I need to populate a new column in a table known as RowType, where if the ID column contains the same ID value as the one above RowType is populated with 'D', if the value is new then RowType is populate with 'H', how would the SQL code look to be able to do this?
I.e should look something like below:
RowType (to be populated), ID (already there)
H, 1
D, 1
D, 1
H, 2
D, 2
H, 3
D, 3
D, 3
Thanks
You can use Row_Number and case
select *, RowType = case when Row_Number() over (partition by id order by id) = 1 then 'H' else 'D' End from #yourid
Your input table:
create table #yourId (id int)
insert into #yourid (id) values
(1)
,(1)
,(1)
,(2)
,(2)
,(3)
,(3)
,(3)
Use ROW_NUMER concept :
CREATE TABLE #table(Id INT)
INSERT INTO #table(Id)
SELECT 1 UNION ALL
SELECT 1 UNION ALL
SELECT 1 UNION ALL
SELECT 2 UNION ALL
SELECT 2 UNION ALL
SELECT 3 UNION ALL
SELECT 3 UNION ALL
SELECT 3
SELECT CASE WHEN RowType = 1 THEN 'H' ELSE 'D' END RowType , Id
FROM
(
SELECT ROW_NUMBER() OVER (PARTITION BY Id ORDER BY id) RowType , Id
FROM #table
) A
Please try...
UPDATE tableName
SET RowType = CASE
WHEN ( ID = LAG( ID ) OVER ( ORDER BY ID ) ) THEN 'D'
ELSE 'H'
END
If you have any questions or comments, then please feel free to post a Comment accordingly.
Further Reading
https://learn.microsoft.com/en-us/sql/t-sql/functions/lag-transact-sql (for information on LAG()).
It may not be the best solution, however it can point you somewhere, and it works.
Go through the code carfuly and make sure you understand this.
create table yourTable (RowType char, id int)
insert into yourTable (RowType, id) values
('',1)
,('',1)
,('',1)
,('',2)
,('',2)
,('',3)
,('',3)
,('',3)
select
row_number() over (order by id) as rowNumber,
RowType,
id
into #tempTable
from yourTable
declare #maxRow int = (select max(rowNumber) from #tempTable)
declare #currentRow int = 1
while (#currentRow <= #maxRow)
begin
if (#currentRow = 1)
begin
update #tempTable
set RowType = 'H'
where rowNumber = #currentRow
end
else
begin
if (select id from #tempTable where rowNumber = #currentRow) = (select id from #tempTable where rowNumber = #currentRow - 1)
begin
update #tempTable
set RowType = 'D'
where rowNumber = #currentRow
end
else
begin
update #tempTable
set RowType = 'H'
where rowNumber = #currentRow
end
end
set #currentRow = #currentRow +1
end
-- update data in actual table, you can do below if only those two columns exist in table !!!
delete from yourTable
-- insert into table from updated temp table
insert into yourTable
select RowType, ID
from #tempTable
select * from yourTable
select * from #tempTable
-- drop temp table
drop table #tempTable
Related
declare #varID as INT = 2
insert into table1
(
ID
,varName
)
select
ID
,**#####**
from table2
I want value of varName based on #varID. How can I do that?
What should be in place of #####?
Statement that replicate IF #varname = 2 then 'P' else 'I'.
You are very close. Just mention the variable in the SELECT clause. Like this.
declare #varID as INT = 2
insert into table1 (ID ,varName)
select ID,
CASE WHEN #varID = 2 THEN 'P' ELSE 'I' END
from table2
Maybe a CASE WHEN THEN ELSE END statement like below
declare #varID as INT = 2
insert into table1
(
ID
,varName
)
select
ID
,CASE WHEN #varID=2 THEN 'P' ELSE 'I' END
from table2
I got a simple query which return a results from an OrderLine table. Is there a way to visually separate the query results to make it easier to read, like in the image shown here?
SELECT [OrderNo], [LineNo]
FROM [OrderLine]
Results:
drop table if exists #OrderLine;
select object_id as OrderNo, abs(checksum(newid())) as [LineNo]
into #OrderLine
from sys.columns;
-- ... results to text (ctrl+T)?
