----------------------- postgres | postgres | UTF8 | C | C | template0 | postgres | UTF8 | C | C | =c/postgres + | | | | | postgres=CTc/postgres template1 | postgres | UTF8 | C | C | =c/postgres + | | | | | postgres=CTc/postgres testdb | postgres | UTF8 | C | C | (4 rows) postgres-#
Python Example for Beginners
Two Machine Learning Fields
There are two sides to machine learning:
- Practical Machine Learning:This is about querying databases, cleaning data, writing scripts to transform data and gluing algorithm and libraries together and writing custom code to squeeze reliable answers from data to satisfy difficult and ill defined questions. It’s the mess of reality.
- Theoretical Machine Learning: This is about math and abstraction and idealized scenarios and limits and beauty and informing what is possible. It is a whole lot neater and cleaner and removed from the mess of reality.
Data Science Resources: Data Science Recipes and Applied Machine Learning Recipes
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