Error in Insert function in postgresql - postgresql-9.1

Question

CREATE OR REPLACE FUNCTION InsertInformation
(
p_Name varchar(20)
,p_Address varchar(250)
,p_Mobile int
) RETURNS VOID
as $$
begin
declare v_ID int;
BEGIN
select coalesce(max(Id),0) into v_ID from Information
set; v_ID=v_ID+1
insert into Information
(
Id
,Name
,Address
,Mobile
)
values
(
v_ID
,p_Name
,p_Address
,p_Mobile
)
select v_ID;
$$
LANGUAGE plpgsql;
I convert my sql insert sp to Postgres function using online converter tool but it showing the below mention error
error showing : ERROR: syntax error at or near "insert"
LINE 16: insert into Information

Answer 1

This:
select coalesce(max(Id),0) into v_ID from Information
set; v_ID=v_ID+1
Is wrong.
The select isn't properly terminated, and the set itself is illegal syntax.
You probably want this:
select coalesce(max(Id),0)
into v_ID
from Information; --<< terminate with a ; here
v_id := v_id + 1; --<< terminate with a ; here
But the extra assignment isn't necessary in the first place. The above can be shortened to:
select coalesce(max(Id),0) + 1
into v_ID
from Information;
This
select v_ID;
is also wrong. To return a value use:
return v_id;
But your function is defined as returns void so you can't return anything in the first place.
But: using select coalesce(max(Id),0) + 1 to generate unique IDs is wrong and will not work correctly in a real world application.
The only correct, scalable and fast way to generate new ids is to use a sequence. Really.
The complete function (if you want to return the newly "generated" id) would look like this:
CREATE OR REPLACE FUNCTION InsertInformation(p_Name varchar(20),p_Address varchar(250),p_Mobile int)
RETURNS integer
as
$$
declare
v_ID int;
BEGIN
select coalesce(max(Id),0) + 1
into v_ID
from Information;
INSERT INTO information
(id, name, address, mobile)
VALUES
(v_id, p_name, p_address, p_mobile);
return v_id;
END;
$$
LANGUAGE plpgsql;
SQLFiddle example: http://sqlfiddle.com/#!15/4ac27/1