Compare two columns and make the insert - sql

Question

I want to compare two columns which come from two different tables.
One of the columns, I need to make SUM for all rows with identity let's say 3 and store to a variable.
After that, compare with one row from other table for same identity 3 and to INSERT something ELSE to BREAK if first_column <= second_column.
Can someone suggest some query for this? For Postgresql...
CREATE OR REPLACE FUNCTION "SA_PRJ".usp_add_timesheet_test(p_uid integer, p_project_id integer, p_allocated_time numeric, p_achieved_time numeric, p_task_desc character varying, p_obs character varying, p_date timestamp without time zone)
RETURNS character varying AS
$BODY$
DECLARE sum_alloc_time numeric;
DECLARE alloc_hours integer;
DECLARE fld_id integer;
DECLARE alloc_id integer;
BEGIN
if not "SA_ADM".usp_check_permission(p_uid, 'SA_PRJ', 'usp_add_timesheet_record') then
raise exception 'User ID % dont have permission!', p_uid;
end if;
select a.fld_id into alloc_id from "SD_PRJ".tbl_project_allocation a where a.fld_emp_id = p_uid and a.fld_project_id = p_project_id;
SELECT SUM(fld_allocated_time)
INTO sum_alloc_time
FROM "SD_PRJ".tbl_project_timesheet
WHERE fld_project_id = p_project_id;
SELECT p.fld_allocated_days, p.fld_id
INTO alloc_hours, fld_id
FROM "SD_PRJ".tbl_project p
JOIN "SD_PRJ".tbl_project_timesheet t USING (fld_id)
WHERE t.fld_project_id = p_project_id;
IF #sum_alloc_time <= #alloc_hours THEN
INSERT INTO "SD_PRJ".tbl_project_timesheet
(fld_emp_id, fld_project_id, fld_is_allocated, fld_allocated_time
, fld_achieved_time, fld_task_desc, fld_obs, fld_date)
VALUES (p_uid, p_project_id, coalesce(alloc_id,0), p_allocated_time
, p_achieved_time, p_task_desc, p_obs, p_date);
RAISE NOTICE 'INSERT OK!';
ELSE
RAISE NOTICE 'NOT OK';
END IF;
END
1.tbl_project (fld_id, fld_allocated_days,fld_project_id)
2.tbl_project_timesheet(fld_id,fld_allocated_time,fld_project_id), all INTEGER
I have this , but dosen't work as I wish.Thanks

Answer 1

I think one problem is here:
SELECT p.fld_allocated_days, p.fld_id
INTO alloc_hours, fld_id
FROM "SD_PRJ".tbl_project p
JOIN "SD_PRJ".tbl_project_timesheet t USING (fld_id)
WHERE t.fld_project_id = p_project_id;
That will cough (I think) whenever the select query returns more than one row i.e. whenever tbl_project_timesheet has more than one record for a fld_id,project_id combination.
Anyway. Here's a partial, simplified answer, but hopefully you get the idea...
I wouldn't use local variables. Do the insert in one step:
INSERT INTO timesheet(emp_id,project_id) -- other columns
SELECT
p_uid,p.fld_project_id -- other columns
FROM
projects p
INNER JOIN
(SELECT SUM(fld_allocated_time) as sumtime
FROM timesheet t WHERE fld_project_id = p_project_id) as sumtime_subquery
ON p.fld_allocated_days < sumtime -- just join on the allocated time
WHERE p.fld_project_id = p_project_id;
Now, you need to know if anything was actually inserted. I think you can use the RETURNING option of the INSERT statement, e.g. from here (caveat - I have never used RETURNING, nor set a local variable from a with statement):
WITH ROWS AS (
INSERT INTO timesheet(emp_id,project_id) -- other columns
SELECT
p_uid,p.fld_project_id -- other columns
FROM
projects p
INNER JOIN
(SELECT SUM(fld_allocated_time) as sumtime
FROM timesheet t WHERE fld_project_id = p_project_id) as sumtime_subquery
ON p.fld_allocated_days < sumtime -- just join on the allocated time
WHERE p.fld_project_id = p_project_id
RETURNING 1
)
SELECT COUNT(*) into l_updatedCount FROM rows; -- you have to declare l_updatedCount
-- Now an if statement to handle l_updatedCount