Transfer SQL Server Logins while Preserving SIDs
Move SQL logins with their SIDs so restored database users remain mapped on the destination server.
Category: SQL
Find and Fix Orphaned Users in SQL Server
Identify database users whose login SID no longer matches and remap them safely after a restore or migration.
Get the Size of Every MySQL Database and Table
Last updated: August 29, 2026. MySQL reports table data and index allocation through INFORMATION_SCHEMA.TABLES. The following queries convert the byte…
Fix SQL Server ‘Insufficient Access Rights’ During Backup
Last updated: August 26, 2026. A SQL Server backup can fail because the login lacks database backup permission or because…
Transfer SQL Server Logins and Passwords Between Instances
Last updated: August 29, 2026. Database users and server logins are separate SQL Server objects. When a database moves to…
SQL Data Types
Last updated: August 26, 2026. A column’s data type defines the values it can store and the operations a database…
SQL Aggregate Functions: COUNT, SUM, AVG, MIN, and MAX
Last updated: August 27, 2026. Aggregate functions calculate one result from multiple rows. The most common are COUNT, SUM, AVG,…
Practice SQL Queries
Last updated: August 27, 2026. Use the tutorial’s sample tables to practice read-only queries first. Start with a narrow SELECT,…
SQL ALTER TABLE
Last updated: August 27, 2026. Use ALTER TABLE to change an existing table definition. Exact options vary between database systems,…
SQL UNION and UNION ALL
Last updated: August 26, 2026. UNION combines compatible query results and removes duplicate rows. UNION ALL keeps duplicates and usually…