MySQL 8.0

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create table mytable as 
select 'name1,name2' column1 
union all select 'name2,name3'
union all select 'name4,name1,name3'

Records: 3  Duplicates: 0  Warnings: 0


select * from mytable


column1


name1,name2

name2,name3

name4,name1,name3


with recursive 
    data as (select concat(column1, ',') rest from mytable),
    words as (
        select substring(rest, 1, locate(',', rest) - 1) word, substring(rest, locate(',', rest) + 1) rest
        from data
        union all
        select substring(rest, 1, locate(',', rest) - 1) word, substring(rest, locate(',', rest) + 1) rest
        from words
        where locate(',', rest) > 0
)
select distinct word from words order by word


word


name1

name2

name3

name4