How to get the first letter of each word in SQL - sql

Question

I tried to run this query to get the initial letter of each word, and it worked for strings of 4 words, yet if the string has only two words, it duplicates the second word's initial.
select
substring(column_name, 1, 1) +
case
when 0 <> charindex(' ', column_name) + 1
then substring(column_name, charindex(' ',column_name) + 1, 1)
else ''
end +
case
when 0 <> charindex(' ', column_name, charindex(' ', column_name) + 1)
then substring(column_name, charindex(' ', column_name, charindex(' ', column_name) + 1) + 1, 1)
else ''
end +
case
when 0 <> charindex(' ', column_name, charindex(' ', column_name, charindex(' ', column_name) + 1) + 1)
then substring(column_name, charindex(' ', column_name, charindex(' ', column_name, charindex(' ', column_name) + 1) + 1) + 1, 1)
else ''
end
from table_name

Answer 1

You didn't specify which RDBMS you are using. This should work in SQL Server:
drop table if exists table_name
create table table_name (
column_name varchar(255)
)
insert table_name
values ('See Jane')
, ('See Jane run')
, ('See Jane run and jump over the lazy dog.')
select stuff((SELECT '' + t2.fc
from (
select left(str.value, 1) fc
, charindex(' ' + str.value + ' ', ' ' + t.column_name + ' ') idx
from string_split(t.column_name, ' ') str
) t2
order by t2.idx
FOR XML PATH('')
), 1, 0, '') as FirstChars
from table_name t
The idx column is used to order the ouptut because string_split does not promise to return the results in any particular order. Thanks to Aaron Bertrand - https://dba.stackexchange.com/questions/207274/string-split-and-ordered-results

Answer 2

Given the use of charindex in your question, I'm assuming you are using SQL Server. The CTE generates a tall view of your data using string_split function, with each letter on it's own row. We then select from it and group by id, and apply the string_agg function to place back into a single row.
Password guessing?
create table my_data (
id integer,
comments varchar(50)
);
insert into my_data (id, comments) values
(1, 'Thank goodness its friday'),
(2, 'I want 2 scoops of ice cream');
select * from my_data;
id
comments
1
Thank goodness its friday
2
I want 2 scoops of ice cream
with cte (id, first_char) as (
select id, substring(ss.value, 1, 1) as first_char
from my_data
cross apply string_split(comments, ' ')ss
)
select t.id,
string_agg(t.first_char, ',') as letters_delimited,
string_agg(t.first_char, '') as letters_not_delimited
from cte t
group by t.id
id
letters_delimited
letters_not_delimited
1
T,g,i,f
Tgif
2
I,w,2,s,o,i,c
Iw2soic
fiddle here

Answer 3

You can extend your approach with recursion
WITH cte_name AS (
select CONVERT(nvarchar(max), substring(column_name, 1, 1)) conc,
column_name n,
charindex(' ', column_name, 0) pos
from table_name
UNION ALL
select conc + substring(n, pos + 1, 1) as conc,
n,
charindex(' ', n, pos + 1) pos
from cte_name where pos > 0
)
SELECT *
FROM cte_name
where pos = 0;