PostgreSQL Arrays: Creating, Indexing & Querying with Real Examples
PostgreSQL Arrays: Complete Guide to Array Types PostgreSQL arrays store multiple values in a single column. …
7 min ReadAll of Vaibhav Choudhari's tutorials
PostgreSQL Authentication: How pg_hba.conf Controls Database Access
PostgreSQL Authentication: How pg_hba.conf Controls Database Access Before a user can connect to PostgreSQL, the server …
8 min Read
PostgreSQL Complex JOIN Conditions: Non-Equi Joins & Advanced Patterns
PostgreSQL Complex JOIN Conditions: Beyond Simple Equality Most JOINs use simple equality: ON table1.id = table2.id. But …
10 min Read
PostgreSQL Data Types: Numeric, String, Date, JSON & Array Types Complete Reference
PostgreSQL Data Types: Complete Reference Guide Every database column needs a data type. You might think this is just a …
17 min Read
PostgreSQL Database Triggers: Complete Guide to BEFORE, AFTER & Events
PostgreSQL Database Triggers: Complete Guide Triggers automatically execute when data changes. They’re powerful …
9 min Read
PostgreSQL Date Functions & Formatting: Complete Reference
PostgreSQL Date Functions & Formatting: Complete Guide Working with dates requires specific functions - extracting …
8 min Read
PostgreSQL DISTINCT and GROUP BY: Remove Duplicates & Summarize Data
PostgreSQL DISTINCT and GROUP BY: Remove Duplicates & Summarize Data Sometimes you don’t want individual …
8 min Read
PostgreSQL Error Handling: EXCEPTION Blocks & RAISE in PL/pgSQL
PostgreSQL Error Handling: EXCEPTION Blocks & RAISE Functions fail sometimes - queries return no data, constraints …
10 min Read
PostgreSQL INNER JOIN Examples: From Basic to Advanced Patterns
PostgreSQL INNER JOIN Examples: From Basic to Advanced INNER JOINs are the most common join type. They return only …
10 min Read
PostgreSQL Installation Guide: Complete Setup for Windows, Mac & Linux
PostgreSQL Installation Guide: Complete Setup for Windows, Mac & Linux Getting PostgreSQL up and running on your …
12 min Read
PostgreSQL JOINs: Complete Guide to INNER, LEFT, RIGHT & FULL OUTER Joins
PostgreSQL JOINs: INNER, LEFT, RIGHT, FULL with Real Examples JOINs are how you combine data from multiple tables. …
8 min Read
PostgreSQL JSON Functions & Operators: Complete Guide with Real Examples
PostgreSQL JSON Functions & Operators: Complete Guide PostgreSQL’s JSON and JSONB support is powerful but has …
8 min Read
PostgreSQL LEFT JOIN vs RIGHT JOIN: Complete Guide with Examples
PostgreSQL LEFT JOIN vs RIGHT JOIN: Complete Guide LEFT and RIGHT JOINs are outer joins - they keep all rows from one …
10 min Read
PostgreSQL LIMIT and OFFSET: Pagination Techniques & Best Practices
PostgreSQL LIMIT and OFFSET: Pagination Techniques & Best Practices LIMIT retrieves a specific number of rows. …
7 min Read
PostgreSQL Multiple JOINs: Chaining Tables with Performance Tips
PostgreSQL Multiple JOINs: Chaining 3+ Tables Together Real-world databases require joining more than two tables. You …
11 min Read
PostgreSQL PL/pgSQL Functions: Syntax, Variables & Control Flow
PostgreSQL PL/pgSQL Functions: Complete Syntax Guide PL/pgSQL is PostgreSQL’s procedural language. It adds …
9 min Read
PostgreSQL SELECT Statement: Complete Guide with WHERE, ORDER BY & LIMIT
PostgreSQL SELECT Statement: Complete Guide with WHERE, ORDER BY & LIMIT The SELECT statement is the foundation of …
13 min Read
PostgreSQL Stored Procedures, Functions & Triggers: Complete Guide
PostgreSQL Stored Procedures, Functions & Triggers: Complete Guide Database logic doesn’t always belong in …
10 min Read
PostgreSQL Subqueries: Nested SELECT Statements for Complex Logic
PostgreSQL Subqueries: Nested SELECT Statements for Complex Logic A subquery (or inner query) is a SELECT statement …
8 min Read
PostgreSQL Users & Roles: Creating and Managing Database Access
PostgreSQL Users & Roles: Creating and Managing Database Access In PostgreSQL, “users” and …
9 min Read
PostgreSQL UUID vs SERIAL: Choosing the Right Primary Key Strategy
PostgreSQL UUID vs SERIAL: Choosing the Right Primary Key One of the first decisions you make when designing a table is: …
9 min Read
PostgreSQL WHERE Clause: Advanced Filtering with Operators & Logic
