i want to say
select col1,col2,col3
from table1
inner join table2 on table1.col1=table2.col1
and ..... ( ? )
? : i want just 1 record or first record from table1 joined with first record from table2. but the command cause all record joined that can be join. for example if 2 records are in the table1 that col1=1432 and just 1 record in table2 exists that col1=1432 command joined all. but i want to join just first from table1 with first from table2
i want to display all record that are more than 1 record to be join.
i want just 1 record or first record from table1 joined with first
record from table2
Here you go:
select top 1 col1,col2,col3
from table1
inner join table2 on table1.col1=table2.col1
and .....
Try this query -
SELECT *
FROM dbo.table1 t1
JOIN (
SELECT TOP 1 *
FROM dbo.table2
) t2 ON t1.col1 = t2.col1
If you're on SQL Server 2005 or above, you can try a ranking function to grab only the first record of each group:
select *
from (
select a.col1
, a.col2
, a.col3
-- Use the order by to determine which rows will be ranked first for each group
, row_number() over (partition by a.col1 order by a.col2) as rownum
from table1 as a
join table2 as b on a.col1 = b.col1
) as q
where rownum = 1 -- Only get the first row of each group
i want to display all record that are more than 1 record to be join.
You can add this to your where clause:
and exists (
select col1
from table1
where col1 = q.col1
group by col1
having count(*) > 1
)
To offer another solution that doesn't use a ranking function, I think we would need to know more about your tables, especially unique keys and how you define the first record of each group.
Related
I'm creating 1 temp table (temp1) using table1.
and I want to check if data from temp table is present in table1 and table2.
table1 and table2 have same columns.
It's difficult to assess exactly what you need without further detail, but you could try a LEFT JOIN and a COUNT here to indicate whether there are any matching rows (whereby anything over 0 indicates matching rows)
SELECT
COUNT(*) AS matching_rows
FROM
(
SELECT
1 AS 'ColumnA'
) AS T1
LEFT OUTER JOIN
(
SELECT
2 AS 'ColumnA'
) AS T2
ON T1.ColumnA = T2.ColumnA
WHERE
T2.ColumnA IS NOT NULL
You can also use an INNER JOIN for this:
SELECT
COUNT(*) AS matching_rows
FROM
(
SELECT
1 AS 'ColumnA'
) AS T1
INNER JOIN
(
SELECT
2 AS 'ColumnA'
) AS T2
ON T1.ColumnA = T2.ColumnA
I need to create a table keyed by an ID where the values of one of the columns in the new table are the earliest values entered into the column of another table where the rows share the same ID and have a specific type label.
For example, say I want the Name and first Value entered for each fruit with an entry type A:
These are the tables I have:
TABLE1
Key
ID
Name
1
1
Cherry
2
2
Grape
TABLE2
Key
ID
Value
EntryNum
EntryType
1
1
21
1
A
2
1
32
2
B
3
1
4
3
B
4
1
15
4
A
5
2
3
1
B
6
2
8
2
A
7
2
16
3
B
And this is the result that I want:
TABLE3
ID
Name
EarliestEntry
1
Cherry
21
2
Grape
8
I've attempted the following query but it just returns the same value for all EarliestEntry:
SELECT TABLE1.ID, TABLE2.Name,
(SELECT Value FROM (SELECT ROW_NUMBER() OVER (ORDER BY TABLE2.EntryNum)
as row_num, Value FROM TABLE2
WHERE TABLE2.ID = TABLE1.ID AND TABLE2.EntryType = 'A')
AS sub
WHERE row_num = 1) AS EarliestEntry
INTO TABLE3
FROM TABLE2
INNER JOIN TABLE1 ON TABLE1.ID = TABLE2.ID
GROUP BY TABLE1.ID, TABLE2.Type, TABLE2.EntryNum
I would greatly appreciate help on this. Thank you
If you wanted to use the ROW_NUMBER function then you would need to put that on TABLE1 and add a partition by like so:
WITH rn AS(
SELECT a.Key, ROW_NUMBER() OVER(PARTITION BY a.ID ORDER BY a.EntryNum) AS rn
FROM TABLE2 AS a
)
SELECT b.Name, a.Value AS EarliestValue
FROM TABLE2 AS a
INNER JOIN TABLE1 AS b ON b.ID = a.ID
INNER JOIN rn AS rn ON rn.key = a.key
WHERE rn.rn = 1
In your example you skipped the PARTITION BY clause so you just get a number for all values in TABLE2. Instead of a number per ID in ascending order for Value.
