Dynamically generate columns for crosstab in PostgreSQL

Question

I am trying to create crosstab queries in PostgreSQL such that it automatically generates the crosstab columns instead of hardcoding it. I have wri

Answer 1

I realise this is an older post but struggled for a little while on the same issue.

My Problem Statement: I had a table with muliple values in a field and wanted to create a crosstab query with 40+ column headings per row.

My Solution was to create a function which looped through the table column to grab values that I wanted to use as column headings within the crosstab query.

Within this function I could then Create the crosstab query. In my use case I added this crosstab result into a separate table.

E.g.

CREATE OR REPLACE FUNCTION field_values_ct ()
 RETURNS VOID AS $$
DECLARE rec RECORD;
DECLARE str text;
BEGIN
str := '"Issue ID" text,';
   -- looping to get column heading string
   FOR rec IN SELECT DISTINCT field_name
        FROM issue_fields
        ORDER BY field_name
    LOOP
    str :=  str || '"' || rec.field_name || '" text' ||',';
    END LOOP;
    str:= substring(str, 0, length(str));

    EXECUTE 'CREATE EXTENSION IF NOT EXISTS tablefunc;
    DROP TABLE IF EXISTS temp_issue_fields;
    CREATE TABLE temp_issue_fields AS
    SELECT *
    FROM crosstab(''select issue_id, field_name, field_value from issue_fields order by 1'',
                 ''SELECT DISTINCT field_name FROM issue_fields ORDER BY 1'')
         AS final_result ('|| str ||')';
END;
$$ LANGUAGE plpgsql;