Want to upgrade your SQL skills for an interview or for your job? Here's how I'd
break down your time:

Common topics (should master these):
1. SELECT and WHERE for filtering and selection
2. COUNT, SUM, MAX, GROUP BY, HAVING for aggregating data"
3. DISTINCT, COUNT DISTINCT for producing useful distinct lists and distinct
4. OUTER (e.g. LEFT) and INNER JOIN when/where to use them
5. Strings and time conversions

Topics that come up regularly (be familiar with them):
1. DML/DDL/DCL concepts
2. Handling NULLs creatively (e.g. with COALESCE)
3. Subqueries and the impact of subqueries on efficiency of the query
4. Temporary tables
5. Self joins
6. Window functions like PARTITION, LEAD, LAG, NTILE
7. UDFs (user defined functions)
8. Use of indexes in querying to make operations faster.

Important, but more rare topics (useful to know):
1. Recursive CTEs
2. Dynamic SQL generation
3. Query optimization
4. Materialized views

What would you add, or change?

#datascience #data #sql

Posted by Eric Weber on LinkedIn
link: linkedin.com/in/eric-weber-060397b7