I need to find matches in a table with the same data. For example, I have a list of people with their birthdates. I need to get a list of all the people in the database with the same birthdate.
name birthdate
Patrick 1971-06-07
John 1971-06-07
Mary 1972-06-07
Ashley 1972-06-07
When I run this query
select a.name, b.name as name2
from #tmp_duplicates a
join #tmp_duplicates b on b.birthdate = a.birthdate
where a.name != b.name
I get:
name name2
John Patrick
Patrick John
Ashley Mary
Mary Ashley
I only need it to match once, so I am looking for:
name name2
John Patrick
Ashley Mary
How do I write the query to only match once?
Related
I have two tables:
Phone calls:
Caller
Receiver
012345
543210
123123
321321
People:
Person
Number
Jack
012345
Jane
123123
Bob
321321
Gill
543210
How can I join those tables to to get an output like this:
Caller
Receiver
Jack
Gill
Jane
Bob
I've tried
select * from phone_calls join person on phone_calls.caller = person.number and phone_calls.receiver = person.number
but this does not work.
Any help would be apprieciated.
Thank you,
T.
You can join the person table twice
SELECT p1.`Person`,p2.`Person` FROM phonecalls pc
INNER JOIN Person p1 ON p1.`Number` = pc.`Caller`
INNER JOIN Person p2 ON p2.`Number` = pc.`Receiver`
Person | Person
:----- | :-----
Jane | Bob
Jack | Gill
db<>fiddle here
I have students records. If I get John repeats more than 2 times on my database, how can I count how many records John has on the database?
________________
Name | Grade
________________
John | F
Mo | A
John | F
I want to know how many F's John gets? I'm connecting this database with C#
Are you looking for this?
SELECT count(Grade),Name
FROM YourTable
GROUP BY Name
You will have to group on both Name and Grade:
SELECT
[Name],
Grade,
Count(*) As Achieved
FROM
YourTable
GROUP BY
[Name],
Grade
I have a database table like the following (bad design I know, but there are a ton of rows like this):
person1 | person2 | counselor
Jane Doe | John Doe | Mary Smith
John Doe | Jane Doe | Mary Smith
Frank Jones| Ann Jones | Tom Jones
Ann Jones | Frank Jones | Tom Jones
I'm trying to figure out how to just select one of the 'unique' rows so that a result would look like:
person1 | person2 | counselor
Jane Doe | John Doe | Mary Smith
Frank Jones| Ann Jones | Tom Jones
I've tried various things like SELECT distinct and SELECT MIN(person1), etc., but am striking out.
You will have 6 permutations of (person1,person2,counselor) and you can use union with all of them. Finally use a where clause so only one row per combination will be returned.
Fiddle with sample data
select * from (
select person1,person2,counselor
from tablename
union
select person1,counselor,person2
from tablename
union
select person2,person1,counselor
from tablename
union
select person2,counselor,person1
from tablename
union
select counselor,person2,person1
from tablename
union
select counselor,person1,person2
from tablename) t
where person1 < person2 and person2 < counselor
SQL Fiddle Demo
I include a case where no reverse duplicated and also another case where person1 = person2, also include P2.* in select just for debug.
SELECT P1.person1, P1.person2, P1.counselor, P2.*
FROM patient P1
LEFT JOIN patient P2
ON P1.person1 = P2.person2
AND P1.person2 = P2.person1
AND P1.counselor = P2.counselor
WHERE
concat(P1.person1, P1.person2) <= concat(P2.person1, P2.person2)
OR P2.person1 is null
When P2 is NULL mean there isn't a reverse combination of person1, person2
But when the combination exists only choose the smaller one as string concatenation.
With ranked_records AS
(
select *,
ROW_NUMBER() OVER(Partition By person1, person2, counselor
Order By person) [ranked]
from address
)
select * from ranked_records
where ranked > 1
For more detail, like how to delete latest records and keep the older one.
For MySql and if you have Id, try this:
DELETE A1
From Address A1
Where Exists (Select * From Address A2
Where A2.person1= A1.person1
AND A2.person2 = A1.person2
AND A2.counselor = A1.counselor
AND A1.AddressID > A2.AddressID)
I have table like this:
title name
1 ADAM SMITH
1 JACK SMITH
1 ROBERT ABADI
2 JACK SMITH
2 JAMES ANDERSON
3 JACK SMITH
When I call data with query looks like
SELECT title, name, group_concat(name) as gname
FROM sample
GROUP BY title
The result is:
1 ADAM SMITH ADAM SMITH,JACK SMITH,ROBERT ABADI
2 JACK SMITH JACK SMITH,JAMES ANDERSON
3 JACK SMITH JACK SMITH
Now, I want to group by name again. so I call this query and results is following.
SELECT title, name, group_concat(distinct gname)
FROM
(
SELECT title, name, group_concat(name) as gname
FROM sample
GROUP BY title
) sub
GROUP BY sub.name
1 ADAM SMITH ADAM SMITH,JACK SMITH,ROBERT ABADI
2 JACK SMITH JACK SMITH,JAMES ANDERSON,JACK SMITH
But I don't want to have the 'JACK SMITH' twice on last column.
I know the reason because the first group_concat() results is string that can't not applied with 'DISTINCT' clause.
Any suggestions are appreciated.
Use a JOIN to get co-authors:
SELECT s1.name, GROUP_CONCAT(DISTINCT s2.name)
FROM sample AS s1
JOIN sample AS s2 ON s1.title = s2.title
GROUP BY s1.name
DEMO
If you don't want to show an author as a co-author of himself, add AND s1.name != s2.name to the ON condition.
I'm having some problems working out how to return the desired rows from the following mysql table:
first_name last_name collection
==========================================
Bob Jones 1
Ted Jones 1
Bob Jones 1
Bob Jones 2
Ted Baker 2
I want to return the count of names based on columns 'first_name' and 'last_name'. Ordinarily it would just be a simple case of using 'group by first_name, last_name', so we would have the following result: a count of 3 for Bob Jones, 1 for Ted Jones, and 1 for Ted Baker.
However, the difficulty is the third column 'collection'. I need to exclude duplicate names between collections, but not within collections. So we'd include all names in the count for the first collection, but only include names in the count from the second collection if they do NOT occur in the first collection.
So, the desired result would be as follows: a count of 2 for Bob Jones, 1 for Ted Jones, and 1 for Ted Baker.
first_name last_name collection included?
========================================== ===============
Bob Jones 1 Yes
Ted Jones 1 Yes
Bob Jones 1 Yes
Bob Jones 2 No
Ted Baker 2 Yes
I have really tried to get my head around this but I am starting to run out of ideas. Any help would be hugely appreciated... thanks!
Perhaps
SELECT first_name, last_name, COUNT( DISTINCT collection) AS cnt
FROM yourtable
GROUP BY first_name, last_name
The COUNT DISTINCT would eliminate the duplicate Bob/Jones/1 records.
Is this what you are expecting?
SELECT u1.first_name, u1.last_name, u1.collection FROM users u1
WHERE u1.collection = (SELECT min(u2.collection)
FROM users u2 WHERE u1.first_name = u2.first_name
AND u1.last_name = u2.last_name);
http://www.sqlfiddle.com/#!2/bd086/7