Beginner Level
Basic Syntax: Learn SQL keywords (SELECT, FROM, WHERE, etc.).
Data Retrieval: Start with simple SELECT statements.
Filtering: Use WHERE clause for data filtering.
Sorting and Aggregation: ORDER BY for sorting, GROUP BY for aggregation.
Joins: Understand INNER JOIN, LEFT JOIN, RIGHT JOIN.
Subqueries: Use nested SELECT statements for more complex queries.
NULL Handling: Learn to handle NULL values with IS NULL, COALESCE, etc.
Transactions: Manage data consistency with transactions (BEGIN, COMMIT, ROLLBACK).
Advanced Filtering: CASE statements, UNION, EXISTS, INTERSECT, EXCEPT.
Dates and Times: Functions like DATE, TIME, DATEADD, DATEDIFF.