I need to return one row of data for a parent record. The parent record can have many child records, but I only want the first two rows (and the total count of rows for the parent).
Here is an example of data:
ParentTable
+-----------------------+
| ParentId | ParentData |
+-----------------------+
| 1| Stuff |
| 2| Things |
| 3| Foo |
| 4| Bar |
-------------------------
ChildTable
+-------------------------------+
| ChildId | ParentId| ChildData |
+-------------------------------+
| 1 | 1 | Alpha |
| 2 | 1 | Bravo |
| 3 | 2 | Charlie |
| 4 | 2 | Delta |
| 5 | 2 | Echo |
| 6 | 3 | Foxtrot |
---------------------------------
And here is my desired result:
+-----------------------------------------------------------------+
| ParentId | ParentData | ChildData1 | ChildData2 | ChildRowCount |
+-----------------------------------------------------------------+
| 1 | Stuff | Alpha | Bravo | 2 |
| 2 | Things | Charlie | Delta | 3 |
| 3 | Foo | Foxtrot | (NULL) | 1 |
| 4 | Bar | (NULL) | (NULL) | 0 |
-------------------------------------------------------------------
I'm not sure if this needs a sub-query, a temp table, or a JOIN or GROUP BY of some sort.
In the end I need to use this in SSIS, but I'm starting with a query and going to go from there.
What kind of query can accomplish this?
Use a derived table to number the childdata table's rows and count the number of childid's per parent. left join this to the parenttable and get the desired result.
select distinct p.parentid,p.parentdata,
max(case when c.rnum =1 then c.childata end) over(partition by p.parentid,p.parentdata) as childdata1,
max(case when c.rnum =2 then c.childata end) over(partition by p.parentid,p.parentdata) as childdata2,
coalesce(c.childrowcount,0) as childrowcount
from parenttable p
left join (select c.*
,row_number() over(partition by parentid order by childid) as rnum
,count(*) over(partition by parentid) as childrowcount
from childtable c) c
on c.parentid=p.parentid
Related
I have a table like this in MS SQL SERVER
+------+------+
| ID | Cust |
+------+------+
| 1 | A |
| 1 | A |
| 1 | B |
| 1 | B |
| 2 | A |
| 2 | A |
| 2 | A |
| 2 | B |
| 3 | A |
| 3 | B |
| 3 | B |
| 3 | C |
| 3 | C |
+------+------+
I don't know the values in column "Cust" and I want to return all rows where the value of "Cust" appears multiple times and where at least one of the "ID" values is "1".
Like this:
+------+------+
| ID | Cust |
+------+------+
| 1 | A |
| 1 | A |
| 1 | B |
| 1 | B |
| 2 | A |
| 2 | A |
| 2 | A |
| 2 | B |
| 3 | A |
| 3 | B |
| 3 | B |
+------+------+
Any ideas? I can't find it.
You may use COUNT window function as the following:
SELECT ID, Cust
FROM
(
SELECT ID, Cust,
COUNT(*) OVER (PARTITION BY Cust) cn,
COUNT(CASE WHEN ID=1 THEN 1 END) OVER (PARTITION BY Cust) cn2
FROM table_name
) T
WHERE cn>1 AND cn2>0
ORDER BY ID, Cust
COUNT(*) OVER (PARTITION BY Cust) to check if the value of "Cust" appears multiple times.
COUNT(CASE WHEN ID=1 THEN 1 END) OVER (PARTITION BY Cust) to check that at least one of the "ID" values is "1".
See a demo.
I have table with data as follows
+----+------+
| id | code |
+----+------+
| 1 | M |
| 1 | Y |
| 2 | M |
| 2 | S |
| 3 | M |
| 3 | Q |
+----+------+
I would like to know if its possible to write a query that would return a list of codes that are unique to each ID? If there is no intersection the query should return no rows.
In the example above the only value common to all is M.
+----+------+
| id | code |
+----+------+
| 1 | M |
| 1 | S |
| 2 | M |
| 2 | S |
| 2 | H |
| 3 | M |
| 3 | S |
| 3 | Q |
+----+------+
The above would return M and S, common to all three ID's
Thanks
Try this:
SELECT code
FROM mytable
GROUP BY code
HAVING COUNT(*) = (SELECT COUNT(DISTINCT id) FROM mytable)
The above query assumes that code can appear only once per id.
