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31: 50+ SQL scenarios based interview Q&As – Finding records from first table where no match found in second table

Setup the data on db-fiddle MySQL V9.0 to practice. There are business scenarios for:

1) Finding records in the first table where matching records are found in the second table …



32: 50+ SQL scenarios based interview Q&As – use of unpivot, lag(..), row_num(..), cumulative sum() and CTE

Setup the data on db-fiddle MySQL V9.0 to practice. Make sure to select latest MySQL version to ensure Common Table Expressions (i.e CTE) is supported. This is not a real …



33: 50+ SQL scenarios based interview Q&As – Nuances of NULL in SQL

NULL is a special marker used in SQL to indicate that a data value does not exist in the database.

Setup the data on db-fiddle MySQL V9.0 to practice. Make …



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

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 …



Defining tables in postgresql with primary key, foreign key, unique constraint & data migration example

Uses DB-FIDDLE for the code example with PostgreSQL v17.

Q01 How will you go about defining tables with primary key, foreign keys and unique constraints?
A01 The main purpose of …



MySQL import and export of data via command line using mysqldump & mysql

Q01 How do you migrate MySQL database between two servers
A01 This can be done using an SQL Dump Export/Import.

1. Export MySQL Database to a dump File



SQL procedures vs functions with postgresql (i.e. plpgsql) examples

Q01 What is the difference between SQL stored Procedures & Functions?
A01 Stored procedure does not have a RETURNS clause, but you can use the OUT or INOUT parameter. …



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 …



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 …



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