SQL DML Explained: SELECT, INSERT, UPDATE and DELETE Commands

Data Manipulation Language (DML) is the set of SQL commands used daily to query, insert, update, and delete data within a database schema. The SELECT command is the most widely used, supporting clauses like WHERE, JOIN, GROUP BY, HAVING, and ORDER BY to filter, combine, and sort data. INSERT allows adding one or multiple records to a table at once, while UPDATE modifies existing rows — always requiring a WHERE clause to avoid altering every record unintentionally. DELETE removes specific rows and, unlike TRUNCATE, processes data line by line, supports triggers, and can be rolled back within a transaction. This makes DELETE safer but slower than TRUNCATE when handling large volumes of data.