Based on your description of the three tables TABLE1, TABLE2 and TABLE3.
I modified a little bit your script. Thank of Dale K remark, I explain in some words the solution : the field TABLE2.Name shown in the first select was wrong, because [name] belongs to TABLE1, so the right syntax for this is TABLE1.name. And in the GROUP BY clause the field TABLE2.Type might be replaced by TABLE1.name to repect aggregation criteria. So the script becomes :
SELECT DISTINCT table1.id, table1.name,
(SELECT Value FROM (SELECT ROW_NUMBER() OVER (ORDER BY table2.EntryNum)
as row_num, Value FROM table2
WHERE table2.id = table1.id AND table2.EntryType = 'A')
AS sub
WHERE row_num = 1) AS EarliestEntry
INTO table3
FROM table2
INNER JOIN table1 ON table1.id = table2.id
GROUP BY table1.id, table1.name, table2.entrynum;
Here, you can verify the output with fiddle
You are hugely over-complicating this.
Just partition Table2 and take a row-number, then join that to Table1 and filter on only row-number 1
SELECT
t1.Id,
t1.Name,
EarliestEntry = t2.Value
FROM Table1 t1
JOIN (
SELECT *,
rn = ROW_NUMBER() OVER (PARTITION BY t2.ID ORDER BY t2.EntryNum)
FROM Table2 t2
WHERE t2.EntryType = 'A'
) t2 ON t2.ID = t1.ID AND t2.rn = 1;
db<>fiddle
I'm new to mssql .Here am trying to get values from database by joining three tables .
Table 1:
Table 2 :
Here the image there is a possibility for a single user can have multiple image id form this I need to take any one of the image.
Table 3 :
Here am joining the Table 1 and Table 2 by using H_ID
and Table 2 and Table 3 by using IMG_ID.
What I want to do is Need to get all the colum values from Table 1 and Table 2 But the first URL from the Table 3.
In this case an employee has multiple images in the Table I need to take the 1 URL.
Result should be like this :
Query :
SELECT T1.H_ID AS 'ID',
T1.NAME,
T1.ROLE,
T2.SALARY,
T3.IMAGE
FROM TABLE1 T1
JOIN TABLE2 T2
ON T1.H_ID T2.H_ID
JOIN TABLE3 T3
ON T3.IMG_ID = T2.IMG_ID
WHERE T1.STATUS = 'ACTIVE'
Now this query returns 3 rows for the id H_ID = 1001 but It should be a single row.
Can anyone help me to fix this .
use row_number()
with cte as
(SELECT T1.H_ID AS 'ID',T1.NAME,T1.ROLE,T2.SALARY,T3.IMAGE
,row_number() over(partition by T2.img_id order by T3.id) rn
FROM TABLE1 T1
JOIN TABLE2 T2
ON T1.H_ID T2.H_ID
JOIN TABLE3 T3
ON T3.IMG_ID = T2.IMG_ID WHERE T1.STATUS = 'ACTIVE'
) select * from cte where rn=1
After you comments it seems you need subquery
select T1.*,T2.sal,a.url
FROM TABLE1 T1
JOIN TABLE2 T2
ON T1.H_ID T2.H_ID
left join ( select min(id),img_id,url from table3 group by img_id,url) a
on T2.IMG_ID= a.img_id
WHERE T1.STATUS = 'ACTIVE'
I think, You can simply use OUTER APPLY and TOP 1 for that
SELECT T1.H_ID AS 'ID',
T1.NAME,
T1.ROLE,
T2.SALARY,
T3.IMAGE
FROM TABLE1 T1
JOIN TABLE2 T2 ON T1.H_ID T2.H_ID
OUTER APPLY(SELECT TOP 1 T3.IMAGE
FROM TABLE3 T3 WHERE T3.IMG_ID = T2.IMG_ID
--ORDER BY <column_name> --to take top 1 value in specific order
) T3
WHERE T1.STATUS = 'ACTIVE'
I am having trouble finding a suitable query in SQL server. I have department(Table A) having many clients(Table B) data structure. I am looking for a query to retrieve only one client(first occurrence) of each department that the client status is active. any help?
