I need, if possible, a t-sql query that, returning the values from an arbitrary table, also returns a incremental integer column with value = 1 for the first row, 2 for the second, and so on.
This column does not actually resides in any table, and must be strictly incremental, because the ORDER BY clause could sort the rows of the table and I want the incremental row in perfect shape always.
The solution must run on SQL Server 2000
For SQL 2005 and up
SELECT ROW_NUMBER() OVER( ORDER BY SomeColumn ) AS 'rownumber',*
FROM YourTable
for 2000 you need to do something like this
SELECT IDENTITY(INT, 1,1) AS Rank ,VALUE
INTO #Ranks FROM YourTable WHERE 1=0
INSERT INTO #Ranks
SELECT SomeColumn FROM YourTable
ORDER BY SomeColumn
SELECT * FROM #Ranks
Order By Ranks
see also here Row Number
You can start with a custom number and increment from there, for example you want to add a cheque number for each payment you can do:
select #StartChequeNumber = 3446;
SELECT
((ROW_NUMBER() OVER(ORDER BY AnyColumn)) + #StartChequeNumber ) AS 'ChequeNumber'
,* FROM YourTable
will give the correct cheque number for each row.
Try ROW_NUMBER()
http://msdn.microsoft.com/en-us/library/ms186734.aspx
Example:
SELECT
col1,
col2,
ROW_NUMBER() OVER (ORDER BY col1) AS rownum
FROM tbl
It is ugly and performs badly, but technically this works on any table with at least one unique field AND works in SQL 2000.
SELECT (SELECT COUNT(*) FROM myTable T1 WHERE T1.UniqueField<=T2.UniqueField) as RowNum, T2.OtherField
FROM myTable T2
ORDER By T2.UniqueField
Note: If you use this approach and add a WHERE clause to the outer SELECT, you have to added it to the inner SELECT also if you want the numbers to be continuous.
Related
I need to calculate the difference of a column between two lines of a table. Is there any way I can do this directly in SQL? I'm using Microsoft SQL Server 2008.
I'm looking for something like this:
SELECT value - (previous.value) FROM table
Imagining that the "previous" variable reference the latest selected row. Of course with a select like that I will end up with n-1 rows selected in a table with n rows, that's not a probably, actually is exactly what I need.
Is that possible in some way?
Use the lag function:
SELECT value - lag(value) OVER (ORDER BY Id) FROM table
Sequences used for Ids can skip values, so Id-1 does not always work.
SQL has no built in notion of order, so you need to order by some column for this to be meaningful. Something like this:
select t1.value - t2.value from table t1, table t2
where t1.primaryKey = t2.primaryKey - 1
If you know how to order things but not how to get the previous value given the current one (EG, you want to order alphabetically) then I don't know of a way to do that in standard SQL, but most SQL implementations will have extensions to do it.
Here is a way for SQL server that works if you can order rows such that each one is distinct:
select rank() OVER (ORDER BY id) as 'Rank', value into temp1 from t
select t1.value - t2.value from temp1 t1, temp1 t2
where t1.Rank = t2.Rank - 1
drop table temp1
If you need to break ties, you can add as many columns as necessary to the ORDER BY.
WITH CTE AS (
SELECT
rownum = ROW_NUMBER() OVER (ORDER BY columns_to_order_by),
value
FROM table
)
SELECT
curr.value - prev.value
FROM CTE cur
INNER JOIN CTE prev on prev.rownum = cur.rownum - 1
Oracle, PostgreSQL, SQL Server and many more RDBMS engines have analytic functions called LAG and LEAD that do this very thing.
In SQL Server prior to 2012 you'd need to do the following:
SELECT value - (
SELECT TOP 1 value
FROM mytable m2
WHERE m2.col1 < m1.col1 OR (m2.col1 = m1.col1 AND m2.pk < m1.pk)
ORDER BY
col1, pk
)
FROM mytable m1
ORDER BY
col1, pk
, where COL1 is the column you are ordering by.
Having an index on (COL1, PK) will greatly improve this query.
LEFT JOIN the table to itself, with the join condition worked out so the row matched in the joined version of the table is one row previous, for your particular definition of "previous".
Update: At first I was thinking you would want to keep all rows, with NULLs for the condition where there was no previous row. Reading it again you just want that rows culled, so you should an inner join rather than a left join.