The database I'm working on is DB2 and I have a problem similar to the following scenario:
Table Structure
-------------------------------
| Teacher Seating Arrangement |
-------------------------------
| PK | seat_argmt_id |
| | teacher_id |
-------------------------------
-----------------------------
| Seating Arrangement |
-----------------------------
|PK FK | seat_argmt_id |
|PK | Row_num |
|PK | seat_num |
|PK | child_name |
-----------------------------
Table Data
------------------------------
| Teacher Seating Arrangement|
------------------------------
| seat_argmt_id | teacher_id |
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 2 |
------------------------------
---------------------------------------------------
| Seating Arrangement |
---------------------------------------------------
| seat_argmt_id | row_num | seat_num | child_name |
| 1 | 1 | 1 | Abe |
| 1 | 1 | 2 | Bob |
| 1 | 1 | 3 | Cat |
| | | | |
| 2 | 1 | 1 | Abe |
| 2 | 1 | 2 | Bob |
| 2 | 1 | 3 | Cat |
| | | | |
| 3 | 1 | 1 | Abe |
| 3 | 1 | 2 | Cat |
| 3 | 1 | 3 | Bob |
| | | | |
| 4 | 1 | 1 | Abe |
| 4 | 1 | 2 | Bob |
| 4 | 1 | 3 | Cat |
| 4 | 2 | 2 | Dan |
---------------------------------------------------
I want to see where there are duplicate seating arrangements for a teacher. And by duplicates I mean where the row_num, seat_num, and child_name are the same among different seat_argmt_id for one teacher_id. So with the data provided above, only seat id 1 and 2 are what I would want to pull back, as they are duplicates on everything but the seat id. If all the children on the 2nd table are exact (sans the primary & foreign key, which is seat_argmt_id in this case), I want to see that.
My initial thought was to do a count(*) group by row#, seat#, and child. Everything with a count of > 1 would mean it's a dupe and = 1 would mean it's unique. That logic only works if you are comparing single rows though. I need to compare multiple rows. I cannot figure out a way to do it via SQL. The solution I have involves going outside of SQL and works (probably). I'm just wondering if there is a way to do it in DB2.
Does this do what you want?
select d.teacher_id, sa.row_num, sa.seat_num, sa.child_name
from seatingarrangement sa join
data d
on sa.seat_argmt_id = d.seat_argmt_id
group by d.teacher_id, sa.row_num, sa.seat_num, sa.child_name
having count(*) > 1;
EDIT:
If you want to find two arrangements that are the same:
select sa1.seat_argmt_id, sa2.seat_argmt_id
from seatingarrangement sa1 join
seatingarrangement sa2
on sa1.seat_argmt_id < sa2.seat_argmt_id and
sa1.row_num = sa2.row_num and
sa1.seat_num = sa2.seat_num and
sa1.child_name = sa2.child_name
group by sa1.seat_argmt_id, sa2.seat_argmt_id
having count(*) = (select count(*) from seatingarrangement sa where sa.seat_argmt_id = sa1.seat_argmt_id) and
count(*) = (select count(*) from seatingarrangement sa where sa.seat_argmt_id = sa2.seat_argmt_id);
This finds the matches between two arrangements and then verifies that the counts are correct.
table: item_tbl
|item_id |serial_code|item_name|
------------------------------
| 1 | x35 | bullet |
| 2 | 6ox | cord |
| 3 | 0hg | cord |
| 4 | a73 | tv |
| 5 | lo5 | bullet |
I tried to use SELECT serial_code, item_name, COUNT(item_name) FROM item_tbl but not what i expected of course. How can I count the distinct values of item_name to have something like:
|serial_code|item_name| count |
-----------------------------
| x35 | bullet | 2 |
| 6ox | cord | 2 |
| 0hg | cord | 2 |
| a73 | tv | 1 |
| lo5 | bullet | 2 |
SELECT Serial_Code, count.Item_Name, Count
FROM
item_tbl i
INNER JOIN
(
SELECT Item_Name, COUNT(1) Count
FROM item_tbl
GROUP BY item_Name
) count ON i.item_Name = count.Item_Name
Lets see if that works.
I have a table with CostCenter_ID (int) and a second table with Process_ID (int).
I'd like to combine the results of both tables so that each cost center ID is assigned to all process IDs, like so:
|CostCenterID | ProcessID |
---------------------------
| 1 | 1 |
| 1 | 2 |
| 1 | 3 |
| 2 | 1 |
| 2 | 2 |
| 2 | 3 |
| 3 | 1 |
| 3 | 2 |
| 3 | 3 |
I've done it before but I'm drawing a blank. I've tried this:
SELECT CostCenter_ID,NULL FROM dbo.Cost_Centers
UNION ALL
SELECT NULL,Process_ID FROM dbo.Processes
which returns this:
|CostCenterID | ProcessID |
---------------------------
| 1 | NULL |
| NULL | 1 |
| NULL | 2 |
| NULL | 3 |
Try:
select a.CostCenterID, b.ProcessID
from table1 a
cross join table2 b
or:
select a.CostCenterID, b.ProcessID
from table1 a
,table2 b
NB: cross join is the better method as it makes it clearer to the reader what your intentions are.
More info (with pics) here: http://www.w3resource.com/sql/joins/cross-join.php