I have a requirement in a report to show alternate colors in row and for this I need to generate sequential numbers in a SQL Select statement (see example below) to use later while displaying rows.
I am trying row_number and some other techniques its not working. This should not be done using script, I should be able to generate within Select statement. Appreciate any help.
RowNumber - 1, Otherdata - Something1
RowNumber - 2, Otherdata - Something2
RowNumber - 3, Otherdata - Something3
RowNumber - 4, Otherdata - Something4
RowNumber - 5, Otherdata - Something5
There is no need to avoid Analytic Functions if your database supports them e.g ROW_NUMBER()
SELECT
ROW_NUMBER() OVER (ORDER BY [<PRIMARYKEY_COLUMN_NAME>]) AS Number
FROM
[<TABLE_NAME>]
The syntax is Func([ arguments ]) OVER (analytic_clause) you need to focus on OVER (). This last parentheses make partition(s) of your rows and apply the Func() on these partitions one by one. In above code we have only single set/partition of rows. Therefore the generated sequence is for all the rows.
You can make multiple set of your data and generate sequence number for each one in a single go. For example if you need generate sequence number for all the set of rows those have same categoryId. You just need to add Partition By clause like this (PARTITION BY categoryId ORDER BY [<PRIMARYKEY_COLUMN_NAME>]).
Remember that after FROM you can also use another extra ORDER BY to sort your data differently. But it has no effect on the OVER ()
If sort column contains unique values, you can also do it without the new built-in Row_Number() function, by using a subquery based on a sort column.
Select [other stuff],
(Select count(*) From table
where sortCol < a.sortCol) rowNum
From table a
Order by sortCol
change < to <= to start counting at 1 instead of 0
Related
I would like to create a row counter with Oracle SQL. This row counter should start from 1 till 5 and then should restart again from 1.
Like:
ORDER, ROW_COUNTER
----- -----------
ORDER1,1
ORDER2,2
ORDER3,3
ORDER4,4
ORDER5,5
ORDER6,1
ORDER7,2
ORDER8,3
ORDER9,4
ORDER10,5
ORDER11,1
ect...
Do you have any idea?
Use row_number() and arithmetics:
select
order_no,
1 + mod(row_number() over(order by order_no) - 1, 5) row_counter
from mytable
This assumes that the first column of the table can be used to order the records, although it would probably make more sense to have something more sensible than a string column (like an autoincremented column for example).
Side note: order is a SQL language keyword (as in: order by), hence not a good choice for a column name. I renamed it to order_no in the query.
SQL tables represent unordered sets. There is no ordering, unless a column specifies the ordering.
But the basic idea is to use row_number() or rownum and some arithmetic:
select t.*,
1 + mod(rownum - 1, 5)
from t;
Note: The results from this are not stable; the table can be read in any order.
Is there a way to count how many times a call ID is repeated in all rows prior to this row or the current field in a SQL query. attached is a sample of the data table.
I guess the simplest solution you want is a RANK() window function. Considering If a row have a rank as 5 means, Same value has occurs previously 4 times in the same column. If your DBMS product supports window function, You may use -
SELECT *, RANK() OVER(PARTITION BY CALLID) - 1
FROM YOUR_TABLE;
This is a very simple question but I can't seem to find documentation on it. How one would query rows by index (ie select the 10th through 20th row in a table)?
I know there's a row_numbers function but it doesn't seem to do what I want.
Do not specify any partition so your row number will be an integer between 1 and your number of record.
SELECT row_num FROM (
SELECT row_number() over () as row_num
FROM your_table
)
WHERE row_num between 100000 and 100010
I seem to have found a roundabout and clunky way of doing this in Athena, so any better answers are welcome. This approach requires you have some numeric column in your table already, in this case named some_numeric_column:
SELECT some_numeric_column, row_num FROM (
SELECT some_numeric_column,
row_number() over (order by some_numeric_column) as row_num
FROM your_table
)
WHERE row_num between 100000 and 100010
To explain, you first select some numeric column in your data, then create a column (called row_num) of row numbers which is based on the order of your selected numeric column. Then you wrap that all in a select call because Athena doesn't support creating and then conditioning on the row_num column within a single call. If you don't wrap it in a second SELECT call Athena will spit out some errors about not finding a column named row_num.
