Question : Need Help With a Complex Query in TSQL

Hi Experts I need a help regarding a query I am developing, Let me explain the process first.
I have an Excel File with Data and it is being loaded into a Table(File_Master) in SQl server.

The header of the Excel File is Like:
FileNo, Name, Address, Company, Phone, Email, Var1, Var2, Var3, Var4, Var5, Var6, Var7, Var8, Var9, Var10

Structure Of My Table (File_Master):
ID, FileNo, Name, Address, Company, Phone, Email, Var1, Var2, Var3, Var4, Var5, Var6, Var7, Var8, Var9, Var10

Values That go into table are Like

1, 101, aa, 12 St, Comp1, 657646984, [email protected], bcd, gfh, hgf,jhg
2, 101, zdvf, 13 St, Comp2, 657646984, [email protected], bcd, gfh, hgf,jhg
3, 101, er, 112 St, Comp3, 657646984, [email protected], bcd, gfh, hgf,jhg
4, 102, fef, 156 St, Comp11, 657646984, [email protected], bcd, gfh, hgf,jhg,gfh, hgf,jhg
5, 102, sdf, 165 St, Comp13, 657646984, [email protected], bcd, gfh, hgf,jhg,gfh, hgf,jhg
6, 103, hgj, 1656 St, Comp34, 657646984, [email protected]
7, 103, er, 15645 St, Compa, 657646984, [email protected]
8, 104, zd, 145 St, Comp23, 657646984, [email protected], bcd
9, 105, rt, 154 St, Compe2, 657646984, [email protected], bcd, gfh
10, 105, rer, 156 St, Comp456, 657646984, [email protected], bcd, gfh
11, 101, fd, 154 St, Comp65, 657646984, [email protected], bcd, gfh, hgf
12, 101, tw, 154 St, Comp34, 657646984, [email protected], bcd, gfh, hgf

I do have one more table (File_Column_Master) Like this:

ID, FileNo,FileDesc, ColumnName, OriginalColumnName

Values That go into table are Like

1, 101, File1, Var1, OGCol1
2, 101, File1, Var2, OGCol2
3, 101, File1, Var3, OGCol3
4, 101, File1, Var4, OGCol4
5, 102, File2, Var1, File2Col1
6, 102, File2, Var2, File2Col2
7, 102, File2, Var3, File2Col3
8, 102, File2, Var4, File2Col4
9, 102, File2, Var5, File2Col5
10, 102, File2, Var6, File2Col6
11, 102, File2, Var7, File2Col7
12, 104, File4, Var1, MyOrigCol1
13, 105, File5, Var1, CCOL1
14, 105, File5, Var2, CCol2

The Column Names in the File_master Table Var1, Var2, Var3, Var4, Var5, Var6, Var7, Var8, Var9, Var10 have their original column names in the File_Column_Master table.

My requirement is like I need to develop a generic query by joining these 2 tables to select data from a specific file with the original column names in the header.

Suppose If I have to select Only Data For FileNo:101 My Header should look like this

ID, FileNo, Name, Address, Company, Phone, Email,OGCOL1, OGCOL2, OGCOL3, OGCOL4

And If I have to select Data for FileNo 102 My Header should look like this

ID, FileNo, Name, Address, Company, Phone, Email,File2Col1,File2Col2, File2Col3,File2Col4,File2Col5,File2Col6,File2Col7

So My Requirement is like I need to Develop a generic query and the user changes the File No in the Where Clause when ever they want.

Is there a way that this query can be written, Or is it possible. For me I really don't have a clue about how to develop a query like this.

Your suggestions will help me greatly, Any Help would be highly Appreciated...

Thanks In Advance.....

Answer : Need Help With a Complex Query in TSQL

I think you need dynamic SQL there. So maybe something like this

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declare @strSQL varchar(max) 
declare @cols varchar(max)
declare @FileNo int

set @fileNo = 101

set @cols = stuff((select  ',' + OriginalColumnName from File_Column_Master where Fileno = @FileNo for xml path('')), 1, 1, '')

set @strSQL = 'select ID, FileNo, Name, Address, Company, Phone, Email, ' + @cols + ' from yourtable where id = ' + cast(@FileNo as varchar)

exec(@strSQL)