I have a SQL query which displays a list of results. Every row in my database has about
20 columns and not every column is mandatory. I would like the result of the SQL query to be
sorted by the number of filled in columns. The rows with the least empty columns at the top, the ones with the most empty columns at the bottom. Do any of you guys have an idea how to do this?
I thought about adding an extra column to the table which if updated every time the user edits their row, this number would indicate the number of empty columns and I could sort my list with that. This however, sounds like unnecessary troubles, but maybe there is no other way? I'm sure somebody on here will know!
Thanks,
Sander
You can do it in just about any database with a giant case statement:
order by ((case when col1 is not null then 1 else 0 end) +
(case when col2 is not null then 1 else 0 end) +
. . .
(case when col20 is not null then 1 else 0 end)
) desc
You could order by the amount of empty columns:
order by
case when col1 is null then 1 else 0 end +
case when col2 is null then 1 else 0 end +
case when col3 is null then 1 else 0 end +
...
case when col20 is null then 1 else 0 end
(Note the + at the end of the lines: it's only one column with the integer count of empty fields, sorted in ascending order.)
Related
My task is to analyze a big table (250 columns, millions of rows). I need to find out, how many defined values (e.g. -1) there are in each column. I have a solution that loops through the columns of my table and uses the methods described in the following links:
Fastest way to count exact number of rows in a very large table?
https://learn.microsoft.com/de-de/archive/blogs/martijnh/sql-serverhow-to-quickly-retrieve-accurate-row-count-for-table
However, I have to do:
select column into #tab from MyBigTable where column = -1
And then apply the methods to #tab.
Do you see any way how this can be efficiently dealt with?
You could conditionally aggregate
select sum(case when col1 = -1 then 1 else 0 end) col1sum,
sum(case when col2 = -1 then 1 else 0 end) col2sum,
...
...
sum(case when coln = -1 then 1 else 0 end) colnsum
from yourtable
I have table called Numbers in that column I have values from 0 - 10 but I like to keep value of 1-10 only change record of 0 too null
Case numbers
when 0
then ''
but I found this has changed all values and not values that have 0 is there way I can say else leave value as is?
Do you want this?
update t
set number = null
where number = 0;
Or as a select:
select t.*,
(case when number <> 0 then number end)
from t;
SELECT CASE WHEN [column] = 0 THEN NULL ELSE [column] END AS [SomeName]
FROM Numbers
I would like to check if any of my columns in a table have any null values. I am sure there is a quicker way than how I am doing it at the moment. I just want to see if there is a NULL in ANY column however my table has a lot of columns, is there a simple and quick way?
This way I have written so far works but it takes a long time to do for every column (hence the etc etc)
select
sum(case when id is null then 1 else 0 end) as id,
sum(case when name is null then 1 else 0 end) as name,
sum(case when review_count is null then 1 else 0 end) as review_coun,
sum(case when positive_review is null then 1 else 0 end) as
positive_review,
sum(etc etc
from user
I don't know if this will work for your scenario, but it's an option. You can CAST all your columns as a string and then concatenate them together. If you concatenate a NULL value with a string, it will return NULL.
SELECT 'Y'
WHERE EXISTS( -- Check if there are any NULL rows
SELECT
CAST(c1 AS CHAR(1)) ||
CAST(c2 AS CHAR(1)) ||
...
AS MyColumns
WHERE MyColumns IS NULL
)
;
I am looking for a query/set of SQL queries that will give me the record ID of the record which has the "maximum number of non-empty/non-null fields".
I was looking into count() and max() functions, but they seem to be solving problems for the same column, but not for the same row (which is what I am looking for).
Please help.
You could order by the amount of non-empty fields:
select top 1 Record_ID
from YourTable
order by
case when isnull(col1,'') <> '' then 1 else 0 end +
case when isnull(col2,'') <> '' then 1 else 0 end +
case when isnull(col3,'') <> '' then 1 else 0 end +
...
case when isnull(colN,'') <> '' then 1 else 0 end
This is SQL Server syntax. If you're using another database, please amend your question.
I apologize for asking a very vague question but here it is.
I have to write a SQL query in SQL Server as follows.
I have a table say tblA having 10 columns from col1, col2,.....col10.
Each column is not null and definitely holds some value and all of type int.
The query should be to select all such records in which at least 4 columns are matching with given filter criteria, where the filter criteria has values for all 10 columns.
I googled dint get a clue. It needs to be done in SQL server and single query.
Please suggest.
Thanks in advance.
SELECT *
FROM
yourtable
WHERE
case col1 when #value1 then 1 else 0 end +
case col2 when #value2 then 1 else 0 end +
...
case col10 when #value10 then 1 else 0 end
>=4
You can use CASE expressions to determine if four or more columns match:
SELECT *
FROM YourTable
WHERE CASE WHEN Col1 = Filter1 THEN 1 ELSE 0 END +
CASE WHEN Col2 = Filter2 THEN 1 ELSE 0 END +
....
CASE WHEN Col10 = Filter10 THEN 1 ELSE 0 END >= 4
You can do something like this:
select *
from (select t.*,
(case when col1 <whatever> then 1 else 0 end) as col01_matches,
(case when col2 <whatever> then 1 else 0 end) as col02_matches,
. . .
from t
) t
where (col1_matches + col2_matches + col3_matches . . .) >= 4
This creates a separate indicator variable for each match. You could also do the sum in the subquery, in a single variable. I would prefer to have each match separately, just in case the logic gets more complicated or I want to see what matches.