How to find second value inside a column - sql

Question

How do I list the names of all band members with the same last name?
The column has values like this
band_NAME
-------------------
Carla Thomas
Stephen E. Rice
Cynthia P. Tree
Richard Anthony Paul
Ann Frances Smith
Lorace Black
Timothy Adam Paul
I know we would have to use instr and substr. I just don't get how we would determine the position.
I know the basic format is going to be like
SELECT band_NAME
FROM TABLE
where substr(band_name, ?, instr( ) IN
(select substr(band_name, ?, instr( )-1)
from table
group by SUBSTR(band_NAME , ?, INSTR( )-1 )
HAVING COUNT(* ) > 1 );
But what goes in the question marks and inside the instr?
Would appreciate any help on this!

Answer 1

I'm assuming that your delimiter between first and last name is a single space. More spaces in the string are a part of last name. Thus, you probably want to search for the first space character.
Return position of the first occurence of substring with instr(str, substr).
Then, use substring(str, pos) to return the substring starting at a given position (feed by instr function).
SELECT substring(band_name, instr(band_name, ' '))
FROM yourtable

Answer 2

Try this:
SELECT t1.band_NAME
FROM TABLE t1 LEFT JOIN TABLE t2
ON SUBSTRING_INDEX(t1.band_name, ' ', - 1) = SUBSTRING_INDEX(t2.band_name, ' ', - 1)
WHERE t1.band_name <> t2.band_name
And this like your pseudocode MySQL:
SELECT band_NAME FROM TABLE
Where FIND_IN_SET (SUBSTRING_INDEX(band_name, ' ', -1),
(Select SUBSTRING_INDEX(band_name, ' ', -1) bn
From TABLE Group by bn
having Count(bn) > 1
)
)
SQL Server
SELECT band_NAME FROM TABLE
Where
SUBSTRING(band_NAME, CHARINDEX(' ', band_NAME) + 1, LEN(band_NAME)) AS [Last Name]
IN
(Select SUBSTRING(band_NAME, CHARINDEX(' ', band_NAME) + 1, LEN(band_NAME)) AS [Last Name]
From TABLE Group by [Last Name] -- or SUBSTRING(band_NAME, CHARINDEX(' ', band_NAME) + 1, LEN(band_NAME)) AS [Last Name]
having Count(*) > 1
)
)
Additionally I thinks you can benefit from STRING_SPLIT in some way

Answer 3

Try This
with cte as
(
select band_name, ROW_NUMBER() over(partition by SUBSTRING(band_name,CHARINDEX(' ',band_name),LEN(band_name)) order by band_name) as cnt,
SUBSTRING(band_name,CHARINDEX(' ',band_name),LEN(band_name)) as lastname
from your_table
)
select band_name
from cte
where lastname in (select lastname from cte where cnt > 1)

Answer 4

okay,
The best solution is to change your schema and store last name in a separate column.
In the mean time you could get the last name like this,
SELECT
[band_NAME],
CASE WHEN CHARINDEX(' ', [band_NAME]) > 0
THEN
RIGHT([band_NAME], CHARINDEX(' ', REVERSE([band_NAME])))
ELSE
[band_NAME]
END [LastName]
FROM
[TABLE]
You could then group them like this
SELECT
[LastName],
COUNT(*)
FROM
(
SELECT
[band_NAME],
CASE WHEN CHARINDEX(' ', [band_NAME]) > 0
THEN
RIGHT([band_NAME], CHARINDEX(' ', REVERSE([band_NAME])))
ELSE
[band_NAME]
END [LastName]
FROM
[TABLE]
) [TABLEWithLastName]
GROUP BY
[LastName];