Incorporate case statement in where clause - sql

Question

My requirement is as follows: I need to extract all companies data, which has similar name in table (first 3 words should occur in the name,can be in middle) as the input company name.
My query is working fine for data where name has more than 3 words ,but for less or equal to 3 it's failing.
I didn't get how to incorporate conditions in where clause.
My query is as below
select regno,name from ereg
where
(name like '%' +(
SELECT SUBSTRING(name, 0, CHARINDEX(' ', name, CHARINDEX(' ', name, CHARINDEX(' ', name, 0)+1)+1)) matchingwrd
FROM ereg where regno='C2113-UPD01')+'%')
script is as below
CREATE TABLE ereg(
regnoINT, name VARCHAR(50)
);
INSERT INTO ereg (regno,name)
values
('C2113-UPD01','future company Ltd'),
('C2223-UPD01','MY future company Ltd Corp'),
('C2113-UPD01','Prime Private Furnishings housing Ltd '),
('C26903-UPD01','My Prime Private Furnishings Service '),
for example,its working fine for regno='C2113-UPD01' and gives output -->>'C26903-UPD01','My Prime Private Furnishings Service
but if input is 'C2113-UPD01' My query fails and not able to fetch 'C2223-UPD01' company data

Answer 1

Your table data insert script, the data and the script all seems to be not taken from a working version. I had to clean everything.
What I did to get the 3 words is adding another space in front of the name:
Still your query gave me trouble. But here is how I did that
;With cted as
(
Select regno, name,
SUBSTRING(name + ' ', 0, CHARINDEX(' ', name + ' ', CHARINDEX(' ', name + ' ', CHARINDEX(' ', name + ' ', 0)+1)+1)) as ThreeWords
from ereg
)
Select c1.regno, c1.name, c2.regno, c2.name
from cted c1
inner join cted c2 on c2.name like '%' + c1.ThreeWords + '%' and c1.regno <> c2.regno
Where c1.regno='C2213-UPD01' -- or c1.regno='C2113-UPD01'
Here is the fiddle