Drop a Query

# September 19, 2023

## How to escape a single quote in SQL Server?

Problem How to escape a single quote in SQL Server, with a solution that is also reproducible in MySQL? For example, let’s try to replace the single quote character with a hat (^) character. Input ID Name 1 John’s Pizza 2 Mary’s Cafe 3 Alice’s Diner Try Hands-On: Fiddle Create Input Table: Gist Desired Output …

## Sampling and Sampling Distributions – A Comprehensive Guide on Sampling and Sampling Distributions

Explore the fundamentals of sampling and sampling distributions in statistics. Dive deep into various sampling methods, from simple random to stratified, and uncover the significance of sampling distributions in detail. In this blog post we will learn What is Sampling? Why Sample? Types of Sampling Methods 3.1. Simple Random Sampling (SRS) 3.2. Stratified Sampling 3.3. …

## Law of Large Numbers – A Deep Dive into the World of Statistics

The Law of Large Numbers (LLN) is a fundamental theorem in probability and statistics, serving as the basis for many concepts and practices in the field. If you’ve ever heard the saying “the more the better,” you can think of LLN as the mathematical rendition of this proverb. In this blog post, we’ll dive into …

## What is the difference between INNER JOIN, OUTER JOIN and FULL OUTER JOIN?

Problem What is the difference between INNER JOIN, OUTER JOIN and FULL OUTER JOIN? Input Let’s create three example tables, employees, departments, and projects, and insert some sample data into them. SELECT * FROM EMPLOYEES; employee_id first_name last_name department_id 1 John Doe 1 2 Jane Smith 2 3 Bob Johnson 1 4 Alice Williams SELECT …

## How to select a random row using SQL?

Problem How to select a random row using SQL? Input employee_id first_name last_name salary 1 John Doe 50000 2 Jane Smith 60000 3 Michael Johnson 55000 4 Emily Brown 58000 5 David Davis 62000 Try Hands-On: Fiddle Create Input Table: Gist Desired Output employee_id first_name last_name salary 5 David Davis 62000 Solution 1: Using generated …

## How to randomly select rows from a large table in MySQL super fast?

Problem How to randomly select rows quickly from a large table in MySQL? Input employee_id first_name last_name department salary 1 John Doe HR 50000.00 2 Jane Smith Engineering 60000.00 3 Alice Johnson Finance 55000.00 4 Bob Brown Sales 52000.00 5 Eva Williams Marketing 48000.00 6 Chris Davis Engineering 62000.00 7 Sarah Wilson Finance 56000.00 8 …

## How to efficiently convert rows to columns in SQL?

Problem Given a table, how to efficiently convert rows to columns? So that, the records in a given row become column names and the values of the respective columns are taken from another column from the original table? Input employee_id skill_name skill_level 1 Java 4 1 SQL 3 1 Python 5 2 Java 3 2 …

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