Stellar Information Technology Customer Service Executive Interview Questions and Answers

DDL stands for Data Definition Language and is used to define the structure of database objects. DML stands for Data Manipulation Language and is used to manipulate data within the database.

• DDL is used to create, modify, and delete database objects like tables, indexes, etc.

• DML is used to insert, update, delete, and retrieve data from tables.

• Examples of DDL statements include CREATE TABLE, ALTER TABLE, DROP TABLE.

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A subquery is a query nested within another query in SQL.

• A subquery is enclosed within parentheses and is used to return data that will be used by the main query.

• It can be used in SELECT, INSERT, UPDATE, and DELETE statements.

• Example: SELECT * FROM table1 WHERE column1 = (SELECT column2 FROM table2 WHERE condition);