Update:
Newer versions of Sql Server also have the LAG and LEAD Windowing functions that can be used for this, too.
select t2.col from (
select col,MAX(ID) id from
(
select ROW_NUMBER() over(PARTITION by col order by col) id ,col from testtab t1) as t1
group by col) as t2
The selected answer will only work if there are no gaps in the sequence. However if you are using an autogenerated id, there are likely to be gaps in the sequence due to inserts that were rolled back.
This method should work if you have gaps
declare #temp (value int, primaryKey int, tempid int identity)
insert value, primarykey from mytable order by primarykey
select t1.value - t2.value from #temp t1
join #temp t2
on t1.tempid = t2.tempid - 1
Another way to refer to the previous row in an SQL query is to use a recursive common table expression (CTE):
CREATE TABLE t (counter INTEGER);
INSERT INTO t VALUES (1),(2),(3),(4),(5);
WITH cte(counter, previous, difference) AS (
-- Anchor query
SELECT MIN(counter), 0, MIN(counter)
FROM t
UNION ALL
-- Recursive query
SELECT t.counter, cte.counter, t.counter - cte.counter
FROM t JOIN cte ON cte.counter = t.counter - 1
)
SELECT counter, previous, difference
FROM cte
ORDER BY counter;
Result:
counter
previous
difference
1
0
1
2
1
1
3
2
1
4
3
1
5
4
1
The anchor query generates the first row of the common table expression cte where it sets cte.counter to column t.counter in the first row of table t, cte.previous to 0, and cte.difference to the first row of t.counter.
The recursive query joins each row of common table expression cte to the previous row of table t. In the recursive query, cte.counter refers to t.counter in each row of table t, cte.previous refers to cte.counter in the previous row of cte, and t.counter - cte.counter refers to the difference between these two columns.
Note that a recursive CTE is more flexible than the LAG and LEAD functions because a row can refer to any arbitrary result of a previous row. (A recursive function or process is one where the input of the process is the output of the previous iteration of that process, except the first input which is a constant.)
I tested this query at SQLite Online.
You can use the following funtion to get current row value and previous row value:
SELECT value,
min(value) over (order by id rows between 1 preceding and 1
preceding) as value_prev
FROM table
Then you can just select value - value_prev from that select and get your answer
I was wondering is there a way to retrieve, for example, 2nd and 5th row from SQL table that contains 100 rows?
I saw some solutions with WHERE clause but they all assume that the column on which WHERE clause is applied is linear, starting at 1.
Is there other way to query a SQL Server table for a specific rows in case table doesn't have a column whose values start at 1?
P.S. - I know for a solution with temporary tables, where you copy your select statement output and add a linear column to the table. I am using T-SQL
Try this,
SELECT * FROM (
SELECT
ROW_NUMBER() OVER (ORDER BY ColumnName ASC) AS rownumber
FROM TableName
) as temptablename
WHERE rownumber IN (2,5)
With SQL Server:
; WITH Base AS (
SELECT *, ROW_NUMBER() OVER (ORDER BY id) RN FROM YourTable
)
SELECT *
FROM Base WHERE RN IN (2, 5)
The id that you'll have to replace with your primary key or your ordering, YourTable that is your table.
It's a CTE (Common Table Expression) so it isn't a temporary table. It's something that will be expanded together with your query.
There is no 2nd or 5th row in the table.
There is only the 2nd or 5th result in a resultset that you return, as determined by the order you specify in that query.
If you are on SQL Server 2005 or above, you could use Row_Number() function. Ex:
;With CTE as (
select col1, ..., row_number() over (order by yourOrderingCol) rn
from yourTable
)
select col1,...
from cte
where rn in (2,5)
Please note that yourOrderingCol will decide the value of row number (i.e. rn).
I want to pull all rows except the last one in Oracle SQL
My database is like this
Prikey - Auto_increment
common - varchar
miles - int
So I want to sum all rows except the last row ordered by primary key grouped by common. That means for each distinct common, the miles will be summed (except for the last one)
Note: the question was changed after this answer was posted. The first two queries work for the original question. The last query (in the addendum) works for the updated question.
This should do the trick, though it will be a bit slow for larger tables:
SELECT prikey, authnum FROM myTable
WHERE prikey <> (SELECT MAX(prikey) FROM myTable)
ORDER BY prikey
This query is longer but for a large table it should faster. I'll leave it to you to decide:
SELECT * FROM (
SELECT
prikey,
authnum,
ROW_NUMBER() OVER (ORDER BY prikey DESC) AS RowRank
FROM myTable)
WHERE RowRank <> 1
ORDER BY prikey
Addendum There was an update to the question; here's the updated answer.
