Difference Between SQL and HQL (with Table)

Data is a collection of unprocessed factual information or statistics in any form over a network. Processing data turns it into information which then is of significant use. Related data is organized into databases (both hardware and software) for easy management. DBMS(Database Management System) is a software that allows the user to create and manipulate databases.

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SQL vs HQL

The main difference between SQL and HQL is that SQL directly works on databases through queries whereas HQL operates on objects and their properties which is then translated into conventional queries to run databases.

To request and extract data from a database by sending queries, we use QL (Query Language). SQL (Structured Query Language) and HQL (Hibernate Query Language) are used to retrieve data from RDBMS (Relational DBMS) that stores data in tabular form.

In our day-to-day life query languages play a vital role in providing the basis for various interfaces like the ATM, web pages, online order processing, accounting, insurance records, etc.

Comparison Table Between SQL and HQL

Parameter of Comparison

SQL

HQL

Full-Form

Stands for Structured Query Language

Stands for Hibernate Query Language

Type of programming language

Traditional query language

JAVA based OOP query language

Concerns

It pertains to the relation between two tables or columns

It pertains two the relation between two objects

User-friendliness

Offers complex interface to new users

Provides user-friendly interface

Features

Uses tables and columns

Uses JAVA classes and variables

Interaction with database

Directly interacts with the database

Uses the ‘Hibernate’ interface to interact with the database

Speed

Native SQL is usually faster

Non-native HQL is usually slower since its runtime is based o mapping, but its speed can be increased by setting the right cache size of the query plan

What is SQL?

SQL often referred to as ‘sequel’ or ‘S.Q.L’,  is a database query language that is used to process data from RDBMSs. SQL is not an OOP (Object-oriented programming language), rather, it directly generates queries and sends requests for data retrieval from RDBMs. It operates on tables and columns where the data is stored and handles all operations in RDBMSs.

It is used as the standard database query language in almost all RDBMSs like MySql, Oracle, MsAccess, etc. The standard SQL commands that are used to interact with the relational databases are SELECT, CREATE, DELETE, INSERT, UPDATE, and DROP.

Unlike other programming languages, SQL cannot be used to develop stand alone programs and can be operated only inside RDBMSs. It is a declarative type of language, i.e. it tells the database what needs to be done and lets the RDBMS decide the details of implementation (how it needs to be done)

Its advantage is that the user is not required to write substantial amount of codes, but the users have only partial control over the databases due to the hidden business rules, and it also has a quite complex interface.

What is HQL?

HQL or Hibernate Query Language is an object-oriented query programming language which is written embedded in JAVA code and uses various functions under the JAVA library to convert the entity codes into traditional query codes that can interact with the databases.

This function of conversion is performed by a JAVA framework called ‘Hibernate’ from where HQL derives its name. The meaning of hibernate is to pass a particular time period in resting/inactive state. Similarly, the ‘hibernate’ feature remains active only behind the application.

It is an ORM (Object Relational Mapping) based framework that transfers data between an application and a relational database in the form of objects. HQL works with classes and their properties which is finally mapped to the table structure inside the corresponding database.

HQL is very useful if a programmer knows OOP language and wishes to interact with databases, wherein she/he can do so without learning the traditional query language SQL.

Despite the fact that HQL is very user-friendly, it is usually slower than SQL as its runtime is based on mapping. Also, it is not suitable for small projects which involve less number of tables since introducing the entire hibernate framework becomes difficult.

Main Differences Between SQL and HQL

  1. SQL is a traditional query language that directly interacts with RDBMs whereas HQL is a JAVA-based OOP language that uses the Hibernate interface to convert the OOP code into query statements and then interacts with databases.
  2. SQL is solely based on RDBMSs but HQL is a combination of OOP with relational databases.
  3. SQL is concerned with the relation between two tables or columns while HQL is concerned with the relation between two objects.
  4. A user who doesn’t know QL but has idea about OOP language like JAVA can interact with databases using HQL but not SQL.
  5. SQL doesn’t support OOP features like polymorphism, inheritance, and association, but HQL does.
  6. SQL has a complex interface as compared to the user-friendly OOP interface on which HQL is based.
  7. Both SQL and HQL use the same set of keywords but SQL uses tables and columns in contrast to HQL which uses JAVA classes and properties.
  8. Traditional SQL code is longer than the HQL code.
  9. SQL is usually faster than the non-native HQL, however, by setting the correct cache size of the query plan, HQL can be made to operate as fast as SQL.

Conclusion

The main purpose of SQL and HQL, or rather any query language is to allow the user to extract data from databases and information systems.

SQL is different from other programming languages in the sense that it only works inside a database management system and cannot create stand-alone programs whereas this is not the case with HQL.

A user who is new to QL and wishes to interact with RDBMSs and get exposure to a native query language must preferably opt for SQL since it is traditional and fast. On the other hand, a user who has a coding background in an OOP language must go for HQL, since it has a more user-friendly interface with OOP features.

References

  1. https://books.google.co.in/books?hl=en&lr=&id=HblnED6bKUgC&oi=fnd&pg=PR25&dq=sql+tutorial+informix+guide&ots=scXEV5CJcB&sig=6QyVATrORJKnQ2Fo0L9xBF62SRM&redir_esc=y#v=onepage&q&f=false
  2. https://books.google.co.in/books?id=n8kFAwAAQBAJ&pg=PA2&dq=hql+tutorial&hl=en&newbks=1&newbks_redir=1&sa=X&ved=2ahUKEwjUlfbE0tfsAhX6wzgGHepLDeAQ6AEwAnoECAIQAg#v=onepage&q=hql%20tutorial&f=false

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