SQLServer TSQLStudy Notes

Aggregations and Grouping

Master aggregate functions and GROUP BY/HAVING to summarize rows into meaningful totals, averages, and counts in SQL Server.

Backup and Restore

How SQL Server backup types, the recovery model, and restore sequences work together to protect data and meet recovery objectives.

Building a Reporting Query

A step-by-step walkthrough of designing a real-world T-SQL reporting query using joins, aggregation, window functions, and pivoting.

Constraints and Keys

Learn how PRIMARY KEY, FOREIGN KEY, UNIQUE, CHECK, DEFAULT, and NOT NULL constraints enforce data integrity directly at the database layer.

Data Types in SQL Server

A tour of SQL Server's core data types — numeric, character, date/time, and special types — and how to pick the right one.

Error Handling with TRY/CATCH

Learn how TRY...CATCH blocks intercept T-SQL runtime errors, how to inspect them with the ERROR_ functions, and how to combine them safely with transactions.

Execution Plans and Tuning

How to read SQL Server execution plans, identify costly operators, and apply indexing and query rewrites to improve performance.

High Availability Basics

Core SQL Server high-availability options — Always On Availability Groups, Failover Cluster Instances, and log shipping — and how they differ.

Indexes and Performance

Learn how clustered and nonclustered indexes speed up SQL Server queries, and how to read execution plans and statistics to diagnose slow queries.

Installing SQL Server and SSMS

A practical walkthrough of installing SQL Server and SQL Server Management Studio, and connecting to your first instance.

Joins in T-SQL

Understand how INNER, OUTER, CROSS, and self joins combine rows from multiple tables in SQL Server, and how to avoid common join pitfalls.

Security and Permissions

The principal-securable-permission model in SQL Server, from logins and users to roles and the principle of least privilege.

SELECT and Filtering

Learn how to retrieve exactly the rows and columns you need from SQL Server tables using SELECT, WHERE, and related filtering clauses.

SQL Server Agent Jobs

How SQL Server Agent automates scheduled tasks, jobs, steps, schedules, alerts, and operator notifications.

SQL Server Interview Questions

Commonly asked SQL Server and T-SQL interview questions with the reasoning behind strong answers, from indexing to isolation levels.

SQL Server vs Other Databases

How SQL Server compares to PostgreSQL, MySQL, and Oracle across architecture, tooling, licensing, and everyday development experience.

Stored Procedures

Understand how to create, parameterize, and execute stored procedures to encapsulate reusable, precompiled T-SQL logic on the server.

Subqueries and CTEs

Learn how to nest queries and use Common Table Expressions to break complex T-SQL logic into readable, reusable, and recursive building blocks.

T-SQL Best Practices

Practical, production-tested guidelines for writing T-SQL that is correct, performant, and maintainable in SQL Server.

T-SQL Quick Reference

A fast-lookup reference covering core T-SQL syntax: data types, joins, window functions, string/date functions, and common statements.

T-SQL Syntax Basics

Core T-SQL syntax rules — statements, batches, comments, identifiers, and control-of-flow — you need before writing real queries.

Temp Tables and Table Variables

Compare local temp tables, global temp tables, and table variables in SQL Server, and learn when each is the right tool for intermediate result sets.

Transactions and Locking

Understand how SQL Server groups statements into atomic transactions, uses locks to enforce isolation, and how deadlocks arise and get resolved.

Triggers in SQL Server

Learn how AFTER and INSTEAD OF triggers fire automatically in response to DML events, and how to use the inserted and deleted pseudo-tables correctly.