Append comma delimited string with other data to another table - sql

Question

I am running SQL Server 2008. in a stored procedure, I need to copy TableA to TableB by making a comma-delimted string from a subset of columns in TableA and write it along with some other data to TableB.
TableA contains 12 text columns named 'Column1' thru 'Column12'.
For each row in TableA I need a comma-separated string built from a variable range of columns defined by parameters #startCol and #endCol passed to the stored procedure. I need to copy #startCol and #endCol plus the string to another table.
TableB:
StartCol, EndCol, CommaDelim
This is what I'm trying:
INSERT INTO TableB SELECT #startCol as StartCol, #endCol As EndCol,
COALESCE(???) as CommaDelim
I can't figure out what to pass to the COALESCE function. I'm not even sure I should be using COALESCE. I'm not averse to dynamic SQL
TableA:
Column1 Column2 Column3 ….
'A1' 'A2' 'A3'
'B1' 'B2' 'B3'
.
.
.
what I want in TableB is
StartCol EndCol CommaDelim
1 3 'A1,A2,A3'
1 3 'B1,B2,B3'
one record for each record in TableA
I can't get any result set - I keep getting syntax errors in the COALESCE part

Answer 1

Perhaps a little over-developed, but here is a technique that does NOT require dynamic SQL
Notice I set Columns between 1 & 2, but you can set any range
Example
Declare #YourTable Table ([Column1] varchar(50),[Column2] varchar(50),[Column3] varchar(50))
Insert Into #YourTable Values
('A1','A2','A3')
,('B1','B2','B3')
Declare #Col1 int = 1
Declare #Col2 int = 2
Select StartCol = #Col1
,EndCol = #Col2
,C.*
From #YourTable A
Cross Apply ( values (cast((Select A.* for XML RAW,ELEMENTS XSINIL) as xml))) B(XMLData)
Cross Apply ( values (stuff((Select ',' + Value
From (
Select Seq = row_number() over (order by (select null))
,Item = a.value('local-name(.)','varchar(100)')
,Value = a.value('.','varchar(max)')
From B.XMLData.nodes('/row') as C1(n)
Cross Apply C1.n.nodes('./*') as C2(a)
) B1
Where Seq between #Col1 and #Col2
Order By Seq
For XML Path (''))
,1,1,'')
)
) C(CommaDelim)
Returns
StartCol EndCol CommaDelim
1 2 A1,A2
1 2 B1,B2

Answer 2

You will have to convert them into VARCHAR datatype so that you can concatenate them. COALESCE is picking the first null column in the list.
Example:
ISNULL(CONVERT(VARCHAR(Length),Column1),'')+','+ISNULL(CONVERT(VARCHAR(Length),Column2),'')+','+ISNULL(CONVERT(VARCHAR(Length),Column3),'')
Hope that helps!

Answer 3

I came up with a way so that you do not have to create dynamic sql by creating a function. You may have to modify the select statements to match your schema. You can use the function this way:
select dbo.getString(#startCol, #endCol)
create function getString(#startCol int, #endCol int)
returns varchar(40)
as
begin
declare #str varchar(40) = ""
declare #i int = #startCol
if #endCol < #startCol
begin
return #str
end
while #i < #endCol + 1
begin
if #i = 1
begin
select #str = #str + Column1 + ","
from TableA
end
if #i = 2
begin
select #str = #str + Column2 + ","
from TableA
end
if #i = 3
begin
select #str = #str + Column3 + ","
from TableA
end
if #i = 4
begin
select #str = #str + Column4 + ","
from TableA
end
if #i = 5
begin
select #str = #str + Column5 + ","
from TableA
end
if #i = 6
begin
select #str = #str + Column6 + ","
from TableA
end
if #i = 7
begin
select #str = #str + Column7 + ","
from TableA
end
if #i = 8
begin
select #str = #str + Column8 + ","
from TableA
end
if #i = 9
begin
select #str = #str + Column9 + ","
from TableA
end
if #i = 10
begin
select #str = #str + Column10 + ","
from TableA
end
if #i = 11
begin
select #str = #str + Column11 + ","
from TableA
end
if #i = 12
begin
select #str = #str + Column12 + ","
from TableA
end
set #i = #i + 1
end
set #str = substring(#str, 1, len(#str) - 1)
return #str
end