SQL is the structured query language used to manage relational databases. It divides data into rows and columns, making it easy to retrieve information based on specific criteria. A primary key is a column or set of columns that uniquely identify each row in a table. It is used to maintain referential integrity between tables.

What is SQL?

SQL is a programming language that allows you to query and manipulate data within database management systems. It uses English-like statements to create tables, rename them, and select entries from rows in the tables. It also provides a way to connect these tables together using relationships.

A relationship is an association between two or more entities such as departments, workers, and projects. These relationships allow for the sharing of data between tables. This data can then be accessed and analyzed by the application.

As businesses move towards a digital world, they need to be able to analyze and access their information. This is where SQL comes in, and it's one of the most sought-after skills for data analysts. As such, interviews for these jobs often include a technical screening that tests candidates' SQL knowledge.

What are the basic syntax rules of SQL?

While there is no single SQL formatting standard, many experts agree on some general rules. For example, names for tables and columns should be short and easy to read. It is also a good idea to write comments in your code. This makes it easier for the interviewer to follow your logic and correct any mistakes.

SQL keywords are case-insensitive, but identifiers (table names, column names, etc) must be enclosed in quotation marks if they contain characters that are not allowed as part of an identifier or if the name is identical to a reserved keyword. SQL expressions frequently use lists and commas are used as list separators. sql interview questions and answers   supports functions and operators commonly found in other computer languages, such as plus/minus, division, multiplication, or, and shift-high/shift-low (like C). The ORDER BY and GROUP BY clauses are similar to those in the C language.

What are the basic operators of SQL?

SQL contains a wide variety of logical operators. These allow you to filter data based on multiple conditions. For example, the LIKE operator allows you to match values ​​based on their similarities, while the IN and BETWEEN operators allow you to select rows that meet certain criteria.

These logical operators are commonly used in the WHERE clause of an SQL query. However, they can also be useful in other places, such as the HAVING clause and joins. Be sure to familiarize yourself with the different types of logical operators in SQL before your interview. Also, be sure to include written comments in your code — this can help the interviewer understand your solution and will save time during the screening process.

What are the subsets of SQL?

Subsets of SQL are the pillars of the structured query language and are responsible for the successful manipulation of data. The SELECT statement in particular, along with its various clauses such as WHERE, GROUP BY, and HAVING, are important subsets of SQL.

These statements allow users to retrieve particular data from a database. They also help in sorting, filtering, and grouping data so that it is easier for users to examine and understand. These days, it is common for coding interviews to include a whiteboard screening test in which candidates must write their queries by hand. This is so that interviewers can see that the candidate has a grasp of SQL concepts and can problem solve. In addition, this technique helps interviewers evaluate the candidate's ability to work on real-world problems.

What are the syntax rules of SQL?

SQL is a programming language that uses specific rules for combining and formatting tokens to create statements and queries. These rules help ensure that the SQL code is easy to read and understand. They also help to prevent errors when making changes to the code. While many SQL programmers have their own style and preferences when writing SQL code, following these standards is recommended by experts.

SQL statements must always start with a keyword or identifier, such as SELECT, FROM, and WHERE. The statement must then be followed by one or more clauses, which describe what you want to do with the data. Each clause must be separated by a semicolon. Identifiers should be written in lowercase, and names of tables and columns should be separated by an underscore (_) or camelCase (eg EmployeeCity).