SQL Clauses and Data Manipulation | Dataford Interview Questions

Explain DML, DCL, DDL commands in SQL

Asked in the Technical stage. Using PostgreSQL, explain the purpose of each command category and write a query that returns the supported command inventory for DDL, DML, and DCL.

Output

One row per command in the three requested categories.
Columns: command_category, command_name, and command_class.
Sort by category in DCL, DDL, DML order, then alphabetically by command name.

Schema

sql_command_categories

Column	Type	Description
category_idPK	INT	Identifier for a SQL command category
category_name	VARCHAR(20)	Name of the SQL command category

sql_commands

Column	Type	Description
command_idPK	INT	Identifier for a SQL command
category_id	INT	References the command category
command_name	VARCHAR(30)	SQL command keyword

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Problem