Correlated Subquery in SELECT?!

Subqueries in SELECT execute for EVERY row! This correlated subquery runs once per row, creating a performance nightmare. This is why queries are slow!

#sql #sqltricks #correlatedsubquery #selectclause #performance #sqlweird #sqlquiz #codingchallenge #sqlshorts #sqlwtf #subqueries #advancedsql

https://www.youtube.com/watch?v=GdfjEk34nRQ

Correlated Subquery in WHERE?!

Correlated subqueries in WHERE execute for EVERY row! They reference outer query columns, creating a performance nightmare. This is why queries are slow!

#sql #sqltricks #correlatedsubquery #whereclause #performance #sqlweird #sqlquiz #codingchallenge #sqlshorts #sqlwtf #subqueries #advancedsql

https://www.youtube.com/watch?v=wQqeMeQuW7c

Correlated Subquery With NULL Returns WHAT?!

Correlated subquery with NULL comparison returns something impossible! NULL = NULL in subquery breaks correlation logic! Watch!

#sql #sqltricks #database #sqltutorial #correlatedsubquery #null #sqlquiz #codingchallenge #sqlshorts #sqlbugs #subqueries #sqlwtf

https://www.youtube.com/watch?v=0gi1cUqrgA4