SQL Project: E-commerce Sales Analysis
A complete SQL portfolio project: analyse a year of online shop orders in MySQL. Revenue, monthly trend, top products, margins, repeat buyers, RFM, cohorts.
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61 articles · page 2 of 6 · Clear filtersSQL Project: HR and Payroll Analytics
An HR analytics SQL project: headcount and attrition, current salaries from history, raises with LAG, top earners, org chart with a recursive CTE, tenure.
SQL Stored Procedures
Learn MySQL stored procedures step by step: CREATE PROCEDURE, DELIMITER, IN and OUT parameters, variables, IF and loops, error handling and transactions.
Database Normalization (1NF, 2NF, 3NF)
Database normalization step by step: anomalies, 1NF, 2NF, 3NF and BCNF, normalizing a messy orders table into related tables, and when to denormalize.
SQL INTERSECT and EXCEPT
Find rows common to two queries with INTERSECT and rows in one but not the other with EXCEPT, supported in MySQL 8.0.31+, plus the JOIN and EXISTS alternatives.
SQL Joins Explained
SQL joins explained visually and step by step: INNER, LEFT, RIGHT, FULL OUTER, CROSS and SELF JOIN on the same two tables, with real MySQL results.
SQL LAG and LEAD Functions
Compare a row with the previous or next row using SQL LAG and LEAD: month-over-month change, gaps between orders, defaults, offsets, FIRST_VALUE and LAST_VALUE.
SQL Injection and Prepared Statements
How SQL injection works, shown on a demo login table, and how to prevent it with prepared statements in MySQL and Python, plus a QA testing checklist.
SQL Indexes
Learn SQL indexes in MySQL: how a B-tree index speeds up queries, CREATE INDEX, composite indexes, the leftmost-prefix rule, and when an index is not used.
SQL EXISTS, ANY and ALL
Learn SQL EXISTS and NOT EXISTS for checking related rows, why NOT EXISTS beats NOT IN with NULLs, and how ANY and ALL compare a value with a…
SQL EXPLAIN and Query Optimization
Read MySQL EXPLAIN output column by column, use EXPLAIN ANALYZE and EXPLAIN FORMAT=TREE, and apply 10 practical SQL query optimization tips with real examples.
SQL User-Defined Functions
Create your own MySQL functions with CREATE FUNCTION: parameters, RETURNS, DETERMINISTIC, using functions in queries, and function vs stored procedure.
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