PostgreSQL WHERE Clause: Advanced Filtering & Pattern Matching The WHERE clause is where you ask specific questions …
8 min Read
PostgreSQL: Absolute Value - Get Positive Numbers
PostgreSQL: Absolute Value In my work building financial dashboards and inventory systems, I constantly need to measure …
7 min Read
PostgreSQL: Add Hours to Timestamp - Time Interval Arithmetic
PostgreSQL: Add Hours to Timestamp You need to calculate future times by adding hours. Maybe you’re scheduling …
4 min Read
PostgreSQL: Add Minutes to Timestamp - Minute-Level Time Arithmetic
PostgreSQL: Add Minutes to Timestamp When you’re building scheduling systems, setting cache expiration times, or …
4 min Read
PostgreSQL: Calculate Age in Days - Days Between Dates
PostgreSQL: Calculate Age in Days I constantly need to know “how old is this?” Whether it’s how many …
4 min Read
PostgreSQL: Calculate Business Days Between Dates
PostgreSQL: Calculate Business Days Between Dates When you’re tracking SLAs, estimating project timelines, or …
3 min Read
PostgreSQL: CASE WHEN Multiple Conditions - Conditional Logic
PostgreSQL: CASE WHEN Multiple Conditions I remember the first time I tried to classify employees into job levels based …
8 min Read
PostgreSQL: Cast JSONB to Integer - Convert JSON Number Type
PostgreSQL: Cast JSONB to Integer You’ve got numeric data stored inside JSONB objects, and you need to treat it as …
5 min Read
PostgreSQL: Cast VARCHAR to Boolean - String to Bool Conversion
PostgreSQL: Cast VARCHAR to Boolean I’ve dealt with legacy systems that store boolean flags as …
2 min Read
PostgreSQL: Change String Case - Uppercase Lowercase Conversion
PostgreSQL: Change String Case I’ve dealt with enough inconsistent data to know that case matters more than …
7 min Read
PostgreSQL: Check If Array Contains NULL
PostgreSQL: Check If Array Contains NULL Working with arrays, you sometimes need to know: “Does this array have …
2 min Read
PostgreSQL: Check If String Is Date - Validate Date Format
PostgreSQL: Check If String Is Date When you’re importing messy data, you need to know which rows have valid dates …
2 min Read
PostgreSQL: Combine Date and Time into Timestamp
PostgreSQL: Combine Date and Time into Timestamp I’ve worked with systems where DATE and TIME are stored …
6 min Read
PostgreSQL: Compare JSON Arrays - Check Array Equality
PostgreSQL: Compare JSON Arrays When you’re working with JSON data that contains arrays—like skill sets for …
3 min Read
PostgreSQL: Convert Date to Unix Timestamp - Epoch Conversion
PostgreSQL: Convert Date to Unix Timestamp You need to work with Unix timestamps — the number of seconds since January …
4 min Read
PostgreSQL: Convert Integer to Decimal - Precise Numeric Conversion
PostgreSQL: Convert Integer to Decimal You need to convert integer values to decimals for precise calculations, …
3 min Read
PostgreSQL: Convert Text to Date - Parse String to Date Type
PostgreSQL: Convert Text to Date When you’re importing data from CSV files, APIs, or external systems, dates …
2 min Read
PostgreSQL: Extract JSON Path - Navigate JSON Hierarchy
PostgreSQL: Extract JSON Path Working with API responses, configuration data, or semi-structured information, …
2 min Read
PostgreSQL: Fill Missing Dates - Time Series Completion
PostgreSQL: Fill Missing Dates When you’re analyzing time series data—sales by day, events by hour, user activity …
2 min Read
PostgreSQL: Filter by JSONB Field - Query JSON Data
PostgreSQL: Filter by JSONB Field If you’re storing data as JSONB in PostgreSQL and need to filter rows based on …
5 min Read
PostgreSQL: Find Last Occurrence of Character - Last Position
PostgreSQL: Find Last Occurrence of Character I’ve spent more time than I’d like to admit trying to extract …
7 min Read
PostgreSQL: Find Position of Element in Array
PostgreSQL: Find Position of Element in Array When you’re working with arrays in PostgreSQL, you often need to …
4 min Read
PostgreSQL: Flatten Nested Arrays - Convert Multidimensional to Single
PostgreSQL: Flatten Nested Arrays I’ve encountered data structures where arrays are nested inside arrays—maybe a …
1 min Read
PostgreSQL: Format Number - Display Numbers Nicely
