查找列的唯一组合

Question

I'm trying to write a select query but am having trouble, probably because I'm not familiar with SQL Server (usually use MySQL ).

Basically what I need to do is find the number of unique combinations of 2 columns, one a Varchar and one a Double .

There are less rows in one than another, so I've been trying to figure out the right way to do this.

Essentially pretend Table.Varchar has in it:

Table.Varchar
--------------
apple  
orange 

and Table.Float has in it:

Table.Float
--------------
1   
2  
3.  

How could I write a query which returns

QueryResult
-------------
apple1
apple2
apple3
orange1
orange2
orange3

Long day at work and I think I'm just overthinking this what I've tried so far is to concat the two columns and then count but it's not working. Any ideas to better go about this?

Answer 1

Select T1.VarcharField +  CAST(T2.FloatField as Varchar(10)) as [Concat]
from Table.Varchar T1
CROSS JOIN Table.Float T2

this way, you are generating the fields

so, then group by and use Count

select  T.Concat, count(*) from 
(Select T1.VarcharField + CAST(T2.FloatField as Varchar(10)) as [Concat]
    from Table.Varchar T1
    CROSS JOIN Table.Float T2) T
group by T.Concat order by count(*) asc

Answer 2

If they are in the same table:

SELECT a.Field1, b.Field2
FROM [Table] a
    CROSS JOIN [Table] b

or if they are in seperate tables:

SELECT a.Field1, b.Field2
FROM [Table1] a
    CROSS JOIN [Table2] b

Keep in mind that the above queries will match ALL records from the first table with ALL records from the second table, creating a cartesian product .

Answer 3

This will eliminate duplicates:

DECLARE @Varchar TABLE(v VARCHAR(32));

DECLARE @Float TABLE(f FLOAT);

INSERT @Varchar SELECT 'apple' 
  UNION ALL SELECT 'orange' 
  UNION ALL SELECT 'apple';

INSERT @Float SELECT 1 
  UNION ALL SELECT 2 
  UNION ALL SELECT 3;

SELECT v.v + CONVERT(VARCHAR(12), f.f)
 FROM @Varchar AS v
 CROSS JOIN @Float AS f
 GROUP BY v.v, f.f;

Answer 4

A cross join is a join where each record in one table is combined with each record of the other table. Select the distinct values from the table and join them.

select x.Varchar, y.Float
from (select distinct Varchar from theTable) x
cross join (select distinct Float from theTable) y

To find the number of combinations you don't have to actually return all combinations, just count them.

select
  (select count(distinct Varchar) from theTable) *
  (select count(distinct Float) from theTable)

Answer 5

Try This

Possible Cominations.

SELECT 
DISTINCT T1.VarField+CONVERT(VARCHAR(12),T2.FtField) --Get Unique Combinations
FROM Table1 T1 CROSS JOIN Table2 T2 --From all possible combinations
WHERE T1.VarField IS NOT NULL AND T2.FtField IS NOT NULL --Making code NULL Proof

and to just get the Possible Cominations Count

SELECT Count(DISTINCT T1.VarcharField + CONVERT(VARCHAR(12), T2.FloatField))
FROM Table1 T1  
CROSS JOIN Table2 T2 
WHERE T1.VarcharField IS NOT NULL AND T2.FloatField IS NOT NULL