Generate three rows in select query - sql

Question

I have following table
SELECT TableCode, Col1, Col2
FROM TableA
WHERE TableCode = 23
Result of Table:
TableCode | Col1 | Col1
23 | CustCode | QS
23 | CatCode | QS
After that i wrote one query on TableA which return following output
Query :
SELECT TableCode,x.ColCode,
x.ColumnName + '_' + CONVERT(VARCHAR(5), ROW_NUMBER() OVER (PARTITION BY X.COL ORDER BY X.COL)) [ColumnName],X.Values,
ROW_NUMBER() OVER (PARTITION BY X.COL ORDER BY X.COL) [RowNo]
FROM TableA a CROSS APPLY
(SELECT 1 ColCode,'ParaName' ColumnName,Col1 Values
UNION ALL
SELECT 2,'ParaSource',Col2
) x
WHERE TableCode = 23;
Result :
TableCode | ColCode | ColumnName | Values | RowNo
23 | 1 | ParaName_1 | CustCode | 1
23 | 1 | ParaName_2 | CatCode | 2
23 | 2 | ParaSource_1 | QS | 1
23 | 2 | ParaSource_2 | QS | 2
And i required following output:
Required Output :
TableCode | ColCode | ColumnName | Values | RowNo
23 | 1 | ParaName_1 | CustCode | 1
23 | 1 | ParaName_2 | CatCode | 2
23 | 1 | ParaName_3 | Null | 3
23 | 2 | ParaSource_1 | QS | 1
23 | 2 | ParaSource_2 | QS | 2
23 | 2 | ParaSource_3 | null | 3

Answer 1

Using a couple of common table expressions and row_number() along with the table value constructor (values (...),(...))
to cross join numbers 1, 2, and 3 then using a left join to return 3 rows per TableCode even when you do not have three rows in the source table.
;with numbered as (
select *, rn = row_number() over (order by (select 1))
from TableA
where TableCode = 23
)
, cte as (
select distinct tc.TableCode, a.Col1, a.Col2, v.rn
from numbered tc
cross join (values (1),(2),(3)) v (rn)
left join numbered a
on a.TableCode = tc.TableCode
and a.rn = v.rn
)
select
a.TableCode
, x.ColCode
, [ColumnName] = x.ColumnName + '_' + convert(varchar(5),a.rn)
, X.Value
,[RowNo] = a.rn
from cte a
cross apply (values (1,'ParaName',Col1),(2,'ParaSource',Col2))
as x(ColCode, ColumnName, Value)
order by ColCode, RowNo;
rextester demo: http://rextester.com/CJU8986
returns:
+-----------+---------+--------------+----------+-------+
| TableCode | ColCode | ColumnName | Value | RowNo |
+-----------+---------+--------------+----------+-------+
| 23 | 1 | ParaName_1 | CustCode | 1 |
| 23 | 1 | ParaName_2 | CatCode | 2 |
| 23 | 1 | ParaName_3 | NULL | 3 |
| 23 | 2 | ParaSource_1 | QS | 1 |
| 23 | 2 | ParaSource_2 | QS | 2 |
| 23 | 2 | ParaSource_3 | NULL | 3 |
+-----------+---------+--------------+----------+-------+

Answer 2

This would appear to do what you want:
SELECT TableCode, x.ColCode, v.*
FROM TableA a CROSS APPLY
(VALUES (1, 'ParaName-1', Col1, 1),
(2, 'ParaName-2', Col2, 2),
(3, 'ParaName-3', NULL, 2)
) v(ColCode, ColumnName, [Values], RowNo)
WHERE TableCode = 23;
I see no reason to use row_number() when you can just read in the correct values. Also, VALUES is a SQL keyword so it is a really bad column name.