select OrderNo, [LineNo],
case when lead(OrderNo, 1) over(partition by OrderNo order by OrderNo) = OrderNo then '' else replicate('-', 11) + char(10) end
from #OrderLine;
--inject NULL
select case when [LineNo] is null and flag=2 then null else TheOrderNo end as OrderNo, [LineNo]
from
(
select OrderNo AS TheOrderNo, [LineNo], 1 as flag
from #OrderLine
union all
select distinct OrderNo, NULL, 2
from #OrderLine
) as src
order by TheOrderNo, flag;
You could execute multiple queries like so:
DECLARE #i int = 1
DECLARE #OrderNo
DECLARE #OrderNos TABLE (
Idx smallint Primary Key IDENTITY(1,1)
, OrderNo int
)
INSERT #OrderNos
SELECT distinct [OrderNo] FROM [OrderLine]
WHILE (#i <= (SELECT MAX(idx) FROM #employee_table))
BEGIN
SET #OrderNo = (SELECT [OrderNo] FROM [OrderNos] WHERE [Idx] = #i)
SELECT [OrderNo], [LineNo]
FROM [OrderLine]
WHERE [OrderNo] = #OrderNo
SET #i = #i + 1
END
You can not directly do that. Perhaps add a new column that is either null or has a value in it so that it is alternating.
Something like this:
select ..., case when rank() over (order by OrderNO) % 2 then 'XXX' else null end
from....
The % 2 is a 'modulo' operator...
Sample data:
create table #temp (id int, qty int, checkvalue int)
insert into #temp values (1,1,3)
insert into #temp values (2,2,3)
insert into #temp values (3,1,3)
insert into #temp values (4,1,3)
According to data above, I would like to show exact number of lines from top to bottom where sum(qty) = checkvalue. Note that checkvalue is same for all the records all the time. Regarding the sample data above, the desired output is:
Id Qty checkValue
1 1 3
2 2 3
Because 1+2=3 and no more data is needed to show. If checkvalue was 4, we would show the third record: Id:3 Qty:1 checkValue:4 as well.
This is the code I am handling this problem. The code is working very well.
declare #checkValue int = (select top 1 checkvalue from #temp);
declare #counter int = 0, #sumValue int = 0;
while #sumValue < #checkValue
begin
set #counter = #counter + 1;
set #sumValue = #sumValue + (
select t.qty from
(
SELECT * FROM (
SELECT
ROW_NUMBER() OVER (ORDER BY id ASC) AS rownumber,
id,qty,checkvalue
FROM #temp
) AS foo
WHERE rownumber = #counter
) t
)
end
declare #sql nvarchar(255) = 'select top '+cast(#counter as varchar(5))+' * from #temp'
EXECUTE sp_executesql #sql, N'#counter int', #counter = #counter;
However, I am not sure if this is the best way to deal with it and wonder if there is a better approach. There are many professionals here and I'd like to hear from them about what they think about my approach and how we can improve it. Any advice would be appreciated!
Try this:
select id, qty, checkvalue from (
select t1.*,
sum(t1.qty) over (partition by t2.id) [sum]
from #temp [t1] join #temp [t2] on t1.id <= t2.id
) a where checkvalue = [sum]
Smart self-join is all you need :)
For SQL Server 2012, and onwards, you can easily achieve this using ROWS BETWEEN in your OVER clause and the use of a CTE:
WITH Running AS(
SELECT *,
SUM(qty) OVER (ORDER BY id
ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS RunningQty
FROM #temp t)
SELECT id, qty, checkvalue
FROM Running
WHERE RunningQty <= checkvalue;
One basic improvement is to try & reduce the no. of iterations. You're incrementing by 1, but if you repurpose the logic behind binary searching, you'd get something close to this:
DECLARE #RoughAverage int = 1 -- Some arbitrary value. The closer it is to the real average, the faster things should be.
DECLARE #CheckValue int = (SELECT TOP 1 checkvalue FROM #temp)
DECLARE #Sum int = 0
WHILE 1 = 1 -- Refer to BREAK below.
BEGIN
SELECT TOP (#RoughAverage) #Sum = SUM(qty) OVER(ORDER BY id)
FROM #temp
ORDER BY id
IF #Sum = #CheckValue
BREAK -- Indicating you reached your objective.
ELSE
SET #RoughAverage = #CheckValue - #Sum -- Most likely incomplete like this.
END
For SQL 2008 you can use recursive cte. Top 1 with ties limits result with first combination. Remove it to see all combinations
with cte as (
select
*, rn = row_number() over (order by id)
from
#temp
)
, rcte as (
select
i = id, id, qty, sumV = qty, checkvalue, rn
from
cte
union all
select
a.id, b.id, b.qty, a.sumV + b.qty, a.checkvalue, b.rn
from
rcte a
join cte b on a.rn + 1 = b.rn
where
a.sumV < b.checkvalue
)
select
top 1 with ties id, qty, checkvalue
from (
select
*, needed = max(case when sumV = checkvalue then 1 else 0 end) over (partition by i)
from
rcte
) t
where
needed = 1
order by dense_rank() over (order by i)
How can I find subsets of data over multiple rows in sql?
