HBase Vs Relational Databases

HBase	Relational Database
Does not have a fixed schema (schema-less). Defines only column families.	Has a fixed schema which describes the structure of the tables.
Works well with structured and semi-structured data.	Works well with structured data.
It can have de-normalized/sparse data (missing or NA values).	Can store only normalized data.
Built for wide tables that can be scaled horizontally.	Built for thin tables that is hard to scale.

HBase does not support SQL scripting; instead the equivalent is written in Java, employing similarity with a MapReduce application.

The Apache Phoenix project provides a SQL layer for HBase as well as JDBC driver that can be integrated with various analytics and business intelligence applications.

The Apache Trafodion projcect provides a SQL query engine with ODBC and JDBC drivers and distributed ACID transaction protection across multiple statements, tables and rows that use HBase as a storage engine.