I have one table named GUYS(ID,NAME,PHONE) and i need to add a count of how many guys have the same name and at the same time show all of them so i can't group them.
example:
ID NAME PHONE
1 John 335
2 Harry 444
3 James 367
4 John 742
5 John 654
the wanted output should be
ID NAME PHONE COUNT
1 John 335 3
2 Harry 444 1
3 James 367 1
4 John 742 3
5 John 654 3
how could i do that? i only manage to get lot of guys with different counts.
thanks
Update for 8.0+: This answer was written well before MySQL version 8, which introduced window functions with mostly the same syntax as the existing ones in Oracle.
In this new syntax, the solution would be
SELECT
t.name,
t.phone,
COUNT('x') OVER (PARTITION BY t.name) AS namecounter
FROM
Guys t
The answer below still works on newer versions as well, and in this particular case is just as simple, but depending on the circumstances, these window functions are way easier to use.
Older versions: Since MySQL, until version 8, didn't have analytical functions like Oracle, you'd have to resort to a sub-query.
Don't use GROUP BY, use a sub-select to count the number of guys with the same name:
SELECT
t.name,
t.phone,
(SELECT COUNT('x') FROM Guys ct
WHERE ct.name = t.name) as namecounter
FROM
Guys t
You'd think that running a sub-select for every row would be slow, but if you've got proper indexes, MySQL will optimize this query and you'll see that it runs just fine.
In this example, you should have an index on Guys.name. If you have multiple columns in the where clause of the subquery, the query would probably benefit from a single combined index on all of those columns.
Use an aggregate Query:
select g.ID, g.Name, g.Phone, count(*) over ( partition by g.name ) as Count
from
Guys g;
You can still use a GROUP BY for the count, you just need to JOIN it back to your original table to get all the records, like this:
select g.ID, g.Name, g.Phone, gc.Count
from Guys g
inner join (
select Name, count(*) as Count
from Guys
group by Name
) gc on g.Name = gc.Name
In Oracle DB you can use
SELECT ID,NAME,PHONE,(Select COUNT(ID)From GUYS GROUP BY Name)
FROM GUYS ;
DECLARE #tbl table
(ID int,NAME varchar(20), PHONE int)
insert into #tbl
select
1 ,'John', 335
union all
select
2 ,'Harry', 444
union all
select
3 ,'James', 367
union all
select
4 ,'John', 742
union all
select
5 ,'John', 654
SELECT
ID
, Name
, Phone
, count(*) over(partition by Name)
FROM #tbl
ORDER BY ID
select id, name, phone,(select count(name) from users u1 where u1.name=u2.name) count from users u2
try
select column1, count(1) over ()
it should help
Related
I'm trying to get months of Employees' birthdays that are found in at least 2 rows
I've tried to unite birthday information table with itself supposing that I could iterate through them abd get months that appear multiple times
There's the question: how to get birthdays with months that repeat more than once?
SELECT DISTINCT e.EmployeeID, e.City, e.BirthDate
FROM Employees e
GROUP BY e.BirthDate, e.City, e.EmployeeID
HAVING COUNT(MONTH(b.BirthDate))=COUNT(MONTH(e.BirthDate))
UNION
SELECT DISTINCT b.EmployeeID, b.City, b.BirthDate
FROM Employees b
GROUP BY b.EmployeeID, b.BirthDate, b.City
HAVING ...
Given table:
| 1 | City1 | 1972-03-26|
| 2 | City2 | 1979-12-13|
| 3 | City3 | 1974-12-16|
| 4 | City3 | 1979-09-11|
Expected result :
| 2 | City2 |1979-12-13|
| 3 | City3 |1974-12-16|
Think of it in steps.
First, we'll find the months that have more than one birthday in them. That's the sub-query, below, which I'm aliasing as i for "inner query". (Substitute MONTH(i.Birthdate) into the SELECT list for the 1 if you want to see which months qualify.)
Then, in the outer query (o), you want all the fields, so I'm cheating and using SELECT *. Theoretically, a WHERE IN would work here, but IN can have unfortunate side effects if a NULL comes back, so I never use it. Instead, there's a correlated sub=query; which is to say we look for any results where the month from the outer query is equal to the months that make the cut in the inner (correlated sub-) query.
