SQL Server or functionality in where condition - sql-server

Question

I have an SQL query where I want to get the rows with values "all" or "female" in [gender] column and value "A" in [group] column. If there are 2 rows with [group] = A and [gender] = all and the other [group] = A and [gender] = female I want to get only the row with [gender] = all. Now I use:
where group=A and (gender=all or gender=female)
But I get both rows
In the example table below I want to get only the row: A all
But if I use the where group=A and (gender=all or gender=female) query I will get both rows for group A
group gender
A all
A female
B all
C female
C all

Answer 1

You can use something like row_number() to prioritize the various subsets of records you're looking at and then select only one record from each. From the wording of your question I assume there is some other field in the table on which you're "grouping" records together—in other words, a field whose every distinct value should produce at most one record in the result set whose group and gender values match your criteria. In the following example I've assumed that this field is called Category; if you share the actual schema of your table then I can improve the example, but this should suffice to illustrate the idea.
declare #SampleData table
(
Category bigint,
[Group] char(1),
Gender varchar(16)
);
insert #SampleData values
(1, 'A', 'Female'), -- include
(2, 'B', 'Female'), -- exclude; wrong group
(3, 'A', 'Female'), -- exclude; right group and gender but superseded by (3, 'A', 'All')
(3, 'A', 'All'), -- include
(4, 'A', 'All'), -- include
(5, 'A', 'Male'); -- exclude; wrong gender
with PrioritizedData as
(
select
D.*,
[Priority] = row_number() over (partition by D.Category order by case D.Gender when 'All' then 0 else 1 end)
from
#SampleData D
where
D.[Group] = 'A' and
D.Gender in ('Female', 'All')
)
select * from PrioritizedData P where P.[Priority] = 1;

Answer 2

You can use the RANK() window function with results grouped by group and ordered by gender (this works because all is alphabetically before female or male. If your ordering gets more complex than that, you'll have to look at another way to order them.
/* TEST DATA */
; WITH a AS (
SELECT 'A' AS thegroup, 'all' AS gender UNION ALL
SELECT 'A' AS thegroup, 'all' AS gender UNION ALL
SELECT 'A' AS thegroup, 'female' AS gender UNION ALL
SELECT 'B' AS thegroup, 'all' AS gender UNION ALL
SELECT 'C' AS thegroup, 'female' AS gender UNION ALL
SELECT 'C' AS thegroup, 'all' AS gender UNION ALL
SELECT 'D' AS thegroup, 'female' AS gender
)
/* THE QUERY */
SELECT b.*
FROM (
SELECT thegroup, gender, RANK() OVER (PARTITION BY thegroup ORDER BY gender) AS rn /* Sets the ranked groups of 'thegroup' */
FROM a
) b
WHERE b.rn = 1 /* Gets first group. */
AND thegroup = 'A'

Answer 3

data script
declare #data table ([group] char(1), [gender] varchar(16));
insert into #data values ('A', 'all'), ('A', 'female') ,('B', 'all') ,('C', 'female') ,('C', 'all');
query
select
[group] = [d].[group]
,[gender] = [x].[gender]
from
#data as [d]
cross apply
(
select top 1 [gender] from #data where [group] = [d].[group] order by iif([gender] = 'all', 0, 1) asc
) as [x]
group by
[d].[group]
,[x].[gender];