DDL(Data Definition Language) Statements in PostgreSQL

Today we will show you basics of DDL Statements in PostgreSQL like Creating table, Editing a table, Truncating a table, Dropping a table, etc.

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First let’s understand what is DDL and then we will discuss about DDL Statements. So DDL is used to handle database description and schemas meaning it is used to modify or create the data structure.

There are four most used DDL Statements in PostgreSQL.

1. Create
2. Alter
3. Truncate
4. Drop

Create:-

Create statement is used to create table with their columns along with their data type. Below is the basic syntax to create a table.

Syntax:-

CREATE TABLE <table_name>(
<Column1> <DataType>,
<Column2> <DataType>
)

As you can see we have specify the table name after CREATE TABLE and then inside parenthesis Column name and it’s datatype. Below is the example of creating a table.

As you can see in the above example we are creating table Users.

Alter:-

Alter statement is used to modify the table structure like changing the data type of a column, changing name the of the column, renaming the column. Below is the syntax and example of adding a column.

Syntax:-

ALTER TABLE <table_name>

<ADD/DROP/ALTER/ALTER> COLUMN <column_name> <datatype>

Example:-

In the above example we are adding new column to Users table.

Truncate:-

Truncate is a part of DDL query as it affects the schema of the table. It is same in every SQL based RDBMS. We have detailed Article on Truncate and Delete.

Unknown facts about Truncate and Delete Statement

Syntax:-

TRUNCATE TABLE <table_name>;

Example:-

Drop:-

Drop statement is used to remove a table from the database, remove the database, etc. Below is the syntax and example of it.

Syntax:-

DROP TABLE <table_name/database_name>.

Example:-

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प्रकृत्यैव च कर्माणि क्रियमाणानि सर्वश: |
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