What is SQL
What is SQL
SQL, or Structured Query Language, is a programming language that manages and manipulates relational databases. It performs tasks such as querying data, updating records, inserting data, and deleting data in a relational database management system (RDBMS).
Structured query language helps data move between databases and apps, playing a key role in today's software setup. Let's try to grasp the concept of communication between databases and applications through an illustration.
This diagram illustrates a multi-directional flow of data and actions between the client, server, and database.
SQL Commands
SQL provides a standardized way to interact with and manage databases. You can communicate with the database using the specific keywords and commands.
SQL commands are essential for managing and querying relational databases. Each command serves a specific purpose in manipulating and retrieving data from the database
SQL instructions are classified into five types: DDL, DML, DCL, TCL, and DQL.
1. Data Definition Language (DDL)
DDL is used for defining and managing the structure of the database, such as creating, altering, and deleting tables and defining constraints.
2. Data Manipulation Language (DML)
DML is used for manipulating data stored in the database, such as inserting, updating, and deleting records.
3. Data Query Language (DQL)
DQL is used to fetch the data from the database.
4. Data Control Language (DCL)
DCL is used for managing access to data within the database, controlling user privileges, and ensuring data security.
5. Transaction Control Language (TCL)
TCL commands are used to grant and take back authority from any database user.
This was a brief overview of all SQL commands. In later parts, we will examine each of these in further detail, along with their detailed instructions. In the remaining chapters, we will assume MySQL syntax for all SQL queries.
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