SQL
Advanced Date Based Analysis
Period over period comparison, cohort retention, complete date ranges with no missing buckets, and rolling windows over time.
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SQL
Stored Procedures and Parameters
Named procedural code stored in the database. Learn CREATE PROCEDURE, IN, OUT and INOUT parameters, control flow, and when a procedure is the right to...
SQL
User Defined Functions
Functions return a value and can be used inside a query. Learn CREATE FUNCTION, determinism, the difference from procedures, and the performance trap.
SQL
Trigger Basics: BEFORE, AFTER, INSERT, UPDATE and DELETE
Code the database runs automatically when data changes. Learn the six trigger points, the NEW and OLD row references, and how to write an audit trigge...
SQL
Trigger Use Cases and Limitations
What triggers are genuinely good at, the costs they impose, and the honest list of reasons teams end up removing them.
SQL
Temporary Tables and Session Scope
A real table that exists only for your session. Learn CREATE TEMPORARY TABLE, its scope and lifetime, indexing it, and the dialect differences.
SQL
Temporary Tables vs CTEs vs Views vs Derived Tables
Four ways to name an intermediate result, and a decision rule for choosing between them based on scope, reuse and whether you need an index.
SQL
BEGIN, COMMIT, ROLLBACK and Savepoints
Grouping statements into one unit of work that either fully applies or fully undoes. Learn transaction boundaries, savepoints, autocommit and what sil...
SQL
ACID Properties Explained
Atomicity, consistency, isolation and durability - what each guarantee actually promises, how the database delivers it, and where each one can be weak...
SQL
Isolation Levels and Read Phenomena
The four isolation levels, the three anomalies they prevent, and what each database actually defaults to - with the session by session demonstrations.
SQL
Locks: Shared, Exclusive, Row and Table Level
How the database stops two transactions corrupting each other: lock modes, granularity, locking reads, and why an unindexed WHERE clause can lock a wh...
SQL
Deadlocks and Lock Contention
Why two transactions can wait for each other forever, how the database resolves it, and the design habits that prevent deadlocks and reduce contention...