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Basic SQL Grammar

04 Nov 2018 Tags:
SQL, programming


SQL (to be Updated)

 

  • Structured Query Language (SQL), is a programming language used to manage or process data in Relational Database Management System (RDBMS)
  • SQL is useful in handling structured data that includes relations between different data tables
  • SQL is used to create, manage, query, manipulate the data with statements

    img source: https://medium.com/@swiftsnippets/database-system-s-rdbms-and-nosql-6afeef8168e5

     

Basic Statements

SELECT

  SELECT is used to select data from a database (most statements are self-explanatory…)

SELECT column1, column2, … FROM table_name;

 

If you want to select all columns, simply use * (asterisk)

SELECT * FROM table_name;

 

If you want to select only unique or different values, use DISTINCT

SELECT DISTINCT column1, column2, … FROM table_name;

 

If you want to select values with certain conditions, use WHERE

SELECT column1, column2, … FROM table_name WHERE condition;

The following are operations that can be used with the WHERE clause:

Operator Description
= equal
<> or != not equal
< less than
> greater than
BETWEEN between a range
LIKE pattern search
IN specify multiple values
as an inclusive syntax

   

Example

SELECT DISTINCT * FROM product_info WHERE price > 40;

       

AND, OR, NOT

  AND, OR, and NOT operators are combined with other statements to filter records in a more desirably way. It is used in a similar manner just as in other programming languages.

  • AND displays a record if all the conditions stated and connected with AND are TRUE
  • OR displays a record if any conditions stated with OR are TRUE
  • NOT displays a record if the conditions is NOT TRUE

 

Examples

SELECT * FROM product_info WHERE price BETWEEN 20 AND 30

SELECT * FROM product_info WHERE color = “red” OR “blue”

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