Sankalan Tech Insights

Nov 11, 20262 min read

SQL Challenge: Can You Group Customers by Income Using CASE WHEN?

Here is a practical problem you might face while preparing a customer analysis report. You have a customers table containing customer IDs, names and annual income. The business team wants to underst

Extract an Email Domain Using INSTR() and SUBSTR() in Oracle SQL
Nov 10, 20263 min read
SQL Tutorial: Clean Messy Employee Names Using TRIM(), LOWER(), and INITCAP()
Nov 9, 20264 min read
Can You Find Employees Who Joined This Month Using SQL? (Oracle TRUNC & ADD_MONTHS)
Nov 8, 20262 min read
SQL Challenge: Why Is Your SQL Query Still Returning NULL?
Nov 4, 20262 min read

SQL Challenge: How to Get Employee Names and Department Names Using JOIN
Imagine your manager asks you to prepare a report showing each employee's name along with their department name. You have two tables: "employees" – stores employee details. "departments" – stores dep
Nov 4, 20262 min read
SQL EXISTS vs JOIN: Find Customers Who Have Placed an Order
#88 SQL Challenge: Can You Find Customers Who Have Placed an Order? Imagine your manager asks you to find all customers who have placed at least one order. You have two tables. Some customers have pla
Oct 31, 20263 min read
SQL: WHERE, ORDER BY, and LIMIT — Why Your Query May Return the Wrong Employees
A SQL query can run successfully and still return the wrong result. Imagine your manager asks you to find the three highest-paid employees in the IT department. You write a query, execute it, and get
Oct 30, 20263 min read
SQL Filtering and Sorting: 5 Mistakes That Can Change Your Query Results
A SQL query can execute without errors and still produce an unexpected result. It might return the wrong employees, sort salaries incorrectly, or select the wrong three records. The problem often lies
Oct 29, 20263 min read
SQL SELECT Statement: Practical Examples for Beginners and Interview Preparation
The "SELECT" statement is one of the first things you learn when working with SQL. But knowing the syntax is only the beginning. In real projects, you need to retrieve the right columns, filter record
Oct 28, 20265 min read
A Single SQL Constraint Can Save Your Database From Bad Data — Do You Know Which One?
A Single SQL Constraint Can Save Your Database From Bad Data Imagine an order references a customer who doesn't exist. Your reports become unreliable, your joins return unexpected results, and debuggi
Oct 22, 20262 min read

Sankalan Tech Insights

Latest articles

SQL Challenge: Can You Group Customers by Income Using CASE WHEN?

Extract an Email Domain Using INSTR() and SUBSTR() in Oracle SQL

SQL Tutorial: Clean Messy Employee Names Using TRIM(), LOWER(), and INITCAP()

Can You Find Employees Who Joined This Month Using SQL? (Oracle TRUNC & ADD_MONTHS)

SQL Challenge: Why Is Your SQL Query Still Returning NULL?

SQL Challenge: How to Get Employee Names and Department Names Using JOIN

SQL EXISTS vs JOIN: Find Customers Who Have Placed an Order

SQL: WHERE, ORDER BY, and LIMIT — Why Your Query May Return the Wrong Employees

SQL Filtering and Sorting: 5 Mistakes That Can Change Your Query Results

SQL SELECT Statement: Practical Examples for Beginners and Interview Preparation

A Single SQL Constraint Can Save Your Database From Bad Data — Do You Know Which One?