PostgreSQL: Format Number If you’ve ever had to display financial data to customers or executives, you know that …
7 min Read
PostgreSQL: Generate Random String - Create Random Strings
PostgreSQL: Generate Random String I’ve built systems that need to generate random tokens for user verification, …
3 min Read
PostgreSQL: Get Distinct Array Elements - Remove Duplicates
PostgreSQL: Get Distinct Array Elements I’ve worked with systems where arrays accumulate duplicates—maybe a …
4 min Read
PostgreSQL: Get Week Start Date - First Day of Week
PostgreSQL: Get Week Start Date When I’m building reports that group data by week, or when I need to find the …
2 min Read
PostgreSQL: GREATEST and LEAST Functions - Min/Max of Values
PostgreSQL: GREATEST and LEAST Functions When I’m building commission calculations, handling multiple price lists, …
7 min Read
PostgreSQL: Merge JSON Objects - Combine JSONB Objects
PostgreSQL: Merge JSON Objects When you’re working with configuration data, user profiles, or any system that …
2 min Read
PostgreSQL: Remove Last Character from String
PostgreSQL: Remove Last Character from String You’ve got messy data with trailing characters you don’t need. …
5 min Read
PostgreSQL: Remove Specific Characters from String
PostgreSQL: Remove Specific Characters from String Remove specific unwanted characters like dashes, brackets, or special …
3 min Read
PostgreSQL: Round Decimal - Round Numbers to Specific Places
PostgreSQL: Round Decimal If you’ve ever worked with financial data, pricing, or any calculation involving …
6 min Read
PostgreSQL: Select Every Nth Row - Complete Guide
PostgreSQL: Select Every Nth Row When you’re working with large datasets, sometimes you need to sample data—taking …
3 min Read
PostgreSQL: Slice Array - Get Subset of Array Elements
PostgreSQL: Slice Array Extract a subset of elements from an array using slicing syntax. Problem Array: {Python, SQL, …
2 min Read
PostgreSQL: String Concatenation - Combine Strings
PostgreSQL: String Concatenation I’ve spent countless hours building user-facing reports, email templates, and …
9 min Read
PostgreSQL: Subtract Hours from Timestamp - Go Back in Time
PostgreSQL: Subtract Hours from Timestamp I frequently need to look back in time—finding events from the past 24 hours, …
2 min Read
PostgreSQL: Sum Array Column - Add All Array Elements
PostgreSQL: Sum Array Column When you store related numeric values in an array—like multiple sales amounts for an …
2 min Read
PostgreSQL: Trim Whitespace from Strings - Remove Leading/Trailing Spaces
PostgreSQL: Trim Whitespace from Strings If you’ve ever imported data from CSV files, spreadsheets, or external …
8 min Read
PostgreSQL: Truncate Decimal - Remove Decimal Places
PostgreSQL: Truncate Decimal I’ve run into scenarios where I need to be conservative with numbers—always rounding …
6 min Read
psql Command Reference: Essential PostgreSQL Command-Line Commands
psql Command Reference: Essential PostgreSQL Command-Line Commands The psql command-line tool is your primary way to …
9 min Read
Data Visualization in R - Complete Guide
Introduction A picture is worth a thousand words. In data analysis, this is absolutely true. A well-designed …
12 min Read
Descriptive Statistics in R - Complete Guide
Descriptive statistics form the foundation of data analysis, providing summary measures that describe the main features …
12 min Read
R Built-in Datasets - Complete Reference Guide
R comes with built-in datasets that are invaluable for learning, teaching, and prototyping data analysis techniques. …
8 min Read
R Data Frames - Complete Guide
Data frames are absolutely central to R programming. In my work analyzing real datasets, I’d say I spend 80% of my …
13 min Read
R Data Import/Export - Master Guide
Importing and exporting data is one of the first and most important tasks in data analysis. Whether you’re working …
8 min Read
R Data Transformation - Ultimate Guide
Data transformation is one of the most critical skills you’ll develop as an R programmer. In my experience working …
12 min Read
R Distance Metrics - Complete Reference
Distance and similarity metrics are fundamental tools in machine learning, clustering, and data analysis. They measure …
