SQL: Zero to Hero

Material Data Science
Dev Genius
Published in
7 min readSep 8, 2023

What is SQL?

SQL (Structured Query Language) is a domain-specific language used in programming and designed for managing data held in a relational database management system (RDBMS), or for stream processing in a relational data stream management system (RDSMS)

SQL Basics

SELECT

The SELECT DISTINCT statement is used to return only distinct (different) values.

Inside a table, a column often contains many duplicate values; and sometimes you only want to list the different (distinct) values.

SELECT DISTINCT * FROM TABLE_NAME;

OR

SELECT DISTINCT COLUMN1, COLUMN2, ….. FROM TABLE_NAME;

SELECT WITH NO DISTINCT

SELECT * FROM TABLE_NAME;

OR

SELECT COLUMN1, COLUMN2, …. FROM TABLE_NAME;

NOTE: The letter of “ * “ means to select all of columns and the code block in SQL must be ended with the letter of “ ; “.

NOTE2: You can write your code in upper and/or lower case.

No responses yet

What are your thoughts?