I have two tables tbPerson and tbComment with data such as below:
tbPerson
PersonID FirstName LastName
1 William Tell
2 Joe Smith
3 Sam Hampton
tbComment
CommentID PersonID CommentValue CommentPosition
45 2 This is my comment 100
46 2 This is my second comment 100
47 2 This is my third comment 100
48 1 A comment 101
49 3 This comment rules 102
50 3 A comment here 102
I need a query that only returns:
William Tell 101
Joe Smith 100
Sam Hampton 102
I figured it was something like below but this returns multiple rows. I only want the three rows.
SELECT FirstName, LastName, CommentPosition
FROM tbPerson
JOIN tbComment ON tbPerson.PersonID = tbComment.PersonID
GROUP BY FirstName, LastName, CommentPosition
For your data, your query should return only three rows. If you have multiple comments for a person, You need to choose which comment position you want.
The following would return the minimal value:
SELECT FirstName, LastName, MIN(CommentPosition) as CommentPosition
FROM tbPerson JOIN
tbComment
ON tbPerson.PersonID = tbComment.PersonID
GROUP BY FirstName, LastName;
Notice that CommentPosition was removed from the GROUP BY clause.
If comment position varies, try this:
SELECT FirstName, LastName, CommentPosition
FROM tbPerson
INNER JOIN (
SELECT PersonID, MIN(CommentPosition) AS CommentPosition
FROM tbComment
GROUP BY PersonID
) T1 ON tbPerson.PersonID = T1.PersonID
This will also handle the case of multiple people with the same name.
You can use SELECT DISTINCT FirstName, LastName, ...to get exactly what you want. Here's a tutorial on it.
http://www.mysqltutorial.org/mysql-distinct.aspx
Related
I know I can join Table #1 and Table #2 with a UNION and then filter out duplicate Id's using DISTINCT. However, for the duplicate contacts I'd like to change DrinkPreference to Coke/Pepsi.
Is this possible?
Starting Table #1
Id
FirstName
LastName
DrinkPreference
123
Tom
Bannon
Pepsi
124
Sarah
Smith
Pepsi
Starting Table #2
id
FirstName
LastName
DrinkPreference
125
Jim
Henry
Coke
123
Tom
Bannon
Coke
Table? #3 - combined with DrinkPreference set to Coke/Pepsi where contact exists in both tables?
Id
FirstName
LastName
DrinkPreference
125
Jim
Henry
Coke
123
Tom
Bannon
Coke/Pepsi
124
Sarah
Smith
Pepsi
You can try this one
SELECT coalesce(t1.firstname, t2.firstname) AS firstname,coalesce(t1.lastname,t2.lastname) AS lastname, CASE WHEN t1.drinkpreferences IS NULL THEN t2.drinkpreferences WHEN t2.drinkpreferences IS NULL THEN t1.drinkpreferences
ELSE t1.drinkpreferences || '/' || t2.drinkpreferences END AS drinkpreferences FROM table1 t1 FULL JOIN table2 t2 ON t1.id = t2.id
Achievable using multiple unions and joins.
select distinct FirstName, LastName, case when ct = 2 then 'Coke/Pepsi' else DrinkPreference end
from (
select FirstName, LastName, DrinkPreference, Id from table1
union all
select FirstName, LastName, DrinkPreference, Id from table2) a
left join
(
select count(1)ct, Id from
(select Id from table1
union all
select Id from table2) t1
group by Id
) b on b.Id = a.Id
I have a oracle table which is similar to the one below which stores people's lastname firstname and age. If last name is same people belong to same family.
LastName FirstName Age
===========================
1 miller charls 20
2 miller john 30
3 anderson peter 45
4 Bates andy 50
5 anderson gary 60
6 williams mark 15
I need to write a oracle sql query to
select youngest person from each family. output shd select rows 1,3,4 and 6
How do I do this ?
Another way, a bit shorter:
select lastname
, max(firstname) keep(dense_rank first order by age) as first_name
, max(age) keep(dense_rank first order by age) as age
from you_table_name
group by lastname
order by lastname
Result:
LASTNAME FIRST_NAME AGE
-------- ---------- ----------
Bates andy 50
anderson peter 45
miller charls 20
williams mark 15
And SQLFiddle Demo
DENSE_RANK() is a ranking function which generates sequential number and for ties the number generated is the same. I prefer to use DENSE_RANK() here considering that a family can have twins, etc.
SELECT Lastname, FirstName, Age
FROM
(
SELECT Lastname, FirstName, Age,
DENSE_RANK() OVER (PARTITION BY LastName ORDER BY Age) rn
FROM tableName
) a
WHERE a.rn = 1
SQLFiddle Demo
With Standard SQL I would do as this...
select *
from family f1
where (
select count(*)
from family f2
where
f2.lastname = f1.lastname
and
f2.age <= f1.age) <= 1
order by lastname;
This SQL gives you possibilities to pick x youngest/oldest in a family. Just modify the f2.age <= f1.age to e.g. f2.age >= f1.age, and the <= 1 to e.g. <=10 (to get top 10 youngest/oldest in a family).
SQLfiddle
I have table where have over 100k information.
ID FirstName
1 Bob
2 Bob
3 Tom
4 John
5 John
6 John
.. ....
Want procedure which will be count how much names are same, For example it must be like :
FirstName Count
Bob 2
Tom 1
John 3
Please help me to write it
It's very basic SQL example, group by column + aggregating results
select
FirstName, count(*)
from Table1
group by FirstName
Try this
select FirstName,Count(FirstName) From TableA group by FirstName
Try this
SELECT FirstName, COUNT(*) As Count
FROM YourTable
GROUP BY FirstName
HAVING COUNT(*) > 1
ORDER BY COUNT(*) DESC
Create Procedure GetCount
as
BEGIN
Select FirstName,Count(*) from tablename group by FirstName
END
If I have the table "members" (shown below), how would I go about getting the record of the first occurrence of a membership_id (Oracle).
