Introduction to PostgreSQL (Coding Style) Part-5

This blog aims to assist you in understanding the concepts of PostgreSQL with complete coding as query language.

PostgreSQL SQL commands

Note: Make sure you have Postgres installed on your system to proceed to this tutorial.

PostgreSQL - ALIAS Syntax

• In PostgreSQL, aliases can be used to temporarily rename tables or columns in queries.

• Table aliases allow you to refer to a table by a different name within a specific query, but the actual table name remains unchanged in the database.

• Column aliases are used to rename specific columns in query results, providing more meaningful or concise names for presentation without altering the underlying data.

Syntax Of Table Alias:

SELECT column1, column2....
FROM table_name AS alias_name
WHERE [condition];

Syntax Of Column Alias:

SELECT column_name AS alias_name
FROM table_name
WHERE [condition];

Example:

Consider the following two tables, (1) COMPANY table is as follows −

(2) DEPARTMENT as follows −

TABLE ALIAS

Note: Usage of TABLE ALIAS where we use C and D as aliases for COMPANY and DEPARTMENT tables, respectively −

Query:

SELECT C.ID, C.NAME, C.AGE, D.DEPT
FROM COMPANY AS C, DEPARTMENT AS D
WHERE C.ID = D.EMP_ID;

Result:

Column ALIAS

Note: The usage of COLUMN ALIAS where COMPANY_ID is an alias of ID column and COMPANY_NAME is an alias of name column −

Query:

SELECT C.ID AS COMPANY_ID, C.NAME AS COMPANY_NAME, C.AGE, D.DEPT
FROM COMPANY AS C, DEPARTMENT AS D
WHERE C.ID = D.EMP_ID;

Result:

I hope this blog has helped you understand the concepts of PostgreSQL with complete coding as a query language.

Check out a summary of Part-6.