IF THEN Statement in SQL to OpenEdge - sql

Question

I'm struggeling with an if statement towards an OpenEdge database via ODBC. The query I have works like a charm, but Progress wants me to define the if statement different and I have no clue. Is there anyone who can define the correct query for me?
IF
{Crediteur code|type=string} = 'HOEFASTE'
BEGIN
(SELECT
inok."vest-kd-arvo"+RTRIM('-') + RIGHT(CAST((inok."inok-nr" + 1000000) AS varchar(7)),6) AS inokvalue
,RTRIM("leso-kd")+RTRIM('-')+inok."vest-kd-arvo"+RTRIM('-')+CAST("inok-nr"AS varchar(6)) AS inokdisplay
,RIGHT(CAST((inok."inok-nr") AS varchar(7)),6) + '-' + inok."vest-kd-arvo" + '-' + RTRIM("leso-kd") AS inoknr
,RTRIM("leso-kd") AS soortfact
FROM
PUB.inok
WHERE
inok."vcdc-nr" = {Administratie|type=int32}
AND inok."inss-kd" NOT IN ('H','G')
)
ELSE
(SELECT
inok."vest-kd-arvo"+RTRIM('-') + RIGHT(CAST((inok."inok-nr" + 1000000) AS varchar(7)),6) AS inokvalue
,RTRIM("leso-kd")+RTRIM('-')+inok."vest-kd-arvo"+RTRIM('-')+CAST("inok-nr"AS varchar(6)) AS inokdisplay
,RIGHT(CAST((inok."inok-nr") AS varchar(7)),6) + '-' + inok."vest-kd-arvo" + '-' + RTRIM("leso-kd") AS inoknr
,RTRIM("leso-kd") AS soortfact
FROM
PUB.inok
WHERE
inok."rela-kd-kre" = {Crediteur code|type=string}
AND inok."vcdc-nr" = {Administratie|type=int32}
AND inok."inss-kd" NOT IN ('H','G')
)
END

Answer 1

If I understand correctly, only your WHERE-clause is different, based on "Crediteur code".
You could move the IF inside of the WHERE-clause. That will leave you with a single SELECT-statement. Does this alternative work for you?
SELECT
inok."vest-kd-arvo"+RTRIM('-') + RIGHT(CAST((inok."inok-nr" + 1000000) AS varchar(7)),6) AS inokvalue
,RTRIM("leso-kd")+RTRIM('-')+inok."vest-kd-arvo"+RTRIM('-')+CAST("inok-nr"AS varchar(6)) AS inokdisplay
,RIGHT(CAST((inok."inok-nr") AS varchar(7)),6) + '-' + inok."vest-kd-arvo" + '-' + RTRIM("leso-kd") AS inoknr
,RTRIM("leso-kd") AS soortfact
FROM
PUB.inok
WHERE
inok."rela-kd-kre" = (CASE WHEN {Crediteur code|type=string} = 'HOEFASTE' THEN inok."rela-kd-kre" ELSE {Crediteur code|type=string} END)
AND inok."vcdc-nr" = {Administratie|type=int32}
AND inok."inss-kd" NOT IN ('H','G')