How to transform records data into columns - sql

Question

Please find the sample data:
h_company_id company_nm mainphone1 phone_cnt
20816 800 Flowers 5162377000 3
20816 800 Flowers 5162377131 1
20820 1st Source Corp. 5742353000 3
20821 1st United Bancorp 5613633400 2
20824 3D Systems Inc. 8033273900 4
20824 3D Systems Inc. 8033464010 1
11043 3I Group PLC 2079757115 1
11043 3I Group PLC 2079753731 15
Desired Output:
h_company_id company_nm mainphone1 phone_cnt mainphone2 phone_cnt2
20816 800 Flowers 5162377000 3 5162377131 1
20820 1st Source Corp. 5742353000 3 NULL NULL
20821 1st United Bancorp 5613633400 2 NULL NULL
20824 3D Systems Inc. 8033273900 4 8033464010 1
11043 3I Group PLC 2079757115 1 2079753731 15
(copy above in notepad/excel)
Hi Guys,
I want to transpose records of columns mainphone1 and phone_cnt as new columns namely mainphone2, phone_cnt2 so that the data in column h_company_id should be unique means there should be only single entry of h_company_id.
Thanks in advance!

Answer 1

Transforming from rows into columns is called a PIVOT and there are several different ways that this can be done in SQL Server.
Aggregate / CASE: You can use an aggregate function along with a CASE expression. This will work by applying the row_number() windowing function to the data in your table:
select h_company_id, company_nm,
max(case when seq = 1 then mainphone1 end) mainphone1,
max(case when seq = 1 then phone_cnt end) phone_cnt1,
max(case when seq = 2 then mainphone1 end) mainphone2,
max(case when seq = 2 then phone_cnt end) phone_cnt2
from
(
select h_company_id, company_nm, mainphone1, phone_cnt,
row_number() over(partition by h_company_id order by mainphone1) seq
from yourtable
) d
group by h_company_id, company_nm;
See SQL Fiddle with Demo. The CASE expression checks if the sequence number has the value 1 or 2 and then places the data in the column.
UNPIVOT / PIVOT: Since you want to PIVOT data that exists in two columns, then you will want to UNPIVOT the mainphone1 and phone_cnt columns first to get them in the same column, then apply the PIVOT function.
The UNPIVOT code will be similar to the following:
select h_company_id, company_nm,
col+cast(seq as varchar(10)) col,
value
from
(
select h_company_id, company_nm,
cast(mainphone1 as varchar(15)) mainphone,
cast(phone_cnt as varchar(15)) phone_cnt,
row_number() over(partition by h_company_id order by mainphone1) seq
from yourtable
) d
unpivot
(
value
for col in (mainphone, phone_cnt)
) unpiv;
See Demo. This query gets the data in the following format:
| H_COMPANY_ID | COMPANY_NM | COL | VALUE |
---------------------------------------------------------------
| 11043 | 3I Group PLC | mainphone1 | 2079753731 |
| 11043 | 3I Group PLC | phone_cnt1 | 15 |
| 11043 | 3I Group PLC | mainphone2 | 2079757115 |
| 11043 | 3I Group PLC | phone_cnt2 | 1 |
| 20816 | 800 Flowers | mainphone1 | 5162377000 |
Then you apply the PIVOT function to the values in col:
select h_company_id, company_nm,
mainphone1, phone_cnt1, mainphone2, phone_cnt2
from
(
select h_company_id, company_nm,
col+cast(seq as varchar(10)) col,
value
from
(
select h_company_id, company_nm,
cast(mainphone1 as varchar(15)) mainphone,
cast(phone_cnt as varchar(15)) phone_cnt,
row_number() over(partition by h_company_id order by mainphone1) seq
from yourtable
) d
unpivot
(
value
for col in (mainphone, phone_cnt)
) unpiv
) src
pivot
(
max(value)
for col in (mainphone1, phone_cnt1, mainphone2, phone_cnt2)
) piv;
See SQL Fiddle with Demo.
Multiple Joins: You can also join on your table multiple times to get the result.
;with cte as
(
select h_company_id, company_nm, mainphone1, phone_cnt,
row_number() over(partition by h_company_id order by mainphone1) seq
from yourtable
)
select c1.h_company_id,
c1.company_nm,
c1.mainphone1,
c1.phone_cnt phone_cnt1,
c2.mainphone1 mainphone2,
c2.phone_cnt phone_cnt2
from cte c1
left join cte c2
on c1.h_company_id = c2.h_company_id
and c2.seq = 2
where c1.seq = 1;
See SQL Fiddle with Demo.
Dynamic SQL: Finally if you have an unknown number of values that you want to transform, then you will need to implement dynamic SQL to get the result:
DECLARE #cols AS NVARCHAR(MAX),
#query AS NVARCHAR(MAX)
select #cols = STUFF((SELECT ',' + QUOTENAME(col+cast(seq as varchar(10)))
from
(
select row_number() over(partition by h_company_id order by mainphone1) seq
from yourtable
) d
cross apply
(
select 'mainphone', 1 union all
select 'phone_cnt', 2
) c (col, so)
group by seq, so, col
order by seq, so
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)')
,1,1,'')
set #query = 'SELECT h_company_id, company_nm,' + #cols + '
from
(
select h_company_id, company_nm,
col+cast(seq as varchar(10)) col,
value
from
(
select h_company_id, company_nm,
cast(mainphone1 as varchar(15)) mainphone,
cast(phone_cnt as varchar(15)) phone_cnt,
row_number() over(partition by h_company_id order by mainphone1) seq
from yourtable
) d
unpivot
(
value
for col in (mainphone, phone_cnt)
) unpiv
) x
pivot
(
max(value)
for col in (' + #cols + ')
) p '
execute(#query)
See SQL Fiddle with Demo. All give a result:
| H_COMPANY_ID | COMPANY_NM | MAINPHONE1 | PHONE_CNT1 | MAINPHONE2 | PHONE_CNT2 |
-----------------------------------------------------------------------------------------
| 20820 | 1st Source Corp. | 5742353000 | 3 | (null) | (null) |
| 20821 | 1st United Bancorp | 5613633400 | 2 | (null) | (null) |
| 20824 | 3D Systems Inc. | 8033273900 | 4 | 8033464010 | 1 |
| 11043 | 3I Group PLC | 2079753731 | 15 | 2079757115 | 1 |
| 20816 | 800 Flowers | 5162377000 | 3 | 5162377131 | 1 |

