Postgresql put strings inside quotes with array_to_string

Question

In select I have used array_to_string like this (example)

array_to_string(array_agg(tag_name),';') tag_names

I got resulting string "tag1;tag2;tag3;..." but I would like to get resulting string as "'tag1';'tag2';'tag3';...".

How can I do this in Postgres?

Answer 1

Use the functions string_agg() and format() with the %L placeholder, which quotes the argument value as an SQL literal.

with my_table(tag_name) as (
values 
    ('tag1'),
    ('tag2'),
    ('tag3')
)

select string_agg(format('%L', tag_name), ';' order by tag_name) tag_names
from my_table;

      tag_names       
----------------------
 'tag1';'tag2';'tag3'
(1 row)

Alternatively, format('%L', tag_name) may be replaced with quote_nullable(tag_name).

Answer 2

Or your can use unnest, format, array_agg and array_to_string in one request like this :

select array_to_string(t.tag, ',')  
from (  
    select array_agg(format('%L', t.tag)) as tag  
    from (  
        select unnest(tag_name) as tag  
    ) t  
) t;

Answer 3

Or use

array_to_string(array_agg(''''||tag_name||''''),';') tag_names 

or even simpler (thanks for the commenting :) )

string_agg(''''||tag_name||''''),';') tag_names 

Note:

When dealing with multiple-argument aggregate functions, note that the ORDER BY clause goes after all the aggregate arguments. For example, write this:

SELECT string_agg(a, ',' ORDER BY a) FROM table;

not this:

SELECT string_agg(a ORDER BY a, ',') FROM table; -- incorrect

See https://www.postgresql.org/docs/current/static/sql-expressions.html#SYNTAX-AGGREGATES

Answer 4

You can use string_agg() function with '''; ''' so it will be like

SELECT string_agg(tag_name, '''; ''') from my_table