I want to count the number of occurrences of a string (or number) before another string is found and then count the number of times this string occurs before another one is found.
All these strings can be in random order.
This is what I want to achieve:
I have one table with one column (columnx) with data like this:
A
A
B
C
A
B
B
The result I want from the query should be like this:
2 A
1 B
1 C
1 A
2 B
Is this even possible in sql or would it be easier just to write a little C# app to do this?
Since, as per your comment, you can add a column that will unambiguously define the order in which the columnx values go, you can try the following query (provided the SQL product you are using supports CTEs and ranking functions):
WITH marked AS (
SELECT
columnx,
sortcolumn,
grp = ROW_NUMBER() OVER ( ORDER BY sortcolumn)
- ROW_NUMBER() OVER (PARTITION BY columnx ORDER BY sortcolumn)
FROM data
)
SELECT
columnx,
COUNT(*)
FROM marked
GROUP BY
columnx,
grp
ORDER BY
MIN(sortcolumn)
;
You can see the method in work on SQL Fiddle.
If sortcolumn is an auto-increment integer column that is guaranteed to have no gaps, you can replace the first ROW_NUMBER() expression with just sortcolumn. But, I guess, that cannot be guaranteed in general. Besides, you might indeed want to sort on a timestamp instead of an integer.
I dont think you can do it with a single select.
You can use AdventureWorks cursor:
create table my_Strings
(
my_string varchar(50)
)
insert into my_strings values('A'),('A'),('B'),('C'),('A'),('B'),('B') -- this method will only work on SQL Server 2008
--select my_String from my_strings
declare #temp_result table(
string varchar(50),
nr int)
declare #myString varchar(50)
declare #myLastString varchar(50)
declare #nr int
set #myLastString='A' --set this with the value of your FIRST string on the table
set #nr=0
DECLARE string_cursor CURSOR
FOR
SELECT my_string as aux_column FROM my_strings
OPEN string_cursor
FETCH NEXT FROM string_cursor into #myString
WHILE ##FETCH_STATUS = 0 BEGIN
if (#myString = #myLastString) begin
set #nr=#nr+1
set #myLastString=#myString
end else begin
insert into #temp_result values (#myLastString, #nr)
set #myLastString=#myString
set #nr=1
end
FETCH NEXT FROM string_cursor into #myString
END
insert into #temp_result values (#myLastString, #nr)
CLOSE string_cursor;
DEALLOCATE string_cursor;
select * from #temp_result
Result:
A 2
B 1
C 1
A 1
B 2
Try this :
;with sample as (
select 'A' as columnx
union all
select 'A'
union all
select 'B'
union all
select 'C'
union all
select 'A'
union all
select 'B'
union all
select 'B'
), data
as (
select columnx,
Row_Number() over(order by (select 0)) id
from sample
) , CTE as (
select * ,
Row_Number() over(order by (select 0)) rno from data
) , result as (
SELECT d.*
, ( SELECT MAX(ID)
FROM CTE c
WHERE NOT EXISTS (SELECT * FROM CTE
WHERE rno = c.rno-1 and columnx = c.columnx)
AND c.ID <= d.ID) AS g
FROM data d
)
SELECT columnx,
COUNT(1) cnt
FROM result
GROUP BY columnx,
g
Result :
columnx cnt
A 2
B 1
C 1
A 1
B 2
Table data look like this
id val
1 4
2 2
3 1
I want result of subtract valu of val field in one sql statement.
like it should be like 4-2-1 = 1 if order by id asc, 1-2-4 = -5 if order by id desc.
You can try this
DECLARE #Table TABLE(
ID INT,
Val INT
)
INSERT INTO #Table (ID,Val) SELECT 1, 4
INSERT INTO #Table (ID,Val) SELECT 2, 2
INSERT INTO #Table (ID,Val) SELECT 3, 1
SELECT SUM(Val * CASE WHEN RowID = 1 THEN 1 ELSE -1 END)
FROM (
SELECT *,
ROW_NUMBER() OVER (ORDER BY ID) RowID
FROM #Table
) sub
You can declare a variable and increment it in the select statement:
declare #sum float
select #sum = case when #sum is null then value else #sum - value end
from YourTable
order by id
select #sum
To reverse the subtraction order, change order by id to order by id desc.
if you want to use just the sql without temp tables or variables:
select fromid.val - sumid.val
from (
select val
from t
where id = (
select min(id)
from t
)
) fromid cross join (
select sum(val) as val
from t
where id > (
select min(id)
from t
)
) sumid