Expected results
123 John Doe A P
313 Michael Casey A A
113 Luke Skywalker A P
Table - members
membership_id first_name last_name status type
123 John Doe A P
313 Michael Casey A A
113 Luke Skywalker A P
123 Bob Dole A A
313 Lucas Smith A A
SELECT membership_id,
first_name,
last_name,
status,
type
FROM( SELECT membership_id,
first_name,
last_name,
status,
type,
rank() over (partition by membership_id
order by type desc) rnk
FROM members )
WHERE rnk = 1
will work for your sample data set. If you can have ties-- that is, multiple rows with the same membership_id and the same maximum type-- this query will return all those rows. If you only want to return one of the rows where there is a tie, you would either need to add additional criteria to the order by to ensure that all ties are broken or you would need to use the row_number function rather than rank which will arbitrarily break ties.
Select A.*
FROM Members AS A inner join
(Select membership_id, first(first_name) AS FN, first(last_name) AS LN
From Members
Group by membership_id) AS B
ON A.membership_id=B.membership_id and A.first_name=B.FN and A.last_name=B.LN
Hope that helps!
select *
from members
where rowid in (
select min(rowid)
from members
group by membership_id
)
I have got a table named student. I have written this query:
select * From student where sname in ('rajesh','rohit','rajesh')
In the above query it's returning me two records; one matching 'rajesh' and another matching: 'rohit'.
But i want there to be 3 records: 2 for 'rajesh' and 1 for 'rohit'.
Please provide me some solution or tell me where i am missing.
NOTE: the count of result of sub query is not fix there can be many words there some distinct and some multiple occurrence .
Thanks
Your requirements are not clear, and I'll try to explain why.
Let's define table students
ID FirstName LastName
1 John Smith
2 Mike Smith
3 Ben Bray
4 John Bray
5 John Smith
6 Bill Lynch
7 Bill Smith
Query with WHERE clause:
FirstName in ('Mike', 'Ben', 'Mike')
will return 2 rows only, because it could be rewritten as:
FirstName='Mike' or FirstName='Ben' or FirstName='Mike'
WHERE is filtering clause that just says if existing row satisfy given conditions or not (for each of rows created by FROM clause.
Let's say we have subquery that returns any number of non distinct FirstNames
In case if SQ contains 'Mike', 'Ben', 'Mike' using inner join you can get those 3 rows without problem
Select ST.* from Students ST
Inner Join (Select name from …. <your subquery>) SQ
On ST.FirstName=SQ.name
Result will be:
ID FirstName LastName
2 Mike Smith
2 Mike Smith
3 Ben Bray
Note data are not ordered by order of names returning by SQ. If you want that, SQ should return some ordering number, eg.:
Ord Name
1. Mike
2. Ben
3. Mike
In that case query should be:
Select ST.* from Students ST
Inner Join (Select ord, name from …. <your subquery>) SQ
On ST.FirstName=SQ.name
Order By SQ.ord
And result:
ID FirstName LastName
2 Mike Smith (1)
3 Ben Bray (2)
2 Mike Smith (3)
Now, let's se what will happen if subquery returns
Ord Name
1. Mike
2. Bill
3. Mike
You will end up with
ID FirstName LastName
2 Mike Smith (1)
6 Bill Lynch (2)
7 Bill Smith (2)
2 Mike Smith (3)
Even worse, if you have something like:
Ord Name
1. John
2. Bill
3. John
Result is:
ID FirstName LastName
1 John Smith (1)
4 John Bray (1)
5 John Smith (1)
6 Bill Lynch (2)
7 Bill Smith (2)
1 John Smith (3)
4 John Bray (3)
5 John Smith (3)
This is an complex situation, and you have to clarify precisely what requirement is.
If you need only one student with the same name, for each of rows in SQ, you can use something like SQL 2005+):
;With st1 as
(
Select Row_Number() over (Partition by SQ.ord Order By ID) as rowNum,
ST.ID,
ST.FirstName,
ST.LastName,
SQ.ord
from Students ST
Inner Join (Select ord, name from …. <your subquery>) SQ
On ST.FirstName=SQ.name
)
Select ID, FirstName, LastName
From st1
Where rowNum=1 -- that was missing row, added later
Order By ord
It will return (for SQ values John, Bill, John)
ID FirstName LastName
1 John Smith (1)
6 Bill Lynch (2)
1 John Smith (3)
Note, numbers (1),(2),(3) are shown to display value of ord although they are not returned by query.
If you can split the where clause in your calling code, you could perform a UNION ALL on each clause.
SELECT * FROM Student WHERE sname = 'rajesh'
UNION ALL SELECT * FROM Student WHERE sname = 'rohit'
UNION ALL SELECT * FROM Student WHERE sname = 'rajesh'
Try using a JOIN:
SELECT ...
FROM Student s
INNER JOIN (
SELECT 'rajesh' AS sname
UNION ALL
SELECT 'rohit'
UNION ALL
SELECT 'rajesh') t ON s.sname = t.sname
just because you've got a criteria in there two times doesn't mean that it will return 1 result per criteria. SQL engines usually just use the unique criteria - thus, from your example, there will be 2 criteria in IN clause: 'rajesh','rohit'
WHY do you need to return 2 results? are there two rajesh in your table? they should BOTH return then. You don't need to ask for rajesh twice for that to happen. What does your data look like? What do you want to see returned?
Hi i am query just as you give above and it give me all data that matches in the condition of in clause. just like your post
select * from person
where personid in (
'Carson','Kim','Carson'
)
order by FirstName
and its give me all records which fulfill this Criteria