Question

Database Management

Discuss the key differences between QBE, DDL, and DML and also note issues that could occur in a database if data integrity is not forced when utilizing DDL and DML.

Answer 1

Query By Example(QBE) is a feature which is added in relational database that provides user friendly interface to execute the queries. It is a graphical query language where a user who don't know proper syntax can also write queries. Only some fields are required to fill and you will get output.

DDL (data definition language) is used to create , add constraints and alter the structure of database. example:- create, alter etc. It works on structure of tables. These commands are auto commit. It can't be rollback.

DML(data manipulation langauge) is used to insert , update , delete the records . It works on data of tables. You need to manually commit . It is possible to get data back before the last commit operation.

When integrity is not forced then you may get invalid output. suppose entity integrity is not inforced, then you will receive redundant records.

When referential integrity is not inforced, you tables which are linked are not secure.

DON'T FORGET TO HIT LIKE.

THANKS BY HEART.