Transact-SQL] [number of occurrences of the whole table of all the values

Original: [] Transact-SQL whole number of occurrences of all the values in the table

A table with 3, 5 rows, a total of 15 values, now want to calculate the number of the entire table all values ​​appear in the table, but the number of columns in the table here is uncertain, the above example is 3, the actual on there may be 5, 20, so the steps to solve the problem is this:

1, you must know how many columns, then construct a dynamic statement, to merge into one in these columns.

2, and then to re-calculate all possible values.

3, the final calculation of how many times each value appears in the table.

 

   
   
if(OBJECT_ID('dbo.wc') is not null)
drop table dbo.wc
go


create table wc
(
a nvarchar( 100),
b nvarchar( 100),
c nvarchar( 100)
)

insert into wc
values( '1', '2', '3'),
( 'a', 'f', 'd'),
( '2', 'b', 'c'),
( null, 'c', 'w'),
( '3', 'd', null)


declare @temp table (cn nvarchar( 100));

declare @i int = 1;

declare @v varchar( max)= '';

declare @ column varchar( 100)= '';

while @i <= (
select count(*)
from sys.tables t
inner join sys.columns c
on t.object_id =c.object_id
where t.name = 'wc'
)
begin
select @ column = c.name
from sys.tables t
inner join sys.columns c
on t.object_id =c.object_id
where t.name = 'wc'
and c.column_id = @i

set @i = @i + 1

set @v = @v + ' select '+ @ column + ' from wc union all'

end

select @v = LEFT(@v, len(@v)- LEN( 'union all'))
--select @v

insert into @temp
exec (@v)

;with a
as
(
select cn
from @temp
where cn is not null
group by cn
)

select a.cn,
COUNT(t.cn)
from a
inner join @temp t
on a.cn = t.cn
group by a.cn