Logical lock in WHERE clause - sql-server

Question

Since FUNCCODE is shared between POSCODE and DEVCODE I can't call out both at the same time to eliminate the null values to insert the data into a separate table called JOINT. POSCODE and DEVCODE are FKs. I know there has to be a much easier way of doing this. I spent the last 2 weeks trying to craft a solution... It feels like I don't understand one thing to make this work. Any advice is appreciated.
Table setup
FUNCCODE | POSCODE | DEVCODE
11 1 NULL
12 NULL 1
13 2 NULL
14 NULL 2
The table needs to be rearranged and then inserted into a separate table called JOINT which is setup as:
POSCODE | POSFUNCCODE |DEVCODE | DEVFUNCCODE
1 11 1 12
2 13 2 14
Some of my attempts XD
Each join creates only 2 of the columns I need
SELECT
dbo.POSITION.POSCODE AS POSCODE,
dbo.FUNC.FUNCCODE AS POSFUNCCODE
FROM FUNC
INNER JOIN POSITION ON dbo.POSITION.POSCODE = dbo.FUNC.POSCODE
UNION ALL
SELECT
dbo.DEVICE.DEVCODE AS DEVCODE,
dbo.FUNC.FUNCCODE AS DEVFUNCCODE
FROM FUNC
INNER JOIN DEVICE ON dbo.DEVICE.DEVCODE = dbo.FUNC.DEVCODE
ORDER BY 1;
Only inserts the last row values
DECLARE #DATE DATETIME = GETDATE()
DECLARE #PC INT;
SELECT #PC = POSCODE
FROM func
WHERE poscode != 0
ORDER BY 1;
DECLARE #FCP INT;
SELECT #FCP = FUNCCODE
FROM FUNC
WHERE POSCODE != 0
ORDER BY 1;
DECLARE #DC INT;
SELECT #DC = devcode
FROM func
WHERE devcode != 0
ORDER BY 1;
DECLARE #FCD INT
SELECT #FCD = FUNCCODE
FROM FUNC
WHERE DEVCODE != 0
ORDER BY 1
INSERT INTO JOINT (POSCODE, POSFUNCCODE, DEVCODE, DEVFUNCCODE, JOINTTIME,
JOINTSTATUS)
VALUES (#PC, #FCP, #DC, #FCD, #DATE, 1)

Answer 1

If my understanding of your problem is correct, I think the below query would be a solution.
INSERT INTO JOINT (POSTCODE, DEVCODE, POSFUNCCODE, DEVFUNCCODE)
SELECT
POSTCODE,
DEVCODE,
MAX(CASE
WHEN POSCODE IS NOT NULL THEN FUNCCODE
ELSE NULL
END) POSFUNCCODE,
MAX(CASE
WHEN DEVCODE IS NOT NULL THEN FUNCCODE
ELSE NULL
END) DEVFUNCCODE
FROM FUNC
GROUP BY POSTCODE,DEVCODE
Second version after a better understanding
INSERT INTO JOINT (POSTCODE, DEVCODE, POSFUNCCODE, DEVFUNCCODE)
SELECT
t1.POSTCODE,
t2.DEVCODE,
t1.POSFUNCCODE,
t2.DEVFUNCCODE
(SELECT
POSTCODE,
MAX(CASE
WHEN POSCODE IS NOT NULL THEN FUNCCODE
ELSE NULL
END) POSFUNCCODE
FROM FUNC
GROUP BY POSTCODE) t1
INNER JOIN
(SELECT
DEVCODE,
MAX(CASE
WHEN DEVCODE IS NOT NULL THEN FUNCCODE
ELSE NULL
END) DEVFUNCCODE
FROM FUNC
GROUP BY DEVCODE) t2
ON t1.POSTCODE = t2.DEVCODE

