Are you an aspiring individual who seeks to pursue a career in the IT field?

 If Yes, then learning about SQL can benefit you significantly. It adds to your arsenal and ensures that you secure a reputed post.

Therefore, if you lack knowledge about this concept then this blog is for you as we address the fundamental aspects related to SQL.

What is SQL and why is it important? 

Structured Query Language or SQL is a language that facilitates access and manipulation of databases. It manages and stores data in various tabular formats. The SQL statements update and retrieve data of a specific database. Dynamic SQL is a programming technique that enables programmers to build the SQL

While appearing for job interviews, Dynamic programming interview questions and SQL interview questions are very important and must be practiced thoroughly. 

In 1986, SQL was declared as a standard of ANSI or American National Standards Institute. It also became a standard of the International Organization for Standardization or ISO in the year 1987.

In order to learn and master the skill of the structured query languages, one needs to practice over and over again. Here are a few tips for practicing and mastering the Structures Query Languages.

Essential Questions about SQL

In this article we will be discussing 10 sample SQL problems and solutions. questions are from concepts like basic retrieval, formatting, aggregation, etc.

  1. Given a specific table, find the duplicate row count.

These questions have the most realistic applications since there are a lot of times when one would need to find the duplicate row count of a table. 

To solve this question, the count function needs to be used. You will also have to use order by clause.

 

  1. From a given table, find the residents whose name starts with R and the surname with M. 

 

For this question it is best to use the most common wildcard to retrieve data with specific conditions mentioned. This method is called the SQL like special character.

  1. Find the manager and employee names from the given table.

In questions like these where specific names need to be identified, you will need to use a self join method to retrieve the requested records from the said table. 

  1. Explain the query for displaying even records from a specific resident table.

In this question you will be using a combination of the rownum and mod functions so as to retrieve the even records.  

  1. By using a single query, verify if the said email is correct or not. 

This is a very commonly used operation where you need to verify something. To solve this question, you will need to apply the regular expression functions in order to verify the email validation. 

  1. From a table of salary for some teachers, how will you find the maximum and minimum salaries?

Even though the question seems a bit tricky since 2 aggregate functions cannot be used at a time, solving this one is actually very easy. The union set operator from the SQL set operators will need to be used here.

  1. What is the procedure of retrieving the last record from a said table?

This question is also very common. The tables store the records according to specific row IDs provided for each record. Hence, you will need to find the maximum row ID record. 

  1. Let us say you are given a list of resident members of a society from the year 2006 to current date. How will you find the residents who were added after the year 2012?

In order to solve this question, you will have to use the To_Char function to be able to retrieve the specified data based on the initial or joining date.

  1. If you are given a table of citizens living in a particular part of a city. How will you find the odd records from the table?

To display the odd records from the said table, you will use the Rownum and mod functions and retrieve the requested records. 

  1. How will you represent the following structure with just one query?

#

##

### 

This question requires the Ipad() function in order to retrieve the symbol. Not that here, we cannot use a dual table.

Tips that will help you to solve SQL problems effectively.

The first and the most important thing while learning SQL is to know that you will need a lot of practice and rehearsing. Here are a few more things to keep in mind while attempting these question sets.

Operations that can be performed with SQL

  • You can retrieve and update the data records in any database.
  • You can create a new database.
  • You can create new tables.
  • You can insert new records in a database.
  • You can delete any records or tables from a database.
  • You can create various views in an existing database.

System Incorporation

In order to incorporate a system in your website that will help you display data from a specific database, you will need the following things:

  • Using SQL to fetch the requested data.
  • Using HTML or CSS to help with the styling of the page.
  • A RDBMS database like the SQL server, MS access, etc. 
  • Using PHP or ASP which are server-side scripting languages.

Basic Concepts

Here are a few basic important concepts that one must know while learning the Structures Query Language:

  • Three keys of SQL namely, the Primary key, Foreign Key, and the Unique Key.
  • Relational databases.
  • Types of views in SQL.
  • SQL transactions.
  • Subqueries related to SQL.
  • Various cloning tables included in SQL.
  • Temporary tables.
  • Database normalizations, and some others. 

Basic SQL Commands

  • There are some basic commands in SQL that one must be aware of:
  • Create table: creating a new table in an existing database.
  • Create database: creating a new database altogether.
  • Alter database: helps you modify a database as desired
  • Insert: helps to insert new information in an existing database.
  • Select: retrieves or fetches data from an existing database.
  • Update: helps in updating the existing information of a database.

Conclusion:

These were some sample questions and their explanations related to the SQL problems and solutions. Practicing these questions along with the dynamic programming interview questions can be very helpful while appearing for interview tests and technical rounds.