Dbms Mcq Multiple Alternative Questions

SQL uses Null to deal with missing data it supports three-valued logic and the rules governing SQL three-valued logic are shown beneath . The word NULL can additionally be a reserved keyword in SQL, used to identify the Null particular marker. Clauses, which are in some cases elective, constituent parts of statements and queries. This chart shows several of the SQL language elements that compose a single statement. Though MySQL’s relational nature and the following inflexible storage structures might sound restrictive, the tabular paradigm is perhaps probably the most intuitive, and finally permits for higher usability.


MongoDB stores knowledge as a JSON file; DynamoDB is a AWS product, usually lauded for its built-in safety and in-memory caching for sooner interactions. Relational databases offer nearly infinite number of attainable permutations to slice and manipulate the data, based on one’s wants, which turns out to be an enormous advantage in data evaluation. This includes CREATE (tables, views, objects, and so on.), ALTER and DROP . ADDRESSDELHIGURGAONROHTAKIf DISTINCT is not used, DELHI will be repeated twice in end result set. Before understanding GROUP BY and HAVING, we have to perceive aggregations capabilities in SQL.

Should I Study Python Earlier Than Sql?

The standard additionally describes mechanisms to ensure binary portability of SQLJ applications, and specifies numerous Java packages and their contained classes. The thought of Null was launched into SQL to deal with lacking information in the relational mannequin. The introduction of Null together with True and False is the inspiration of Three-Valued Logic. Null doesn’t have a value but is quite a placeholder or “mark” for missing information. Therefore comparisons with Null can by no means lead to both True or False but all the time within the third logical result, Unknown.

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