Answer 2

The following could work (assuming your table is called company):
SELECT
c1.h_company_id,
c1.company_nm,
c1.mainphone1,
c1.phone_cnt,
c2.mainphone1 AS mainphone2,
c2.phone_cnt AS phone_cnt2
FROM
company AS c1
LEFT JOIN
company AS c2 ON c2.h_company_id = c1.h_company_id
However, to respect good practice, wouldn't it be better to separate your data in two tables?
the company table, with 2 columns: h_company_id(PK) and company_nm
the phone table, with 4 columns: phone_id (PK), h_company_id (FK), mainphone and phone_cnt
It would allow you to have as many phone numbers per company as you want (including none).

Answer 3

Try this query. This will help you
SELECT t.H_COMPANY_ID,t.COMPANY_NM, a.mainphone1,a.PHONE_CNT,b.mainphone1 mainphone2,b.PHONE_CNT PHONE_CNT2 FROM table_name t
INNER JOIN
(
SELECT h_company_id,phone_cnt,mainphone1 FROM table_name
WHERE mainphone1
IN(
SELECT max(mainphone1) mainphone1 FROM table_name GROUP BY h_company_id
)
)a ON t.H_COMPANY_ID = a.h_company_id
INNER JOIN
(
SELECT h_company_id,phone_cnt,mainphone1 FROM table_name
WHERE mainphone1
IN(
SELECT min(mainphone1) mainphone1 from table_name GROUP BY h_company_id
)
)b ON t.H_COMPANY_ID = b.H_COMPANY_ID
GROUP BY t.H_COMPANY_ID,a.mainphone1,t.COMPANY_NM,a.PHONE_CNT,b.mainphone1,b.PHONE_CNT