Important Categories of Structured Query Language (SQL)

Let us go through the most important categories of Structured Query Language. It is also known as SQL.

SQL - Structured Query Language

SQL have several categories of commands. But, the most important categories are nothing but to create tables, manipulate data in tables and read data from tables.

  • DDL - Data Definition Language
  • DML - Data Manipulation Language
  • DQL - Data Query Language

There are other categories as well, such as TCL where we have commands to commit or revert/rollback changes to the database objects.

DDL - Data Definition Language

Here is the DDL Command to create a table.

CREATE TABLE orders (
  order_id INTEGER,
  order_date DATE,
  order_customer_id INTEGER,
  order_status VARCHAR2(30)
);

DML - Data Manipulation Language

Here is the example to get data into a table.

INSERT INTO orders
VALUES (1, sysdate, 100, 'COMPLETE');

DQL - Data Query Language

Here is the command to query data from a table.

SELECT * FROM orders;
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