PostgreSQL 9.3: missing FROM-clause entry for table - postgresql

Question

I have a table with two columns.
Example:
create table t1
(
cola varchar,
colb varchar
);
Now I want to insert the rows from function.
In the function: I want to use two parameters which is of type varchar to insert the values into the above table. I am passing the string to insert into the table.
I am passing two string of characters as a parameters to the function:
Parameters:
cola varchar = 'a,b,c,d';
colb varchar = 'e,f,g,h';
The above parameters have to insert into the table like this:
cola colb
----------------
a e
b f
c g
d h
My try:
create or replace function fun_t1(cola varchar,colb varchar)
returns void as
$body$
Declare
v_Count integer;
v_i integer = 0;
v_f1 text;
v_cola varchar;
v_colb varchar;
v_query varchar;
Begin
drop table if exists temp_table;
create temp table temp_table
(
cola varchar,
colb varchar
);
v_Count := length(cola) - length(replace(cola, ',', ''));
raise info '%',v_Count;
WHILE(v_i<=v_Count) LOOP
INSERT INTO temp_table
SELECT LEFT(cola,CHARINDEX(',',cola||',',0)-1)
,LEFT(colb,CHARINDEX(',',colb||',',0)-1);
cola := overlay(cola placing '' from 1 for CHARINDEX(',',cola,0));
colb := overlay(colb placing '' from 1 for CHARINDEX(',',colb,0));
v_i := v_i + 1;
END LOOP;
for v_f1 IN select * from temp_table loop
v_cola := v_f1.cola; /* Error occurred here */
v_colb := v_f1.colb;
v_query := 'INSERT INTO t1 values('''||v_cola||''','''||v_colb||''')';
execute v_query;
end loop;
end;
$body$
language plpgsql;
Note: In the function I have used temp_table that is according to the requirement which
I am using for the other use also in the function which I have not display here.
Calling function:
SELECT fun_t1('a,b,c','d,e,f');
Getting an error:
missing FROM-clause entry for table "v_f1"

Answer 1

Try this way using split_part() : -
create or replace function ins_t1(vala varchar,valb varchar,row_cnt int) returns void as
$$
BEGIN
FOR i IN 1..row_cnt LOOP -- row_cnt is the number rows you need to insert (ex. 4 or 5 or whatever it is)
insert into t1 (cola,colb)
values (
(select split_part(vala,',',i))
,(select split_part(valb,',',i))
);
END LOOP;
END;
$$
language plpgsql
function call :select ins_t1('a,b,c,d','e,f,g,h',4)
As mike-sherrill-cat-recall said in his answer by using regexp_split_to_table
create or replace function fn_t1(vala varchar,valb varchar) returns void
as
$$
insert into t1 (cola, colb)
select col1, col2 from (select
trim(regexp_split_to_table(vala, ',')) col1,
trim(regexp_split_to_table(valb, ',')) col2)t;
$$
language sql
function call :select fn_t1('a,b,c,d','e,f,g,h')

Answer 2

If there's no compelling reason to use a function for this, you can just split the text using a regular expression. Here I've expressed your arguments as a common table expression, but that's just for convenience.
with data (col1, col2) as (
select 'a, b, c, d'::text, 'e, f, g, h'::text
)
select
trim(regexp_split_to_table(col1, ',')) as col_a,
trim(regexp_split_to_table(col2, ',')) as col_b
from data;
col_a col_b
--
a e
b f
c g
d h
If there is a compelling reason to use a function, just wrap a function definition around that SELECT statement.
create function strings_to_table(varchar, varchar)
returns table (col_a varchar, col_b varchar)
as
'select trim(regexp_split_to_table($1, '','')),
trim(regexp_split_to_table($2, '',''));'
language sql
stable
returns null on null input;
select * from strings_to_table('a,b,c,d', 'e,f, g, h');
col_a col_b
--
a e
b f
c g
d h
My personal preference is usually to build functions like this to return tables rather than inserting into tables. To insert, I'd usually write a SQL statement like this.
insert into foo (col_a, col_b)
select col_a, col_b from strings_to_table('a,b,c,d', 'e,f,g,h');

Answer 3

The simpest way is using plpython for this.
create or replace function fill_t1(cola varchar, colb varchar) returns void as $$
for r in zip(cola.split(','), colb.split(',')):
plpy.execute(plpy.prepare('insert into t1(cola, colb) values ($1, $2)', ['varchar', 'varchar']), [r[0], r[1]])
$$ language plpythonu;
The result:
# create table t1 (cola varchar, colb varchar);
CREATE TABLE
# select fill_t1('1,2,3', '4,5,6');
fill_t1
---------
(1 row)
# select * from t1;
cola | colb
------+------
1 | 4
2 | 5
3 | 6
(3 rows)
You can read about Python zip function here: https://docs.python.org/2/library/functions.html#zip