Question

I am trying to achieve a list of rows based on a table using SQL and LINQ.
The available table is as followed:

ID  SName  SValue  LName  LValue  FName  FValue
1   TextS  1.1     null   null    null   null
2    null  null    TextL  2.2     null   null
3    null  null    null   null    TextF  3.3

I am trying write a query which can result a list like this:

listColumn1  listColumn2
TextS        1.1
TextL        2.2
TextF        3.3

Please help with your expert advice.
Thank you.

Answer 1

You did not specify what RDBMS you are using but if you are using SQL Server 2008+ and you want to perform this in SQL and then use the result you can UNPIVOT the data:

SELECT x.listColumn1,
  x.listColumn2
FROM YourTable t
CROSS APPLY 
(
    VALUES
        (t.SName, t.SValue),
        (t.LName, t.LValue),
        (t.FName, t.FValue)
) x (listColumn1, listColumn2)
where x.listColumn1 is not null
  and x.listColumn2 is not null

See SQL Fiddle with Demo

Result:

| LISTCOLUMN1 | LISTCOLUMN2 |
-----------------------------
|       TextS |         1.1 |
|       TextL |         2.2 |
|       TextF |         3.3 |