When using a correlated sub-query in the WHERE clause, the SELECT list doesn't matter. You could put 1/0 and it won't throw an error. But I always use SELECT 1 to show that the inner query isn't actually returning any results to the outer query. It's just there to look for, well, the correlation between the two data sets.
SELECT
*
FROM
#table AS o
WHERE
EXISTS
(
SELECT
1
FROM
#table AS i
WHERE
MONTH(i.Birthdate) = MONTH(o.Birthdate)
GROUP BY
MONTH(i.Birthdate)
HAVING
COUNT(*) > 1
);
Seems to be an odd requirement.
This might help with some tweaks. Works in Oracle.
SELECT DATE FROM TABLE WHERE EXTRACT(MONTH FROM DATE)=EXTRACT(MONTH FROM SOMEDATE);
Give this a try and you may be able to dispense with your UNION:
SELECT
EmployeeId
, City
, BirthDate
FROM Employees
GROUP BY
EmployeeId
, City
, BirthDate
HAVING COUNT(Month(BirthDate)) > 2
Here is another approach using GROUP_CONCAT. It's not exactly what you're looking for but it might do the job. Eric's approach is better though. (Note: This is for MySQL)
SELECT GROUP_CONCAT(EmployeeID) EmployeeID, BirthDate, COUNT(*) DupeCount
FROM Employees
GROUP BY MONTH(BirthDate)
HAVING DupeCount> 1;
This is a question on a test. I have a table with two columns. I want to pivot on one of them and output the other.
Table structure:
(Name varchar(10), Age int)
I need output with age values as columns and Names listed below each age value.
From searching, I only see examples where there is at least one other column that is used to "group by" for want of a better term. In other words, there is a common factor in each row of the output. My problem does not have this property.
I tried:
SELECT
[agevalue1], [agevalue2], [agevalue3], [agevalue4]
FROM
(SELECT Name, Age FROM MyClass) AS SourceTable
PIVOT
(MAX(Name)
FOR Age IN ([agevalue1], [agevalue2], [agevalue3], [agevalue4])
) AS PivotTable;
I specified agevalue* as a string, i.e. in quotes. I got the column headings alright but a row of NULLS below them.
P.S.: The solution does not need to use pivot but I couldn't think of an alternative approach.
Sample Data:
Name Age
Bob 11
Rick 25
Nina 30
Sam 11
Cora 16
Rachel 25
Desired output:
11 16 25 30
Bob Cora Rick Nina
Sam NULL Rachel NULL
Try this :
with tab as
(
Select 'A' Name, 10 Age union all
Select 'B',11 union all
Select 'c',10 union all
Select 'D',11 union all
Select 'E',11 union all
Select 'F',11
)
select distinct
Age
, stuff((
select ',' + g.Name
from tab g
where g.age = g1.age
order by g.age
for xml path('')
),1,1,'') as Names_With_Same_Age
from tab g1
group by g1.age,Name
To group these together in one row:
11 16 25 30
Bob Cora Rick Nina
and separate them from another set, like:
11 16 25 30
Sam NULL Rachel NULL
they must have something different between each row, since doing a MAX(Name) would get you only one Name for each Age.
This query creates a number that links a particular Age to a row number and then pivots the result. As you said, the PIVOT will group by all columns not referenced in the PIVOT function, so it will group by this row indexer, separating the values like you wanted.
;WITH IndexedClass AS
(
SELECT
M.Name,
M.Age,
-- The ordering will determine which person goes first for each Age
RowIndexer = ROW_NUMBER() OVER (PARTITION BY M.Age ORDER BY M.Name)
FROM
MyClass AS M
)
SELECT
P.[11],
P.[16],
P.[25],
P.[30]
FROM
IndexedClass AS I
PIVOT (
MAX(I.Name) FOR I.Age IN ([11], [16], [25], [30])
) AS P
Let's suppose we have a table T1 and a table T2. There is a relation of 1:n between T1 and T2. I would like to select all T1 along with all their T2, every row corresponding to T1 records with T2 values concatenated, using only SQL-standard operations.
Example:
T1 = Person
T2 = Popularity (by year)
for each year a person has a certain popularity
I would like to write a selection using SQL-standard operations, resulting something like this:
Person.Name Popularity.Value
John Smith 1.2,5,4.2
John Doe NULL
Jane Smith 8
where there are 3 records in the popularity table for John Smith, none for John Doe and one for Jane Smith, their values being the values represented above. Is this possible? How?
I'm using Oracle but would like to do this using only standard SQL.
