SQL Syntax sheet

Important SQL Commands

SELECT

• Extracts data from a database Syntax like so:

  SELECT column1, column2, ...
  FROM table_name;

• To select all columns from a table: SELECT * FROM table_name
• The SELECT DISTINCT statement is used to return only distinct (different) values: SELECT DISTINCT Country FROM Customers;

WHERE

This clause is used to filter records. It is used to extract only those records that fulfill a specified condition. Example:

SELECT * FROM Customers
WHERE Name="Bob";

UPDATE

Updates data in a database. Syntax example:

UPDATE table_name
SET column1 = value1,
		column2 = value2, ...
WHERE condition;

More commands

• DELETE - deletes data from a database
• INSERT INTO - inserts new data into a database
• CREATE DATABASE - creates a new database
• ALTER DATABASE - modifies a database
• CREATE TABLE - creates a new table
• ALTER TABLE - modifies a table
• DROP TABLE - deletes a table
• CREATE INDEX - creates an index (search key)
• DROP INDEX - deletes an index