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00: 18+ SQL best practices interview Q&As

It is a must to know the order in which the SQL clauses are executed. This is demonstrated with an example below in #5. Have this order of execution visibly pinned and understood. SQL is very easy to learn, but lots of hands-on experience is required to master:

1) to translate business requirements into SQL.
2) to write efficient & maintainable queries.
3) to break-down & reverse engineer complex SQL queries into business requirements to enhance or modify.

Let’s start with the best practices.

#1. Use uppercase for the keywords like SELECT, FROM, JOIN, GROUP BY, WHERE, etc. It’s …

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00: 25+ SQL interview questions & answers – beginner

SQL interview Questions & Answers is a must for any developer as all non-trivial applications need to talk to a database with CRUD operations. Q3 – Q15 are very popular with the interviewers.

If you want to quickly practice your SQL skills try DB Fiddle or install MySQL locally as shown in the MySQL database getting started.

Q1. Can you explain DDL statements in regards to SQL?
A1. DDL stands for Data Definition Language, which are statements used to define the database structure or schema. CREATE – to create objects in the database, ALTER – alters the structure of …

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00: 25+ SQL interview questions & answers – intermediate to experienced

This continues 25+ SQL interview questions & answers – beginner Q16. Why do you have CASE statements in SQL? A16. CASE statements in SQL are similar to IF and ELSE conditions in programming languages. CASE statements are used to fetch particular values based on certain conditions.



01: 50+ SQL scenarios based interview Q&As on identifying & deleting duplicate records

50+ SQL interview questions and answers to solve real business scenarios. SQL is widely used in building microservices & Big Data projects. Learning SQL syntax is easy, but being able to convert a given business requirement into a query takes lots of practice. These scenarios based interview questions can assesses your experience.

Considerations & Tips

It is important to first understand the problem statement, and then ask the right questions to solve the problem.

1) Break down a complex business requirement into sub sections.

2) Think about the grain of the data. For example, account level, user level, department level, …

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02: 50+ SQL scenarios based interview Q&As on joins, CDC and recursive CTE

This extends 50+ SQL scenarios based interview questions answered on identifying & deleting duplicate records. You practice these in SQLs by setting up the data on db-fiddle MySQL V8.0 or a database server & SQL client of your choice. Q01 When you have a table that maintains history of record…



15+ SQL optimisation interview questions & answers with scenarios

1) Select fields instead of using SELECT *. The “*” is used as a short hand to query all available data from a table. If a table has many fields and rows, this takes database resources by querying a lot of unnecessary data. Inefficient:

Efficient:

2) Avoid SELECT…



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