Try like this
SELECT *
FROM Table1 AS T1
WHERE
EXISTS
(
SELECT * FROM Table2 as T2
WHERE T1.Column1 = T2.Column1 AND Column2 = 1
)
AND EXISTS
(
SELECT * FROM Table2 as T2
WHERE T1.Column1 = T2.Column1 AND Column2 = 2
);
You could then try using ROW_NUMBER.
Returns the sequential number of a row within a partition of a result
set, starting at 1 for the first row in each partition.
Something like
;WITH Vals AS (
SELECT d.*,
c.*,
ROW_NUMBER() OVER(PARTITION BY d.departmentid ORDER BY <SOME ORDER FIELDS>) RowID
FROm department d LEFT JOIN
clients c ON <SOME JOIN CONDITION>
AND c.[Status] = 'Active'
)
SELECT *
FROM Vals
WHERE RowID = 1
this is my table layout simplified:
table1: pID (pkey), data
table2: rowID (pkey), pID (fkey), data, date
I want to select some rows from table1 joining one row from table2 per pID for the most recent date for that pID.
I currently do this with the following query:
SELECT * FROM table1 as a
LEFT JOIN table2 AS b ON b.rowID = (SELECT TOP(1) rowID FROM table2 WHERE pID = a.pID ORDER BY date DESC)
This way of working is slow, probabaly because it has to do a subquery on each row of table 1. Is there a way to improve performance on this or do it another way?
You can try something on these lines, use the subquery to get the latest based on the date field (grouping by the pID), then join that with the first table, this way the subquery would not have not have to be executed for each row of Table1 and will result in better performance:
Select *
FROM Table1 a
INNER JOIN
(
SELECT pID, Max(Date) FROM Table2
GROUP BY pID
) b
ON a.pID = b.pID
I have provided the sample SQL for one column using the group by, in case you need additional columns, add them to the GROUP BY clause. Hope this helps.
use the below code, and note that i added the order by Date desc to get the most resent data
select *
from table1 a
inner join table2 b on a.pID=b.pID
where b.rowID in(select top(1) from table2 t where t.pID=a.pID order by Date desc)
I am using the code below in a similar scenaro (I transcripted it to your example)
SELECT b.*
FROM table1 AS a
left outer join (
SELECT a.*
FROM table2 a
inner join (
SELECT a.pID, max(date) as date
FROM table2
WHERE date <= <max_date>
group by pID
) b ON a.pID = b.pID AND a.date = b.date
) b ON a.pID = b.pID
) b on a.pID = b.pID
The only problem with this aproach is that you have to make sure the date's don't reapet for the pID's
You can do this with the row_number() function and a subquery:
SELECT t1.*
FROM table1 t1 LEFT JOIN
(select t2.*, row_number() over (partition by pId order by rowId desc) as seqnum
from table2 t2
) t2
on t1.pId = t2.pId and t2.seqnum = 1;
Use the ROW_NUMBER() function to get a column saying which id of each row in table 2 is the first (As partitioned by the pID, and ordered by the rowDate descending)
Example:
WITH cte AS
(
SELECT
rowID AS t2RowId,
ROW_NUMBER OVER (PARTITION BY pID ORDER BY rowDate DESC) AS rowNum
FROM table2 t2
) -- gets the t2RowIds + a column which says which is the latest for each pID
SELECT t1.*, t2.*
FROM table1 t1
LEFT JOIN
(
table2 t2
JOIN cte ON t2.rowID = cte.t2RowId AND cte.rowNum = 1
) ON t1.pID = t2.pID
This is guaranteed to only return 1 item from table2 per pID, even if multiple items have the same date. You should of course ensure that the date column is indexed in table 2 for quick performance (ideally an index that also covers the PrimaryID of table2)