This tutorial provides an overview of the most commonly used SQL commands to create, alter, and manipulate tables and data in databases.
What Are SQL Commands?
SQL commands are standardized instructions used in Structured Query Language (SQL) to communicate with a relational database management system (RDBMS) and perform various tasks such as data manipulation, definition, and control. These commands allow you to create, modify, delete, and retrieve data from database tables and perform other database management operations.
Essential SQL Commands
Various SQL commands are available for managing databases, but some are essential and commonly used:
| SQL Command | Description |
|---|---|
| CREATE DATABASE | Initializes a new database. |
| CREATE TABLE | Constructs a new table within a database. |
| ALTER DATABASE | Alters the properties of an existing database. |
| ALTER TABLE | Modifies the structure of an existing table. |
| DROP TABLE | Removes a table and all its data. |
| INSERT INTO | Adds new records to a table. |
| SELECT | Fetches specific data from one or more tables. |
| UPDATE | Alters existing records in a table. |
| DELETE | Removes specified data from a table. |
SQL Command Execution Order
Understanding the sequence in which SQL commands are executed is crucial. Begin by creating a database, followed by tables within that database. Once your tables are set up, you can manipulate data by inserting, updating, or deleting. Finally, use the SELECT command to query and retrieve the data you need.