Here's one technique, using recursive Common Table Expressions. Unfortunately, I'm not confident on its performance.
I'm sure that there are ways to improve this code, but it shows that there doesn't seem to be an easy way to do something like this using just the SQL standard.
As far as I can see, there really should be some kind of STRINGJOIN aggregate function that would be used with GROUP BY. That would make things like this much easier...
This query assumes that there is some kind of PersonID that joins the two relations, but the Name would work too.
WITH cte (id, Name, Value, ValueCount) AS (
SELECT id,
Name,
CAST(Value AS VARCHAR(MAX)) AS Value,
1 AS ValueCount
FROM (
SELECT ROW_NUMBER() OVER (PARTITION BY Name ORDER BY Name) AS id,
Name,
Value
FROM Person AS per
INNER JOIN Popularity AS pop
ON per.PersonID = pop.PersonID
) AS e
WHERE id = 1
UNION ALL
SELECT e.id,
e.Name,
cte.Value + ',' + CAST(e.Value AS VARCHAR(MAX)) AS Value,
cte.ValueCount + 1 AS ValueCount
FROM (
SELECT ROW_NUMBER() OVER (PARTITION BY Name ORDER BY Name) AS id,
Name,
Value
FROM Person AS per
INNER JOIN Popularity AS pop
ON per.PersonID = pop.PersonID
) AS e
INNER JOIN cte
ON e.id = cte.id + 1
AND e.Name = cte.Name
)
SELECT p.Name, agg.Value
FROM Person p
LEFT JOIN (
SELECT Name, Value
FROM (
SELECT Name,
Value,
ROW_NUMBER() OVER (PARTITION BY Name ORDER BY ValueCount DESC)AS id
FROM cte
) AS p
WHERE id = 1
) AS agg
ON p.Name = agg.Name
This is an example result:
--------------------------------
| Name | Value |
--------------------------------
| John Smith | 1.2,5,4.2 |
--------------------------------
| John Doe | NULL |
--------------------------------
| Jane Smith | 8 |
--------------------------------
As per in Oracle you can use listagg to achive this -
select t1.Person_Name, listagg(t2.Popularity_Value)
within group(order by t2.Popularity_Value)
from t1, t2
where t1.Person_Name = t2.Person_Name (+)
group by t1.Person_Name
I hope this will solve your problem.
But the comment you have given after #DavidJashi question .. well this is not sql standard and I think he is correct. I am also with David that you can not achieve this in pure sql statement.
I know that I'm SUPER late to the party, but for anyone else that might find this, I don't believe that this is possible using pure SQL92. As I discovered in the last few months fighting with NetSuite to try to figure out what Oracle methods I can and cannot use with their ODBC driver, I discovered that they only "support and guarantee" SQL92 standard.
I discovered this, because I had a need to perform a LISTAGG(). Once I found out I was restricted to SQL92, I did some digging through the historical records, and LISTAGG() and recursive queries (common table expressions) are NOT supported in SQL92, at all.
LISTAGG() was added in Oracle SQL version 11g Release 2 (2009 – 11 years ago: reference https://oracle-base.com/articles/misc/string-aggregation-techniques#listagg) , CTEs were added to Oracle SQL in version 9.2 (2007 – 13 years ago: reference https://www.databasestar.com/sql-cte-with/).
VERY frustrating that it's completely impossible to accomplish this kind of effect in pure SQL92, so I had to solve the problem in my C# code after I pulled a ton of extra unnecessary data. Very frustrating.
I am looking for the AVERAGE (overall) of the MINIMUM number (grouped by person).
My table looks like this:
Rank Name
1 Amy
2 Amy
3 Amy
2 Bart
1 Charlie
2 David
5 David
1 Ed
2 Frank
4 Frank
5 Frank
I want to know the AVERAGE of the lowest scores. For these people, the lowest scores are:
Rank Name
1 Amy
2 Bart
1 Charlie
2 David
1 Ed
2 Frank
Giving me a final answer of 1.5 - because three people have a MIN(Rank) of 1 and the other three have a MIN(Rank) of 2. That's what I'm looking for - a single number.
My real data has a couple hundred rows, so it's not terribly big. But I can't figure out how to do this in a single, simple statement. Thank you for any help.