SELECT
common,
SUM(miles)
FROM (
SELECT
common,
miles,
ROW_NUMBER() OVER (PARTITION BY common ORDER BY prikey DESC) AS RowRank
FROM myTable
)
WHERE RowRank <> 1
GROUP BY common
Looks like I am a little too late but here is my contribution, similar to Ed Gibbs' first solution but instead of calculating the max id for each value in the table and then comparing I get it once using an inline view.
SELECT d1.prikey,
d1.authnum
FROM myTable d1,
(SELECT MAX(prikey) prikey myTable FROM myTable) d2
WHERE d1.prikey != d2.prikey
At least I think this is more efficient if you want to go without the use of Analytics.
query to retrieve all the records in the table except first row and last row
select * from table_name
where primary_id_column not in
(
select top 1 * from table_name order by primary_id_column asc
)
and
primary_id_column not in
(
select top 1 * from table_name order by primary_id_column desc
)
I'm looking to some expresion like this (using SQL Server 2008)
SELECT TOP 10 columName FROM tableName
But instead of that I need the values between 10 and 20. And I wonder if there is a way of doing it using only one SELECT statement.
For example this is useless:
SELECT columName FROM
(SELECT ROW_NUMBER() OVER(ORDER BY someId) AS RowNum, * FROM tableName) AS alias
WHERE RowNum BETWEEN 10 AND 20
Because the select inside brackets is already returning all the results, and I'm looking to avoid that, due to performance.
Use SQL Server 2012 to fetch/skip!
SELECT SalesOrderID, SalesOrderDetailID, ProductID, OrderQty, UnitPrice, LineTotal
FROM AdventureWorks2012.Sales.SalesOrderDetail
OFFSET 10 ROWS FETCH NEXT 10 ROWS ONLY;
There's nothing better than you're describing for older versions of sql server. Maybe use CTE, but unlikely to make a difference.
WITH NumberedMyTable AS
(
SELECT
Id,
Value,
ROW_NUMBER() OVER (ORDER BY Id) AS RowNumber
FROM
MyTable
)
SELECT
Id,
Value
FROM
NumberedMyTable
WHERE
RowNumber BETWEEN #From AND #To
or, you can remove top 10 rows and then get next 10 rows, but I double anyone would want to do that.
There is a trick with row_number that does not involve sorting all the rows.
Try this:
SELECT columName
FROM (SELECT ROW_NUMBER() OVER(ORDER BY (select NULL as noorder)) AS RowNum, *
FROM tableName
) as alias
WHERE RowNum BETWEEN 10 AND 20
You cannot use a constant in the order by. However, you can use an expression that evaluates to a constant. SQL Server recognizes this and just returns the rows as encountered, properly enumerated.
Why do you think SQL Server would evaluate the entire inner query? Assuming your sort column is indexed, it'll just read the first 20 values. If you're really nervous you could do this:
Select
Id
From (
Select Top 20 -- note top 20
Row_Number() Over(Order By Id) As RowNum,
Id
From
dbo.Test
Order By
Id
) As alias
Where
RowNum Between 10 And 20
Order By
Id
but I'm pretty sure the query plan is the same either way.
(Really) Fixed as per Aaron's comment.
http://sqlfiddle.com/#!3/db162/6
One more option
SELECT TOP(11) columName
FROM dbo.tableName
ORDER BY
CASE WHEN ROW_NUMBER() OVER (ORDER BY someId) BETWEEN 10 AND 20
THEN ROW_NUMBER() OVER (ORDER BY someId) ELSE NULL END DESC
You could create a temp table that is ordered the way you want like:
SELECT ROW_NUMBER() OVER(ORDER BY someId) AS RowNum, * FROM tableName
into ##tempTable
...
That way you have an ordered list of rows.
and can just query by row number the subsequent times instead of doing the inner query multiple times.
I need to calculate the difference of a column between two lines of a table. Is there any way I can do this directly in SQL? I'm using Microsoft SQL Server 2008.
I'm looking for something like this:
SELECT value - (previous.value) FROM table
Imagining that the "previous" variable reference the latest selected row. Of course with a select like that I will end up with n-1 rows selected in a table with n rows, that's not a probably, actually is exactly what I need.
