```
[PlayerCode] | [Name]   | [Age] | [Club]
142          | Messi    | 34    | PSG
333          | Ronaldo  | 36    | Manchester United
532          | Pique    | 34    | FC Barcelona

[PlayerCode] | [Key]    | [Value]
142          | Name     | Messi
142          | Age      | 34 
142          | Club     | PSG
333          | Name     | Ronaldo
333          | Age      | 36
333          | Club     | Manchester United
532          | Name     | Pique
532          | Age      | 34
532          | Club     | FC Barcelona

```

I want to convert the first table to the second key/value table by using SQL Server.
I assume that the 'unpivot' function will be used to do the conversion, but I don't know how..

Does anyone know how to do this?