Question

Can anyone help me with this? I have a task to write a function, which would generate HTML tables from given table name in PostgreSQL(plpgsql language).
I have written this, but it’s far from what I need. It would generate a table for columns I would give (at the moment just one), but I need to just give the table a name.

CREATE OR REPLACE FUNCTION genhtml2(tablename text, columnname text)
RETURNS text AS
$BODY$
DECLARE
result text := ”;
searchsql text := ”;
var_match text := ”; BEGIN
searchsql := ‘SELECT ‘ || columnname || ‘
FROM ‘ || tablename || ”;

result := '<table>';
FOR var_match IN EXECUTE(searchsql) LOOP
    IF result > '' THEN
        result := result || '<tr>' || var_match || '</tr>';
    END IF;
END LOOP;
result :=  result || '</table>';

RETURN result; END; $BODY$ LANGUAGE ‘plpgsql’ IMMUTABLE;

Answer 1

You could search the calalogs for the columns in the table first, then use them to generate the query and to set the table header.

colsql := $QUERY$SELECT attname
                 FROM pg_attribute AS a JOIN pg_class AS c ON a.attrelid = c.oid
                 WHERE c.relname = '$QUERY$
          || tablename || $QUERY$' AND attnum > 0;$QUERY$;

header := '';
searchsql := $QUERY$SELECT ''$QUERY$;
FOR col IN EXECUTE colsql LOOP
    header := header || '<th>' || col || '</th>';
    searchsql := searchsql || $QUERY$||'<td>'||$QUERY$ || col;
END LOOP;

searchsql := searchsql || ' FROM ' || tablename;

-- rest of your function here

Obviously this gets messy and brittle fast…