search
Search
Publish
menu
menu search toc more_vert
Robocat
Guest 0reps
Thanks for the thanks!
close
Comments
Log in or sign up
Cancel
Post
account_circle
Profile
exit_to_app
Sign out
help Ask a question
Share on Twitter
search
keyboard_voice
close
Searching Tips
Search for a recipe: "Creating a table in MySQL"
Search for an API documentation: "@append"
Search for code: "!dataframe"
Apply a tag filter: "#python"
Useful Shortcuts
/ to open search panel
Esc to close search panel
to navigate between search results
d to clear all current filters
Enter to expand content preview
icon_star
Doc Search
icon_star
Code Search Beta
SORRY NOTHING FOUND!
mic
Start speaking...
Voice search is only supported in Safari and Chrome.
Navigate to
A
A
share
thumb_up_alt
bookmark
arrow_backShare
Twitter
Facebook
thumb_up
0
thumb_down
0
chat_bubble_outline
0
auto_stories new
settings

Finding duplicate values in MySQL

Database
chevron_right
MySQL
chevron_right
Cookbooks
chevron_right
Functions Cookbooks
schedule Jul 1, 2022
Last updated
local_offer MySQL
Tags
tocTable of Contents
expand_more

This can be done using the COUNT method.

SELECT column, COUNT(column)
FROM table
GROUP BY column
HAVING COUNT(column) > 1;

Example

Consider the following table about whether students hold a drivers license:

student_id

full_name

age

has_license

1

Sky Towner

17

0

2

Ben Davis

19

1

3

Travis Apple

18

0

4

Arthur David

16

0

5

Benjamin Town

17

1

The above sample table can be created using the code here.

Basic usage

To check for duplicate values in the age column:

SELECT age, COUNT(age)
FROM drivers_license
GROUP BY age
HAVING COUNT(age) > 1;
+------+------------+
| age | COUNT(age) |
+------+------------+
| 17 | 2 |
+------+------------+

The result shows that we have two records with age 17.

robocat
Published by Arthur Yanagisawa
Edited by 0 others
Did you find this page useful?
thumb_up
thumb_down
Ask a question or leave a feedback...
thumb_up
0
thumb_down
0
chat_bubble_outline
0
settings
Enjoy our search
Hit / to insta-search docs and recipes!