Try this:
;WITH MinScores
AS
(
SELECT
"Rank",
Name,
ROW_NUMBER() OVER(PARTITION BY Name ORDER BY "Rank") row_num
FROM Table1
)
SELECT
CAST(SUM("Rank") AS DECIMAL(10, 2)) /
COUNT("Rank")
FROM MinScores
WHERE row_num = 1;
SQL Fiddle Demo
Selecting the set of minimum values is straightforward. The cast() is necessary to avoid integer division later. You could also avoid integer division by casting to float instead of decimal. (But you should be aware that floats are "useful approximations".)
select name, cast(min(rank) as decimal) as min_rank
from Table1
group by name
Now you can use the minimums as a common table expression, and select from it.
with minimums as (
select name, cast(min(rank) as decimal) as min_rank
from Table1
group by name
)
select avg(min_rank) avg_min_rank
from minimums
If you happen to need to do the same thing on a platform that doesn't support common table expressions, you can a) create a view of minimums, and select from that view, or b) use the minimums as a derived table.
You might try using a derived table to get the minimums, then get the average minimum in the outer query, as in:
-- Get the avg min rank as a decimal
select avg(MinRank * 1.0) as AvgRank
from (
-- Get everyone's min rank
select min([Rank]) as MinRank
from MyTable
group by Name
) as a
I think the easiest one will be
for max
select name , max_rank = max(rank)
from table
group by name;
for average
select name , avg_rank = avg(rank)
from table
cgroup by name;
I have a simple enough issue that has been surprisingly difficult to locate online. Perhaps I am searching on improper keywords so I wanted to stop in and ask you guys because your site has been a blessing with my studies. See below scenario:
Select student, count(*) as Total, (the unknown variable: book1, book2, book3, book4, ect...) from mystudies.
Essentially all I would like to do is list out all books for a unique student id that matches the Total count. Could someone point me in the right direction, a good read or anything, so I can get a step going in the correct direction? I am assuming it would be done via a left join (not sure how to do the x1, x2, x3 part) and then just link the two by the unique student id number (no duplicates) but everyone online points to pivot but pivot appears to put all the rows into columns instead of one single column. SQL server 2005 is the platform of choice.
Thanks!
Sorry
The following query produces my unique id (the student) and the student's count for all duplicate entries in the table:
select student, count(*) as Total
from mystudies
group by student order by total desc
the part I don't know is how to create the left join on the table unique id (boookid)
select mystudies1.student, mystudies1.total, mystudies2.bookid
from ( select student, count(*) as Total
from mystudies
group by student
) mystudies1
left join
( select student, bookid
from mystudies
) mystudies2
on mystudies1.student=mystudies2.student
order by mystudies1.total desc, mystudies1.student asc
Obviously the above row will produce results similar to the following:
Student Total BookID
000001 3 100001
000001 3 100002
000001 3 100003
000002 2 200001
000002 2 200002
000003 1 300001
But what I actually want is something similar to the following:
Student Total BookID
000001 3 100001, 100002, 100003
000002 2 200001, 200002
000003 1 300001
I assumed it had to be done in a left join so that it didn't alter the actual count being performed on the student. thanks!
In SQL-Server use the FOR XML Path Method:
SELECT Student,
Total,
STUFF(( SELECT ', ' + BookID
FROM MyStudies books
WHERE Books.Student = MyStudies.Student
FOR XML PATH(''), TYPE
).value('.', 'VARCHAR(MAX)'), 1, 2, '') AS Books
FROM ( SELECT Student, COUNT(*) AS Total
FROM myStudies
GROUP BY Student
) MyStudies
I have previously given a full explanation of how the XML PATH Method works here. With a further improvement to my answer pointed out here
SQL Server Fiddle
In MySQL AND SQLite you can use the GROUP_CONCAT function:
SELECT Student,
COUNT(*) AS Total,
GROUP_CONCAT(BookID) AS Books
FROM myStudies
GROUP BY Student
MySQL Fiddle
SQLite Fiddle
In Postgresql you can use the ARRAY_AGG Function:
SELECT Student,
COUNT(*) AS Total,
ARRAY_AGG(BookID) AS Books
FROM myStudies
GROUP BY Student
Postgresql Fiddle
In oracle you can use the LISTAGG Function
SELECT Student,
COUNT(*) AS Total,
LISTAGG(BookID, ', ') WITHIN GROUP (ORDER BY BookID) AS Books
FROM myStudies
GROUP BY Student
Oracle SQL Fiddle