SQL reference and cheat sheet: syntax and descriptions for every major SQL command, clause, operator and function, each linked to its full tutorial chapter.
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Customer Relationship Management (CRM) Dashboard in HTML
A walkthrough of the CRM Dashboard in HTML: five interactive pages for deals, win rate, account managers, industries and lead sources, the KPIs it tracks, its six filters and how to load your own pipeline data.
SQL Window Functions: ROW_NUMBER, RANK, LAG and Running Totals
Learn SQL window functions with OVER and PARTITION BY: ROW_NUMBER, RANK and DENSE_RANK, running totals, LAG and LEAD, moving averages, NTILE and top-N per group, with exact output.
SQL Subqueries: Nested Queries in WHERE, FROM and SELECT
Learn SQL subqueries with worked examples: scalar and multi-row subqueries in WHERE, derived tables in FROM, correlated subqueries, NOT IN vs NOT EXISTS, and when to use a JOIN or CTE instead.
SQL EXISTS Operator: Test Whether a Subquery Returns Rows
SQL EXISTS tutorial: check whether a correlated subquery returns any rows, use NOT EXISTS to find missing matches, compare EXISTS vs IN vs JOIN, and avoid the NOT IN NULL trap, with worked examples and results.
SQL HAVING Clause: Filter Groups After GROUP BY (Examples)
Learn the SQL HAVING clause step by step: filter GROUP BY results with COUNT, SUM, AVG and MIN conditions, combine HAVING with WHERE, and avoid the errors beginners hit most often.
Hospital Operations KPI Scorecard in Google Sheets
Introduction The Hospital Operations KPI Scorecard in Google Sheets is a powerful, ready-to-use template designed to help healthcare administrators and hospital management teams track and analyze key performance indicators (KPIs) efficiently. By leveraging this scorecard, hospitals can monitor operational efficiency, quality of care, and overall performance through an intuitive and dynamic dashboard.Hospital Operations KPI Scorecard […]
SQL GROUP BY Clause: Group Rows and Aggregate Data (Examples)
SQL GROUP BY tutorial with a sample Orders table: syntax table, COUNT, SUM and AVG per group, grouping by several columns and by month, WHERE vs HAVING, common errors with fixes and practice exercises.
SQL FULL JOIN: Combine All Rows from Both Tables (Examples)
SQL FULL JOIN tutorial: return all rows from both tables, NULL where no match, find mismatches on either side, and emulate FULL JOIN in MySQL and SQLite.
SQL RIGHT JOIN: Keep All Rows from the Right Table (Examples)
SQL RIGHT JOIN explained with sample tables and six worked examples: keep every row from the right table, find orphan records, use COALESCE, and avoid the WHERE-vs-ON trap.