My situation is that a SQL statement which is not predictable, is given to the program and I need to do pagination on top of it. The final SQL statement would be similar to the following one:
SELECT * FROM (*Given SQL Statement*) b
OFFSET 0 ROWS FETCH NEXT 50 ROWS ONLY;
The problem here is that the *Given SQL Statement* is unpredictable. It may or may not contain order by clause. I am not able to change the query result of this SQL Statement and I need to do pagination on it.
I searched for solution on the Internet, but all of them suggested to use an arbitrary column, like primary key, in order by clause. But it will change the original order.
The short answer is that it can't be done, or at least can't be done properly.
The problem is that SQL Server (or any RDBMS) does not and can not guarantee the order of the records returned from a query without an order by clause.
This means that you can't use paging on such queries.
Further more, if you use an order by clause on a column that appears multiple times in your resultset, the order of the result set is still not guaranteed inside groups of values in said column - quick example:
;WITH cte (a, b)
AS
(
SELECT 1, 'a'
UNION ALL
SELECT 1, 'b'
UNION ALL
SELECT 2, 'a'
UNION ALL
SELECT 2, 'b'
)
SELECT *
FROM cte
ORDER BY a
Both result sets are valid, and you can't know in advance what will you get:
a b
-----
1 b
1 a
2 b
2 a
a b
-----
1 a
1 b
2 a
2 b
(and of course, you might get other sorts)
The problem here is that the *Given SQL Statement" is unpredictable. It may or may not contain order by clause.
your inner query(unpredictable sql statement) should not contain order by,even if it contains,order is not guaranteed.
To get guaranteed order,you have to order by some column.for the results to be deterministic,the ordered column/columns should be unique
Please note: what I'm about to suggest is probably horribly inefficient and should really only be used to help you go back to the project leader and tell them that pagination of an unordered query should not be done. Having said that...
From your comments you say you are able to change the SQL statement before it is executed.
You could write the results of the original query to a temporary table, adding row count field to be used for subsequent pagination ordering.
Therefore any original ordering is preserved and you can now paginate.
But of course the reason for needing pagination in the first place is to avoid sending large amounts of data to the client application. Although this does prevent that, you will still be copying data to a temp table which, depending on the row size and count, could be very slow.
You also have the problem that the page size is coming from the client as part of the SQL statement. Parsing the statement to pick that out could be tricky.
As other notified using anyway without using a sorted query will not be safe, But as you know about it and search about it, I can suggest using a query like this (But not recommended as a good way)
;with cte as (
select *,
row_number() over (order by (select 0)) rn
from (
-- Your query
) t
)
select *
from cte
where rn between (#pageNumber-1)*#pageSize+1 and #pageNumber*#pageSize
[SQL Fiddle Demo]
I finally found a simple way to do it without any order by on a specific column:
declare #start AS INTEGER = 1, #count AS INTEGER = 5;
select * from (SELECT *,ROW_NUMBER() OVER (ORDER BY (SELECT 1)) AS fakeCounter
FROM (select * from mytable) AS t) AS t2 order by fakeCounter OFFSET #start ROWS
FETCH NEXT #count ROWS ONLY
where select * from mytable can be any query
I want to insert sequential numbers into a single column.
The columns have been set to NULL
Is there a command I can now use to populate just that column with sequential numbers
Thanks
you can use row_number analytic function to generate sequence number, that can be used to update the values.
WITH cte
AS
( SELECT ROW_NUMBER() OVER ( ORDER BY (SELECT null)) as rn , column1
FROM table1
)
UPDATE cte
SET column1 = rn
Based on your comment:
that almost did it but it would be nice if we can get it to sequence
properly for instance like 0000001, 0000002,0000003 etc up to 7
characters
I think this is what you are trying to do:
SELECT RIGHT('0000000' + CONVERT(VARCHAR, ROW_NUMBER() OVER ( ORDER BY COLUMN_NAME)), 7) AS ROW_NUM
FROM TABLE_NAME
Update after comment:
Basically this is what I am trying to do. I will be running a query to
grab those 7 character ID from that ALTATH column that will be used as
Reference ID so the column should have those output or type in
it..hope that's clear...thanks
I would personally use an Identity column and format the output when selecting records like this:
SELECT RIGHT('0000000' + CONVERT(VARCHAR, ID_COLUMN), 7) AS ROW_NUM
FROM TABLE_NAME
If you use the analytical functions the ROW_NUM column will not be the same everytime. If you use Identity SQL Server will take care of assigning the numbers in sequence for you. That is the DBMS's job.