PostgreSQL Schema

PostgreSQL Schema

• PostgreSQL Schema
  • Using CREATE SCHEMA
    • Syntax
    • Syntax to Create Table in Schema
    • Example
  • Using Drop Schema
    • Advantages of using a Schema

A schema is a named collection of tables. A schema can also contain views, indexes, sequences, data types, operators, and functions. Schemas are analogous to directories at the operating system level, except that schemas cannot be nested. PostgreSQL statement CREATE SCHEMA creates a schema.

Using CREATE SCHEMA

Syntax

The basic syntax of CREATE SCHEMA is as follows −

CREATE SCHEMA name;

Where name is the name of the schema.

Syntax to Create Table in Schema

The basic syntax to create table in schema is as follows −

CREATE TABLE myschema.mytable (
...
);

Example

Let us see an example for creating a schema. Connect to the database testdb and create a schema myschema as follows −

testdb=# create schema myschema;
CREATE SCHEMA

The message "CREATE SCHEMA" signifies that the schema is created successfully.

Now, let us create a table in the above schema as follows −

testdb=# create table myschema.company(
   ID   INT              NOT NULL,
   NAME VARCHAR (20)     NOT NULL,
   AGE  INT              NOT NULL,
   ADDRESS  CHAR (25),
   SALARY   DECIMAL (18, 2),
   PRIMARY KEY (ID)
);

This will create an empty table. You can verify the table created with the command given below −

testdb=# select * from myschema.company;

This would produce the following result −

 id | name | age | address | salary
----+------+-----+---------+--------
(0 rows)

Using Drop Schema

To drop a schema if it is empty (all objects in it have been dropped), use the command −

DROP SCHEMA myschema;

To drop a schema including all contained objects, use the command −

DROP SCHEMA myschema CASCADE;

Advantages of using a Schema

• It allows many users to use one database without interfering with each other.
• It organizes database objects into logical groups to make them more manageable.
• Third-party applications can be put into separate schemas so they do not collide with the names of other objects.