DB2 SQL 按分隔符拆分记录（如果存在）

Question

I would like to return the portion of a string BEFORE a delimiter (in this case, a hyphen). What I find is that DB2 is throwing an error because there's an inconsistency in the values of the column where some records have a hyphen meanwhile others do not. So, I'd like to return the string before hyphen if it exists, otherwise just return the string as is.

Example shown with COLUMN1 below:

ID	COLUMN1
1	ASHJE-JFE
2	QER-SK
3	KSETK
4	SDJ-EJLF

I wrote the following query to return the string prior/before '-' but, I get the following error:

The statement was not executed because a numeric argument of a scalar function is out of range.

I believe this is because there are records where a hyphen does not exist...

select distinct column1, locate('-',column1), substr(column1,1, (locate('-',column1) - 1)) from db2.table
where column1 is not null
fetch first 25 rows only
with ur

Does anyone know how to accomplish something similar but return the string as is when a hyphen does not exist? Thank you!

Answer 1

You can use a CASE statement to search for the hyphen along with a LIKE operator and % wildcards.

SELECT ID, column1,
CASE WHEN column1 LIKE '%-%'
THEN substr(column1,1,locate('-',column1)-1)
ELSE column1 
END AS column2
FROM fileName
WHERE column1 IS NOT NULL
FETCH FIRST 25 ROWS ONLY

See Fiddle

Result:

ID	COLUMN1	COLUMN2
1	ASHJE-JFE	ASHJE
2	QER-SK	QER
3	KSETK	KSETK
4	SDJ-EJLF	SDJ

Answer 2

You may use the following expression:

SUBSTR (COLUMN1, 1, COALESCE (NULLIF (LOCATE ('-', COLUMN1), 0) - 1, LENGTH (COLUMN1)))