Let's say I have table data similar to the following:
123456 John Doe 1 Green 2001
234567 Jane Doe 1 Yellow 2001
234567 Jane Doe 2 Red 2001
345678 Jim Doe 1 Red 2001
What I am attempting to do is only isolate the records for Jane Doe based upon the fact that she has more than one row in this table. (More that one sequence number)
I cannot isolate based upon ID, names, colors, years, etc...
The number 1 in the sequence tells me that is the first record and I need to be able to display that record, as well as the number 2 record -- The change record.
If the table is called users, and the fields called ID, fname, lname, seq_no, color, date. How would I write the code to select only records that have more than one row in this table? For Example:
I want the query to display this only based upon the existence of the multiple rows:
234567 Jane Doe 1 Yellow 2001
234567 Jane Doe 2 Red 2001
In PL/SQL
First, to find the IDs for records with multiple rows you would use:
SELECT ID FROM table GROUP BY ID HAVING COUNT(*) > 1
So you could get all the records for all those people with
SELECT * FROM table WHERE ID IN (SELECT ID FROM table GROUP BY ID HAVING COUNT(*) > 1)
If you know that the second sequence ID will always be "2" and that the "2" record will never be deleted, you might find something like:
SELECT * FROM table WHERE ID IN (SELECT ID FROM table WHERE SequenceID = 2)
to be faster, but you better be sure the requirements are guaranteed to be met in your database (and you would want a compound index on (SequenceID, ID)).
Try something like the following. It's a single tablescan, as opposed to 2 like the others.
SELECT * FROM (
SELECT t1.*, COUNT(name) OVER (PARTITION BY name) mycount FROM TABLE t1
)
WHERE mycount >1;
INNER JOIN
JOIN:
SELECT u1.ID, u1.fname, u1.lname, u1.seq_no, u1.color, u1.date
FROM users u1 JOIN users u2 ON (u1.ID = u2.ID and u2.seq_no = 2)
WHERE:
SELECT u1.ID, u1.fname, u1.lname, u1.seq_no, u1.color, u1.date
FROM users u1, thetable u2
WHERE
u1.ID = u2.ID AND
u2.seq_no = 2
Check out the HAVING clause for a summary query. You can specify stuff like
HAVING COUNT(*) >= 2
and so forth.
Related
I have a table A that looks similar to:
ID
PET
COUNTRY
45
DOG
US
72
DOG
CA
15
CAT
CA
36
CAT
US
37
CAT
SG
12
SNAKE
IN
20
PIG
US
14
PIG
RS
33
HORSE
IQ
(has about a few hundred rows)
I would like to retain the rows that have a duplicated "PET" value, so the result looks like:
|ID|PET |COUNTRY
|--| --- |---|
|45| DOG |US|
|72 |DOG|CA|
|15 |CAT |CA|
|36 |CAT|US|
|37 |CAT|SG|
|20|PIG|US|
|14|PIG|RS|
How can I remove the rows that do not have duplicated PET values? Would it be something like
SELECT ID, PET, COUNTRY, COUNT(*)
FROM A
GROUP BY PET, COUNTRY, ID
HAVING COUNT(*) >1
I am not sure how to group the values by PET and pick out the groups only containing one row. Thanks!
What about simply doing:
WITH
RES AS (SELECT PET, COUNT(*) FROM A GROUP BY PET HAVING COUNT(*) > 1)
SELECT ID, PET, COUNTRY FROM A WHERE PET IN (SELECT PET FROM RES);
This would give you all rows with pets present in more than one row.
A shorter way is to use QUALIFY:
SELECT *
FROM tab
QUALIFY COUNT(*) OVER(PARTITION BY PET) > 1;
Let's say i have a table structure like this :
ID | Name | SCHOOLNAME | CODESCHOOL
1 DARK Kindergarten 123 1
2 DARK Kindergarten 111 1
3 Knight NY University 3
4 Knight LA Senior HS 2
5 JOHN HARVARD 3
so, how to diplay all of the data above into like this :
ID | Name | SCHOOLNAME | CODESCHOOL
1 DARK Kindergarten 123 1
3 Knight NY University 3
5 JOHN HARVARD 3
my purpose is want to display data with the max of codeschool, but when i tried with my query below :
SELECT NAME, SCHOOLNAME, MAX(CODESCHOOL) FROM TABLE GROUP BY NAME, SCHOOLNAME
but the result is just like this :
ID | Name | SCHOOLNAME | CODESCHOOL
1 DARK Kindergarten 123 1
2 DARK Kindergarten 111 1
3 Knight NY University 3
4 Knight LA Senior HS 2
5 JOHN HARVARD 3
maybe it caused by the GROUP BY SCHOOLNAME, when i tried to not select SCHOOLNAME, the data displayed just like what i expected, but i need the SCHOOLNAME field for search condition in my query
hope you guys can help me out of this problem
any help will be appreciated
thanks
Using some wacky joins you can get a functional get max rows per category query.
What you essentially need to do is to join the table to itself and make sure that the joined values only contain the top values for the CODESCHOOL column.