Answer 2

Against my better judgment, I created a loop which inserted the proper values.... I know this is not the correct way to approach this, please excuse me since my experience in SQL is very little. But this corrects the interface issue in the client program. Shout out to #user4219031 for guidance!
DECLARE #DATE DATETIME = GETDATE()
DECLARE #PC INT = 0;
DECLARE #FCP INT = 12;
DECLARE #DC INT = 0;
DECLARE #FCD INT = 13
WHILE ( #PC < 739 )
BEGIN
INSERT INTO JOINT (POSCODE, POSFUNCCODE, DEVCODE, DEVFUNCCODE, JOINTTIME, JOINTSTATUS)
VALUES( #PC, #FCP, #DC, #FCD, #DATE, 1)
SET #PC = #PC + 1
SET #FCP = #FCP +2
SET #DC = #DC + 1
SET #FCD = #FCD + 2
END

Answer 3

EDIT: I changed my query to account for NULL POSCODE or DEVCODE.
SQL Fiddle
MS SQL Server 2017 Schema Setup:
CREATE TABLE t ( FUNCCODE int, POSCODE int, DEVCODE int ) ;
INSERT INTO t (FUNCCODE, POSCODE, DEVCODE)
VALUES
( 11, 1, NULL )
, ( 12, NULL, 1 )
, ( 13, 2, NULL )
, ( 14, NULL, 2 )
, ( 42, NULL, 1 )
, ( 77, NULL, 7 )
, ( 88, NULL, 8 )
, ( 99, 9, NULL )
;
Create New Table And Insert Records
CREATE TABLE ti ( POSCODE int, pos_FUNCCODE int, DEVCODE int, dev_FUNCCODE int ) ;
INSERT INTO ti ( POSCODE, pos_FUNCCODE, DEVCODE, dev_FUNCCODE)
SELECT t1.POSCODE
, t1.FUNCCODE AS pos_FUNCODE
, t2.DEVCODE
, t2.FUNCCODE AS dev_FUNCCODE
FROM t t1
FULL OUTER JOIN t t2 ON t1.POSCODE = t2.DEVCODE
WHERE t1.POSCODE IS NOT NULL OR t2.DEVCODE IS NOT NULL
;
What's In The New Table?:
SELECT * FROM ti
Results:
| POSCODE | pos_FUNCCODE | DEVCODE | dev_FUNCCODE |
|---------|--------------|---------|--------------|
| 1 | 11 | 1 | 12 |
| 1 | 11 | 1 | 42 |
| 2 | 13 | 2 | 14 |
| 9 | 99 | (null) | (null) |
| (null) | (null) | 7 | 77 |
| (null) | (null) | 8 | 88 |
==========ORIGINAL==========
SQL Fiddle
MS SQL Server 2017 Schema Setup:
CREATE TABLE t ( FUNCCODE int, POSCODE int, DEVCODE int ) ;
INSERT INTO t (FUNCCODE, POSCODE, DEVCODE)
VALUES
( 11, 1, NULL )
, ( 12, NULL, 1 )
, ( 13, 2, NULL )
, ( 14, NULL, 2 )
;
Create New Table And Insert Records
CREATE TABLE ti ( POSCODE int, pos_FUNCCODE int, DEVCODE int, dev_FUNCCODE int ) ;
INSERT INTO ti ( POSCODE, pos_FUNCCODE, DEVCODE, dev_FUNCCODE)
SELECT t1.POSCODE
, t1.FUNCCODE AS pos_FUNCODE
, t2.DEVCODE
, t2.FUNCCODE AS dev_FUNCCODE
FROM t t1
INNER JOIN t t2 ON t1.POSCODE = t2.DEVCODE
WHERE t1.POSCODE IS NOT NULL
;
What's In The New Table?:
SELECT * FROM ti
Results:
| POSCODE | pos_FUNCCODE | DEVCODE | dev_FUNCCODE |
|---------|--------------|---------|--------------|
| 1 | 11 | 1 | 12 |
| 2 | 13 | 2 | 14 |