8 min Read
R File & System Operations - Complete Guide
File and system operations are essential for data analysis workflows, allowing you to manage input/output files, …
6 min Read
R Functions & Control Flow - Complete Guide
Functions and control flow are the backbone of R programming. They enable you to write reusable, organized code and …
8 min Read
R Hypothesis Testing - Complete Guide
Hypothesis testing is the foundation of statistical inference. It allows you to make decisions about populations based …
6 min Read
R Matrices & Linear Algebra - Complete Guide
Matrices are the backbone of statistical computing. Whether you’re aware of it or not, every time you fit a linear …
11 min Read
R Probability & Combinatorics - Complete Guide
Probability and combinatorics are foundational to statistics, data science, and machine learning. Whether you’re …
8 min Read
R Regular Expressions - Complete Guide
Regular expressions (regex) are one of those skills that seem intimidating at first, but once they click, they’ll …
8 min Read
R Tables & Contingency Analysis - Complete Guide
Tables are fundamental tools for data exploration and analysis, providing concise summaries of categorical variables and …
5 min Read
R Time Series Analysis - Complete Guide
Time series analysis is essential for analyzing data ordered chronologically,whether tracking stock prices, weather …
6 min Read
Check Data Type of R Data Frame Columns - 5 Methods
When you load data into R, understanding the data types of each column is crucial. If a column should be numeric but R …
8 min Read
How to Calculate Expected Value in R
Expected value is the average outcome you’d expect from a random process. It’s crucial in statistics, …
3 min Read
How to Check if a Package is Installed in R
One of the first things you’ll do in R is load packages to extend functionality. But before you can load a package …
7 min Read
How to Find the Antilog of Values in R
The antilog (or inverse logarithm) is the process of finding the original value from its logarithmic representation. If …
2 min Read
How to Use diff Function in R
The diff() function calculates differences between consecutive elements in a vector or time series. It’s essential …
2 min Read
How to Use rcorr() in R to Create a Correlation Matrix with P-Values
If you’ve ever calculated correlation in R using cor(), you got just the correlation coefficients. But in real …
9 min Read
How to Use the assign() Function in R
The assign() function creates variables programmatically;useful when you don’t know the variable name until …
3 min Read
How to Use the cat() Function in R to Concatenate Objects
The cat() function concatenates and prints objects to the console or file. It’s commonly used for creating …
3 min Read
How to Use the dist Function in R
The dist() function calculates distances between observations (rows) in a dataset. It’s fundamental for …
2 min Read
How to Use the identical() Function in R
The identical() function performs a strict equality test;it checks if two objects are exactly the same in every way. …
3 min Read
R Correlation Analysis - Complete Guide
Introduction You’re analyzing customer data and notice something interesting: customers with higher income seem to …
13 min Read
Data Cleaning in R - Complete Guide: Handle Missing Values, Duplicates & Outliers
Data cleaning is the most time-consuming part of any data analysis project. I’d estimate that 70-80% of my time as …
8 min Read
Calculate Z Score in Excel with Examples
The function to calculate z-score in Excel is STANDARDIZE(). This function accepts input parameters like data set, mean, …
5 min Read
Can Z Score be Negative
Yes, Z-Score can be negative. The negative z score value represents the raw score value that is either left or below the …
1 min Read
Find Critical Value of Z
In this article, we will discuss what is the critical value of z and when to use the critical value of z. We will …
7 min Read
Find the Area between Two Negative Z Scores
The area between two negative scores can be found by finding the area between two z-score and subtracting the small area …
2 min Read
Find the Area between two z scores?
