Advanced SQL Techniques and Query Optimization
Relational Language
Edgar Codd's seminal work in the early 1970s laid the foundation for relational models through the introduction of relational algebra—a mathematical framework defining operations such as selection, projection, join, Cartesian product, intersection, union, and difference.
Users express their data needs using declarative langu ...
Posted on Sat, 08 Aug 2026 16:59:49 +0000 by soianyc
LeetCode SQL Problem Solutions (Part 4)
1907. Categorize Salary Counts
Table: Accounts
+-------------+------+
| Column | Type |
+-------------+------+
| account_id | int |
| income | int |
+-------------+------+
account_id is the primary key. Each row has monthly income of a bank account.
Query the number of accounts in each salary category:
Low Salary: income < 200 ...
Posted on Wed, 15 Jul 2026 16:44:03 +0000 by Bozebo
Understanding MySQL COUNT Window Function with Practical Examples
Window functions in MySQL enable advanced data analysis by performing calculations across rows without collapsing the result set. The COUNT() window function specifically allows counting elements within a defined window partition while preserving individual row details.
How Window Functions Work
Unlike traditional aggregate functions that group ...
Posted on Sun, 17 May 2026 23:26:58 +0000 by moonoo1974
Efficient Pagination and Window Functions in SQL Server
Paginatoin with Separate Count Query
When implementing pagination in SQL Server, one common approach is to execute two separate queries—one to retrieve the total record count and another to fetch the actual data page.
-- Retrieve total number of matching records
SELECT COUNT(*) AS TotalRecords
FROM Products
WHERE CategoryId = 5 AND IsActive = 1 ...
Posted on Sun, 17 May 2026 03:50:15 +0000 by Code_guy
Implementing SQL Window Functions for Advanced Analytics
Window functions enable complex analytical operations that were previously difficult or impossible with standard SQL. Unlike aggregate functions that collapse groups into single values, window functions perform calculations across related rows while preserving individual row details. Major databases like Oracle, SQL Server, and DB2 support wind ...
Posted on Fri, 08 May 2026 07:53:06 +0000 by markanite