Create Functional Index

MySQL

For analytical purposes, we frequently query the rental table with conditions similar to DATE_FORMAT(return_date, '%Y-%m') = 'YYYY-MM' (where 'YYYY-MM' represents a specific year and month). To significantly improve the performance of these queries, create a functional index named idx_return_date_func on the return_date column, utilizing the DATE_FORMAT function.

Expected result Columns: 15 · Rows: 1

Table	Non_unique	Key_name	Seq_in_index	Column_name	Collation	Cardinality	Sub_part	Packed	Null	Index_type	Comment	Index_comment	Visible	Expression

Write your query below and click "Check it!". Tables are described in the right pane.

The query result will appear here. Ctrl+Enter - Run query

Querynomicon Database: table structure and overview

Querynomicon (SQLite) is a compact training database for learning SQL fundamentals with clear and simple examples.

This page presents the tables, key columns, and sample rows for hands-on SQL practice.

The Querynomicon database contains 5 main tables.

More about the Querynomicon database: schema, sample queries and all exercises →

List of tables

department - table of departments.

identDepartment ID
nameDepartment name
buildingBuilding name

ident	name	building
gen	Genetics	Chesson

little_penguins - table of little penguins.

speciesPenguin species
islandIsland of residence
bill_length_mmBill length, mm
bill_depth_mmBill depth, mm
flipper_length_mmFlipper length, mm
body_mass_gBody mass, g
sexSex

species	island	bill_length_mm	bill_depth_mm	flipper_length_mm	body_mass_g	sex
Gentoo	Biscoe	52.1	17	230	5550	MALE

penguins - table of penguins.

speciesPenguin species
islandIsland of residence
bill_length_mmBill length, mm
bill_depth_mmBill depth, mm
flipper_length_mmFlipper length, mm
body_mass_gBody mass, g
sexSex

species	island	bill_length_mm	bill_depth_mm	flipper_length_mm	body_mass_g	sex
Gentoo	Biscoe	52.1	17	230	5550	MALE

staff - table of employees.

identEmployee number
personalEmployee first name
familyEmployee last name
deptDepartment
ageAge

ident	personal	family	dept	age
7	Abram	Chokshi	gen	23

machine - table of machines.

identMachine ID
nameMachine name
detailsJSON with details

ident	name	details
1	WY401	{"acquired": "2023-05-01"}
2	Inphormex	{"acquired": "2021-07-15", "refurbished": "2023-10-22"}
3	AutoPlate 9000	{"note": "needs software update"}

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Create Functional Index