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Tables

A table in relational database consists of rows and columns.

  • Columns are fixed in order and each column has a unique name within a table.
  • Rows can be unlimited but SQL does not guarantee the order in which rows are returned, unless you explicitly mention a sorting parameter like order by.
  • Each column has a data type associated with it. This restricts the type of data that a column can store. For example, a column with data type integer will not accept string inputs. We will read more about data types in the next section.

Creating a table in PostgreSQL

Let us look at an example of creating a table in PostgreSQL.

CREATE TABLE author (
id integer,
name text
);

The above statement creates a table named author with two columns id and name.

The id column has the data type integer and name column has the data type text.

Dropping a table in PostgreSQL

DROP TABLE author;

This will delete the table author from the public schema.

And if you want to cascade delete all associated objects, you can make use of the following:

DROP TABLE author CASCADE;

We will look at use cases of CASCADE when we look at relationships and foreign key constraints.

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