Is that possible in some way?
Use the lag function:
SELECT value - lag(value) OVER (ORDER BY Id) FROM table
Sequences used for Ids can skip values, so Id-1 does not always work.
SQL has no built in notion of order, so you need to order by some column for this to be meaningful. Something like this:
select t1.value - t2.value from table t1, table t2
where t1.primaryKey = t2.primaryKey - 1
If you know how to order things but not how to get the previous value given the current one (EG, you want to order alphabetically) then I don't know of a way to do that in standard SQL, but most SQL implementations will have extensions to do it.
Here is a way for SQL server that works if you can order rows such that each one is distinct:
select rank() OVER (ORDER BY id) as 'Rank', value into temp1 from t
select t1.value - t2.value from temp1 t1, temp1 t2
where t1.Rank = t2.Rank - 1
drop table temp1
If you need to break ties, you can add as many columns as necessary to the ORDER BY.
WITH CTE AS (
SELECT
rownum = ROW_NUMBER() OVER (ORDER BY columns_to_order_by),
value
FROM table
)
SELECT
curr.value - prev.value
FROM CTE cur
INNER JOIN CTE prev on prev.rownum = cur.rownum - 1
Oracle, PostgreSQL, SQL Server and many more RDBMS engines have analytic functions called LAG and LEAD that do this very thing.
In SQL Server prior to 2012 you'd need to do the following:
SELECT value - (
SELECT TOP 1 value
FROM mytable m2
WHERE m2.col1 < m1.col1 OR (m2.col1 = m1.col1 AND m2.pk < m1.pk)
ORDER BY
col1, pk
)
FROM mytable m1
ORDER BY
col1, pk
, where COL1 is the column you are ordering by.
Having an index on (COL1, PK) will greatly improve this query.
LEFT JOIN the table to itself, with the join condition worked out so the row matched in the joined version of the table is one row previous, for your particular definition of "previous".
Update: At first I was thinking you would want to keep all rows, with NULLs for the condition where there was no previous row. Reading it again you just want that rows culled, so you should an inner join rather than a left join.
Update:
Newer versions of Sql Server also have the LAG and LEAD Windowing functions that can be used for this, too.
select t2.col from (
select col,MAX(ID) id from
(
select ROW_NUMBER() over(PARTITION by col order by col) id ,col from testtab t1) as t1
group by col) as t2
The selected answer will only work if there are no gaps in the sequence. However if you are using an autogenerated id, there are likely to be gaps in the sequence due to inserts that were rolled back.
This method should work if you have gaps
declare #temp (value int, primaryKey int, tempid int identity)
insert value, primarykey from mytable order by primarykey
select t1.value - t2.value from #temp t1
join #temp t2
on t1.tempid = t2.tempid - 1
Another way to refer to the previous row in an SQL query is to use a recursive common table expression (CTE):
CREATE TABLE t (counter INTEGER);
INSERT INTO t VALUES (1),(2),(3),(4),(5);
WITH cte(counter, previous, difference) AS (
-- Anchor query
SELECT MIN(counter), 0, MIN(counter)
FROM t
UNION ALL
-- Recursive query
SELECT t.counter, cte.counter, t.counter - cte.counter
FROM t JOIN cte ON cte.counter = t.counter - 1
)
SELECT counter, previous, difference
FROM cte
ORDER BY counter;
Result:
counter
previous
difference
1
0
1
2
1
1
3
2
1
4
3
1
5
4
1
The anchor query generates the first row of the common table expression cte where it sets cte.counter to column t.counter in the first row of table t, cte.previous to 0, and cte.difference to the first row of t.counter.
The recursive query joins each row of common table expression cte to the previous row of table t. In the recursive query, cte.counter refers to t.counter in each row of table t, cte.previous refers to cte.counter in the previous row of cte, and t.counter - cte.counter refers to the difference between these two columns.
Note that a recursive CTE is more flexible than the LAG and LEAD functions because a row can refer to any arbitrary result of a previous row. (A recursive function or process is one where the input of the process is the output of the previous iteration of that process, except the first input which is a constant.)
I tested this query at SQLite Online.
You can use the following funtion to get current row value and previous row value:
SELECT value,
min(value) over (order by id rows between 1 preceding and 1
preceding) as value_prev
FROM table
Then you can just select value - value_prev from that select and get your answer