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10: Getting started with MySQL database beginner tutorial

All Java developers not only must know “SQL”, but also a database is required for “JDBC tutorials”, “Hibernate Tutorials”, and so on. Any decent Java application will require a database. So, …



14+ SQL beginner interview Q&As

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 …



15 Database design interview Q&As

Q1. What is normalization? When to denormalize? A1. Normalization is a design technique that is widely used as a guide in designing relational databases. Normalization is essentially a two step process …



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 …



15+ SQL scenarios based interview questions answered

Q1 How will you go about identifying duplicate records in a table?
A1 The following SQL query will do the trick.



Auditing database record changes in Oracle

Q. What are some of the considerations in auditing database table data? A. Creating audit tables without any constraints to store record changes.  Audit tables are heavily hit with inserts, hence …



Common Table Expressions (i.e. CTE) in SQL using the “WITH” clause

Common Table Expressions or CTE’s for short are used in SQL to simplify complex joins and subqueries, and to provide a means to query hierarchical data such as an organisational chart. …



Deleting records in SQL Interview Questions and Answers

The following is a very popular SQL job interview question. Q. What is the difference between “Truncate” and “Delete” commands? A.  TRUNCATE TABLE_NAME always locks the table and page but not …



SQL analytic functions interview questions – Part 1

Data Engineers & analysts must know the analytic functions applied over a window of rows is a powerful tool to analyse the data. This post compliments “Apache Spark window functions



SQL analytic functions interview questions – Part 2

This extends SQL window function for analytical queries interview questions – Part 1 Analytic function construct



SQL analytic functions interview questions – Part 3

This extends SQL analytic functions interview questions – Part 2 and SQL analytic functions interview questions – Part 1. The below example was created in IMPALA SQL engine with Common Table …



SQL querying Temporal tables & SCD Type 2

Q1. What is a temporal table? A1. Temporal tables store and maintain information with respect to time. This tracks data changes, and enables us to maintain and manage the history of …



SQL retrieving the latest records interview Q&As

This question can reveal a lot about your ability to write SQL queries as different approaches can be used and there will be drill down on pros and cons of each …



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