I am writing a program in SQL, but every time I execute the program in MSSMS, there is a column on the far left that contains row numbers. I would like to call the the row numbers in this column in a while statement I am using in the same program, but I'm not sure how to refer to it in the code. What is this column called so that I can call it and get the row numbers?
The column to which you are referring is generated by SQL Server and does not actually exist in your result set. If there exists one or more columns in your table which would generate that ordering, then you may add a call to ROW_NUMBER to obtain that column you are seeing. For example:
SELECT *, ROW_NUMBER() OVER (ORDER BY some_col) rn
FROM yourTable
ORDER BY rn;
You can add your own row numbers using row_number():
select row_number() over (order by <order cols>) as seqnum,
. . .
from t
order by <order cols>;
These are in the data and can be referenced in subsequent processing.
Related
I am trying to perform ranking based on some calculation of already existing columns. I tried using the SQL RANK() function however it is showing the result as 1 for all entries even if the value of the order by (score column) is different. Please see the details below:
qu_point and ti_points are calculated columns
score column is again a derived column, however, simply sum of two columns mentioned in point 1.
I have used the SQL query as follow:
use EFR_DB
GO
select d.serial, d.question_set_id, d.correct_answers, d.total_questions, d.time_taken_seconds, q.total_time_in_secs,
(cast(d.correct_answers as float)/d.total_questions) as qu_point, ((q.total_time_in_secs-d.time_taken_seconds)/q.total_time_in_secs) as ti_point,
(((cast(d.correct_answers as float)/d.total_questions)*2) + ((q.total_time_in_secs-d.time_taken_seconds)/q.total_time_in_secs)) as score,
rank() over (partition by d.question_set_id order by score)
from daily_quiz_record d join Question_set q
on q.question_set_id=d.question_set_id
Please help me how can I do the raking which is partitioned by question_set_id and ranked on the basis of the score.
Screenshot attached for your reference.
enter image description here
You can’t use an alias defined in the select clause in the same clause. I suppose that one of your table has a column called score, otherwise your query would error - so this existing column is being used for ordering instead of the computed value.
Since your expression is lengthy, it is simpler to turn the query to a subquery, and rank in the outer query:
select
t.*,
rank() over(partition by question_set_id order by score) rn
from (
-- your existing query (without rank)
) t
I am looking for a way to update records so each entry adds 1 to the end of the string. In my case, I'm trying to update a field named FiberID. Each Record should have JCK0.R000.Ax, where x is equal to 1,2,3...,24.
Ideal result:
FiberID
JCK0.R000.A1
JCK0.R000.A2
JCK0.R000.A3
... and so on until it reaches A24.
Here is an example of the data.
This seems so useful that I'm sure it has been discussed here before, but for what ever reason I'm not seeing anything.
You could use an row_number and an updatable CTE:
with cte as (
select
fiber_id,
concat(
fiber_id,
'.A',
cast(row_number() over (partition by fiber_id order by id) as varchar(2))
) new_fiber_id
from mytable
)
update cte set fiber_id = new_fiber_id
This assumes that you have a column called id that can be used to order records having the same fiber_id.
Side note: it is unclear why you should have exactly 24 numbers per fiber_id, and you sample data does not describes that. This will assign increasing numbers to duplicate fiber_ids, regardless of how many there are.
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 query is to avoid duplicate in a particular column while selecting all columns. But DISTINCT is not working since seq.number column is also being selected.
Any idea to make the query work
In the below example query seq_num is unique key.
Edit: including sample data in picture
select DISTINCT(name), seq_num from table_1;
For two columns this query will be enough:
SELECT name, min(seq_num)
FROM table
GROUP BY name
For more column, use row_number analytic functon
SELECT name, col1, col2, .... col500, seq_num
FROM (
SELECT t.*, row_number() over (partition by name order by seq_num ) As rn
FROM table t
)
WHERE rn = 1
The above queries pick only one row with a given name and the smallest seq_num value for each name.
You cannot do what you want. Please read more about DISTINCT clause and query result set. You will understand that distinct is not suitable for your issue. If you provide some sample data for what you have and what should query show, when possible we will help you.
How do I select a particular row from sql table. Example if value of variable is 2, then select 2nd row from table?
Is there any function in VBS to determine how many rows are in the table?
How do I select a particular row from sql table. Example if value of variable is 2, then select 2nd row from table?
You can execute the following SQL, that uses the RANK() SQL Server function to always get the second row, for example, by ordering the records by id column in DESC order:
SELECT * FROM
(
SELECT *, RANK() OVER (ORDER BY id DESC) 'RowRank' FROM MyTable
) AS A
WHERE RowRank = 2
Is there any function in VBS to determine how many rows are in the table?
I am not sure if VBS has out-of-the-box function to get the number of rows in a table, but you can use a simple SQL query to find that out:
SELECT COUNT(*) FROM MyTable
This would return a value, but the query above that is selecting the second row would return a list of column values, as present in the table.