Notes/fundamentals
1
0
Fork 0
mirror of https://github.com/robindhole/fundamentals.git synced 2025-03-15 21:50:16 +00:00
Code Issues Packages Projects Releases Wiki Activity

Adds questions.

Browse Source
This commit is contained in:
Tanmay 2022-10-06 14:59:19 +01:00
parent a408ec280a
commit 7b32d3b6cb
1 changed files with 10 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
database/notes/09-subqueries-views.md
View File

@ -13,6 +13,7 @@
- [Index Range scan](#index-range-scan) - [Index Range scan](#index-range-scan)
- [Index seek](#index-seek) - [Index seek](#index-seek)
- [Some guidelines for optimizing MySQL queries](#some-guidelines-for-optimizing-mysql-queries) - [Some guidelines for optimizing MySQL queries](#some-guidelines-for-optimizing-mysql-queries)
- [Practice questions](#practice-questions)
## Sub-queries ## Sub-queries
@ -223,4 +224,12 @@ This happens when you specify a condition in WHERE clause like searching an empl
* Avoid unnecessary columns in SELECT clause * Avoid unnecessary columns in SELECT clause
Instead of using ‘SELECT *’, always specify columns in the SELECT clause to improve MySQL performance. Because unnecessary columns cause additional load on the database, slowing down its performance as well whole systematic process. Instead of using ‘SELECT *’, always specify columns in the SELECT clause to improve MySQL performance. Because unnecessary columns cause additional load on the database, slowing down its performance as well whole systematic process.
* Pagination * Pagination
* Avoid SELECT DISTINCT * Avoid SELECT DISTINCT
## Practice questions
* [Sub-queries - I](https://leetcode.com/problems/customers-who-never-order/)
* [Sub-queries - II](https://leetcode.com/problems/sales-person/)
* [Sub-queries - III](https://leetcode.com/problems/consecutive-available-seats/)
* [Sub-queries - IV](https://leetcode.com/problems/sales-analysis-ii/)
* [Sub-queries - V](https://leetcode.com/problems/students-with-invalid-departments/)
* [Sub-queries - VI](https://leetcode.com/problems/customer-who-visited-but-did-not-make-any-transactions/)