How to write SQL script to update conditional data and constraints? - sql

Question

I have just approached SQL and have not had the solution to do this.
I have 2 tables A and B:
A B
ID (char) Year (char)
Zone (char) Code (char)
ZCode (char)
At first, table B will be completely empty. Ex data of table A:
A
01 A 2013/AA
02 A 2018/KK
03 A null
04 B
05 B 2016/HH
I want to update data from table A to table B provided that only ZCode of Zone has the latest year and ZCode will be separated by a "/". This is the result I want:
B
2018 KK
2016 HH
Looking forward to having someone give me the solution to do this.

Answer 1

A very simple solution if your data is consistent. This only works if your data always have a complete year as number ex:2018on left and only 2 characters on right. This is more of hard coding of column length, cant see a reason why u cant use this.
Using Max will select latest year by code
Insert into tableB (Year,Code)
select Max(Left(Columnname,4)) year,
Right (columnname,2) Code from TableA
where Right (columnname,2) is not null or Right (columnname,2)<> ''
group by Right (columnname,2)

Answer 2

Try This
IF OBJECT_ID('dbo.TableA')IS NOT NULL
DROP TABLE TableA
IF OBJECT_ID('dbo.TableB')IS NOT NULL
DROP TABLE TableB
CREATE TABLE TableA (Id INT,Zone VARCHAR(2) ,ZCode VARCHAR(20))
CREATE TABLE TableB ([Year] INT,Code VARCHAR(20))
GO
INSERT INTO TableA(Id,Zone,ZCode)
SELECT 01,'A','2013/AA' UNION ALL
SELECT 02,'B','2016/HH' UNION ALL
SELECT 03,'A','2018/KK'
GO
INSERT INTO TableB
SELECT [Year]
,[Code]
FROM
(
SELECT SUBSTRING(ZCode,0,CHARINDEX('/',ZCode)) As [Year]
,SUBSTRING(ZCode,CHARINDEX('/',ZCode)+1,LEN(ZCode)) AS Code
FROM TableA
)dt
SELECT * FROM TableB ORDER BY [Year] DESC
Result
Year Code
------------
2018 KK
2016 HH
2013 AA

Answer 3

In order to UPDATE in tableB you would required to JOIN the table with tableB on Year / Code columns
WITH CTE AS
(
SELECT
left(a.zcode, 4) year,
substring(a.zcode, charindex('/', a.zcode)+1, len(a.zcode)) code
FROM tableA a
INNER JOIN (
select Zone, max(left(zcode, 4)) year
FROM tableA
GROUP BY Zone
)b ON a.Zone = b.zone and b.year = left(a.zcode, 4)
)
SELECT * FROM CTE

Answer 4

Below code snippet would give your desired output, now based on your requirement you can either do an INSERT into tableB or do an UPDATE
DECLARE #A TABLE(ID CHAR(10), ZONE CHAR(10), ZCODE CHAR(20))
INSERT INTO #A VALUES
('01', 'A', '2013/AA'),
('02', 'B', '2016/HH'),
('03', 'A', '2018/KK')
SELECT Year,Code FROM(
SELECT Year,Code,ROW_NUMBER() OVER (PARTITION BY ZONE ORDER BY Year DESC) rn FROM
(SELECT cast(concat('<x>', REPLACE(ZCODE, '/', '</x><x>'), '</x>') as xml).value('/x[1]','varchar(100)') AS Year,
cast(concat('<x>', REPLACE(ZCODE, '/', '</x><x>'), '</x>') as xml).value('/x[2]','varchar(100)') AS Code,*
FROM #A WHERE ZCODE IS NOT NULL) t1) t2
WHERE rn = 1;

Answer 5

You can use this query to insert data into table B, when it is completely empty
INSERT INTO B ([YEAR], [MONTH])
select
Substring(ZCode,0,charindex('/',ZCode)) BYEAR,
Substring(ZCode,charindex('/',ZCode)+1,LEN(ZCode)-charindex('/',ZCode)) BCode
from A
else use can update this query to update record of table B based on BCode.
Query edited for NOT NULL and GROUP condition
select MAX(v.BYEAR), v.BCode from
(select
Substring(ZCode,0,charindex('/',ZCode)) BYEAR
,Substring(ZCode,charindex('/',ZCode)+1,LEN(ZCode)-charindex('/',ZCode)) BCode
from B ) v
Where v.BCODE IS NOT NULL
Group by v.BCODE