I've also added a :schoolname parameter because you wanted to search by schoolname
Example:
SELECT
A.*
FROM
TABLE1 A
LEFT OUTER JOIN TABLE1 B ON B.NAME = A.NAME
AND B.CODESCHOOL < A.CODESCHOOL
WHERE
B.CODESCHOOL IS NULL AND
(
(A.SCHOOLNAME = :SCHOOLNAME AND :SCHOOLNAME IS NOT NULL) OR
(:SCHOOLNAME IS NULL)
);
this should create this output, note that dark has 2 outputs because it has 2 rows with the same code school which is the max in the dark "category"/name.
ID|NAME |SCHOOLNAME |CODESCHOOL
--| -----|----------------|----------
4|Knight|LA Senior HS | 2
5|JOHN |HARVARD | 3
2|DARK |Kindergarten 111| 1
1|DARK |Kindergarten 123| 1
It's not the most effective query but it should be more than good enough as a starting point.
Sidenote: I've been blatantly stealing this logic for a while from https://www.xaprb.com/blog/2007/03/14/how-to-find-the-max-row-per-group-in-sql-without-subqueries/
I am using an analytical window function ROW_NUMBER().
This will group (or partition) by NAME then select the top 1 CODESCHOOL in DESC order.
Select NAME,
SCHOOLNAME,
CODESCHOOL
From (
Select NAME,
SCHOOLNAME,
CODESCHOOL,
ROW_NUMBER() OVER (PARTITION BY NAME ORDER BY CODESCHOOL DESC) as rn
from myTable)
Where rn = 1;
Apologies if this seems simple to some, I am still in the (very) early stages of learning!
Basically I've got a table database that has multiple users (Users_ID), each with a corresponding access name(NAME). The problem is, some Users have multiple access names, meaning when the data is pulled, there is duplicates in the User_ID column.
I need to remove the duplicates in the User column and join their corresponding access names in the NAME column, so it only takes up 1 row and no data is lost.
The current SQL query I'm using is :
select Table1_user_id, Table2.name,
from Table1
inner join Table2
on Table1.role_id = Table2.role_id
An example of what this would return:
USER_ID | NAME
------- --------------
Tim Level_1 Access
John Level 2 Access
Tim Level 2 Access
Mark Level 3 Access
Tim Level 3 Access
Ideally, I would remove the duplicates for Tim and display as following:
USER_ID | NAME
------- ----------------------------------------------
Tim Level_1 Access, Level 2 Access, Level 3 Access
John Level 2 Access
Mark Level 3 Access
Thanks in advance for any help regarding this and sorry if something similar has been asked before!
Use GROUP_CONCAT with SEPARATOR :
SELECT Table1.user_id, GROUP_CONCAT(Table2.name SEPARATOR ',') AS Ename
FROM Table1
INNER JOIN Table2 ON Table1.role_id = Table2.role_id
GROUP BY Table1.user_id
select Table1_user_id, LISTAGG(Table2.name,', ') WITHIN GROUP (ORDER BY Table2.name) as Name
from Table1
inner join Table2
on Table1.role_id = Table2.role_id
I am writing a select query with distinct but I am still getting duplicates in my result. The Oracle View do have duplicates and I am trying to get back only 1 occurrence of that value.
Here is my query
select
person.person_id,
person.last_name,
person.first_name,
person.first_name,
person.middle_name,
skill.skills_id,
(case
when trim(skills.skill_description) = 'typing fast' then 'TP1'
when trim(skills.skill_description) = 'courier district 9' then 'CD9'
when trim(skills.skill_description) = 'helpdesk shift 3' then 'HD3'
when trim(skills.skill_description) = 'helpdesk shift 5' then 'HD5'
....
else ''
end) AS skill_description
from person_view person
left join (select distinct person_id, skill_id, skill_description, updated_date
from skill_view) skills
on skills.person_id = person.person_id and
((trunc(sysdate) - PHONE.UPDATED_DT <= 1)) and
trim(skills.skill_description) in ('skill1', 'skill2', 'skill3' ...)
There is a lot of values for skill_description, so I add the IN clause to filter for 15 - 20 specific skill_description values.
My case will take a the value and set the code for it.
I thought when I used the 'distinct' keyword it would filter out the duplicates but it is not working.
Here is my output so far
105 John E Doe SKILL1
105 John E Doe SKILL1
105 John E Doe SKILL2
105 John E Doe SKILL2
105 John E Doe SKILL3
105 John E Doe SKILL3
Any help is appreciated. Thanks
The problem is the DISTINCT is in an inner level and maybe the duplicates are outside the LEFT JOIN, you must put the DISTINCT clause in the first SELECT.
This should give you the desire output:
SELECT DISTINCT
person.person_id,
person.last_name,
person.first_name,
person.first_name,
person.middle_name,
skill.skills_id,
OMMITED CODE...
You are selecting updated_date in the subquery, but you don't use it in the outer query. QUESTION: Why? Did you mean to use it for something, perhaps to only select the most current info from the table?
In any case, if you have the same person_id, skill_id and skill_description values but different updated_date, DISTINCT won't help; the rows may very well be distinct in the inner query, but cease to be distinct in the outer query (if you don't include updated_date in the projection).
Using Oracle Application Express and I want to display each duplicate entry in a table. I also want to create a column with a value of 1 for each instance of a duplicate.
So with a table:
Name
Chris
Sean
Chris
John
My query should return
Name Count
Chris 1
Chris 1
How would I do this?
You can do this using window/analytic functions:
select name, 1
from (select name, count(*) over (partition by name) as cnt
from table t
) t
where cnt > 1;