In this article, we will discuss step by step guide on how to find the area between two z scores on both sides of the …
2 min Read
Find the area under Standard Normal Curve to the left of Z
The normal distribution is a continuous probability distribution. The total area under the standard normal curve is …
2 min Read
Find the Area under Standard Normal Curve to the right of Z
In this article, we will discuss step by step guide on how to find the area under the standard normal curve to the right …
2 min Read
Find the z-score for having an area 0.09
In this blog post, we will discuss how to find the z-score for having an area 0.09 to the left of the standard normal …
1 min Read
Find Z score of top 5 percentile of a Normal Distribution?
Z Score for the top 5 percentile of a normal distribution is 1.645. To find the top 5th percentile of a normal …
2 min Read
How to Find Percentiles from Z-Score on TI-84
The Normal Cumulative Distribution Function normalcdf() is used to find percentiles from the z score on the TI-84 …
3 min Read
How to Find Z Score on TI-84 plus Calculator
The Inverse Normal Probability Distribution Function invNorm() is used to find z score from the percentile on TI-84 plus …
3 min Read
How to Find Z Score on TI-NSpire?
The Inverse Normal Probability Distribution Function invNorm() is used to find the z score on TI-NSpire. invNorm(area, …
3 min Read
How to Transform a set of raw scores into a set of z-scores
To transform the set of raw scores into a set of z-scores in order, you will need to convert them into a standard normal …
2 min Read
Negative Z Score Table
A negative Z score value indicates the raw score value is either left or below the mean of the standard normal …
4 min Read
One Sample Proportion z-test
The one-sample proportion Z-test is a statistical tool used to conduct a hypothesis test about population …
4 min Read
One Sample Z-Test in R
The one-sample Z-test is a statistical hypothesis test used to determine whether the mean of a single sample is …
3 min Read
Z Score Calculator – How to use Z-Score calculator
Z score allows a comparison between two scores that are from different normal distributions of raw scores to …
3 min Read
Z Score Table and Chart
Z table or the Z-score table also called the standard normal table is a mathematical table used to find the probability …
9 min Read
Z-Score - Definition, Formula, and Calculation
What is a Z-Score? Z-score is the distance of the raw score value from the mean in terms of standard deviation. Raw …
6 min Read
How to Calculate Quantiles by Group in R
Calculating quantiles by group is crucial for understanding data distribution within subgroups. Instead of a single …
3 min Read
How to Calculate Rolling Correlation in R
Rolling correlation calculates correlation coefficients across a moving window of data. It’s invaluable when …
3 min Read
How to Check which Package Version is Loaded in R
Checking package versions is critical for reproducibility and debugging. When code breaks after updating packages, the …
2 min Read
How to Create a Multi-Line Comment in R
Comments are essential for readable, maintainable code. While R doesn’t have a native block comment syntax (like …
3 min Read
How to Use sign() Function in R
The sign() function returns the sign of a number: -1 for negative, 0 for zero, and 1 for positive. It’s simpler …
2 min Read
How to Use the get() Function in R to Retrieve Named Objects
The get() function retrieves an object by name when you don’t know the object’s name until runtime. …
3 min Read
How to Use the sink() Function in R
The sink() function redirects all console output (print statements, results) to a file instead of displaying it on …
3 min Read
How to Use with() and within() Functions in R
The with() and within() functions allow you to work with data frame columns as if they were variables in your workspace. …
4 min Read