I have a table t1
+-----+-------+------+
| id | tID | cID |
+-----+-------+------+
| 1 | 1 | 0 |
| 2 | 1 | 1 |
| 3 | 1 | 4 |
| 4 | 1 | 2 |
| 1 | 2 | 3 |
| 2 | 2 | 2 |
+-----+-------*------*
I have deleted a record where tID is 1 and id is 3 and cID is 4,
now I want that sequence to get updated like record with id 4 gets sequence 3
below is the sample data.
+-----+-------+------+
| id | tID | cID |
+-----+-------+------+
| 1 | 1 | 0 |
| 2 | 1 | 1 |
| 3 | 1 | 2 |
| 1 | 2 | 3 |
| 2 | 2 | 2 |
+-----+-------+------+
Can I get an updated statement for this problem? How can I achieve this in Postgres?
Given that you know which record you just deleted you can update like this:
UPDATE t1 SET id = id - 1 where id > 3 and tID = 1;
First off presuming that id is (or part of) the Primary Key, this is a very very bad idea. The Primary key really ought to be IMMUTABLE. But if you insist on perusing it then at least do delete and update in a single step. Create an SQL function that handles both: (see fiddle)
create or replace
function remove_from_table1(id_in integer, tid_in integer)
returns void
language sql
as $$
with bye_bye (id, tid) as
( delete
from table1 d
where d.id = id_in
and d.tid = tid_in
returning id, tid
)
update table1 u
set id = u.id - 1
from bye_bye
where u.tid = bye_bye.tid
and u.id > bye_byeid;
$$;
That way later development (developers) would not need to make two separate calls, to complete the task. Even further I would put the function into a protected schema. Revoke delete authority from all schema except the owner. Grant execute of the function as needed. That protects the table from forgetting to call the function and issuing a direct delete.
Related
I have two similar tables with different values:
users_groups_old
user_id | group_id | rating | registered
----------------------------------------
1 | 1 | 1 |
1 | 2 | 2 |
2 | 2 | 3 |
users_groups
user_id | group_id | rating | registered
----------------------------------------
1 | 1 | 10 |
1 | 2 | 20 |
I want to "merge" two tables or sum the rating if the row already exists.
Finally I want to get the following table (table key is: user_id + group_id):
users_groups
user_id | group_id | rating | registered
----------------------------------------
1 | 1 | 11 |
1 | 2 | 22 |
2 | 2 | 3 |
I trying the following
insert into users_groups
select *
from users_groups_old
on conflict (user_id, group_id)
do update
set rating = users_groups.rating + excluded.rating;
But got the error
SQL Error [42P10]: ERROR: there is no unique or exclusion constraint matching the ON CONFLICT specification
Which I can't understand, what I am doing wrong?
It seems that the database cannot identify the unique constraint for (user_id, group_id). Please check if it is defined correctly and try using the constraint name directly:
...
on conflict on constraint <constraint name>
...
I have a table of users that has a column called order that represents the order in they will be elected.
So, for example, the table might look like:
| id | name | order |
|-----|--------|-------|
| 1 | John | 2 |
| 2 | Mike | 0 |
| 3 | Lisa | 1 |
So, say that now Lisa gets destroyed, I would like that in the same transaction that I destroy Lisa, I am able to update the table so the order is still consistent, so the expected result would be:
| id | name | order |
|-----|--------|-------|
| 1 | John | 1 |
| 2 | Mike | 0 |
Or, if Mike were the one to be deleted, the expected result would be:
| id | name | order |
|-----|--------|-------|
| 1 | John | 1 |
| 3 | Lisa | 0 |
How can I do this in PostgreSQL?
If you are just deleting one row, one option uses a cte and the returning clause to then trigger an update
with del as (
delete from mytable where name = 'Lisa'
returning ord
)
update mytable
set ord = ord - 1
from del d
where mytable.ord > d.ord
As a more general approach, I would really recommend trying to renumber the whole table after every delete. This is inefficient, and can get tedious for multi-rows delete.
Instead, you could build a view on top of the table:
create view myview as
select id, name, row_number() over(order by ord) ord
from mytable
I need help with updating table from another table in Postgres Db.
Long story short we ended up with corrupted data in db, and now I need to update one table with values from another.
I have table with this data table wfc:
| step_id | command_id | commands_order |
|---------|------------|----------------|
| 1 | 1 | 0 |
| 1 | 2 | 1 |
| 1 | 3 | 2 |
| 1 | 4 | 3 |
| 1 | 1 | 0 |
| 2 | 2 | 0 |
| 2 | 3 | 1 |
| 2 | 3 | 1 |
| 2 | 4 | 3 |
and I want to update values in command_order column from another table, so I can have result like this:
| step_id | command_id | commands_order|
|---------|------------|---------------|
| 1 | 1 | 0 |
| 1 | 2 | 1 |
| 1 | 3 | 2 |
| 1 | 4 | 3 |
| 1 | 1 | 4 |
| 2 | 2 | 0 |
| 2 | 3 | 1 |
| 2 | 3 | 2 |
| 2 | 4 | 3 |
It was looking like easy task, but problem is to update rows for same command_id, it is writing same value in commands_order
SQL that I tried is:
UPDATE wfc
SET commands_order = CAST(sq.input_step_id as INTEGER)
FROM (
SELECT wfp.step_id, wfp.input_command_id, wfp.input_step_id
from wfp
order by wfp.step_id, wfp.input_step_id
) AS sq
WHERE (wfc.step_id=sq.step_id AND wfc.command_id=CAST(sq.input_command_id as INTEGER));
SQL Fiddle http://sqlfiddle.com/#!15/4efff4/4
I am pretty stuck with this, please help.
Thanks in advance.
Assuming you are trying to number the rows in the order in which they were created, and as long as you understand that ctid will chnage on update and with VACCUUM FULL, you can do the following:
select step_id, command_id, rank - 1 as command_order
from (select step_id, command_id, ctid as wfc_ctid, rank() over
(partition by step_id order by ctid)
from wfc) as wfc_ordered;
This will give you the wfc table with the ordering that you want. If you do update the original table, the ctids will change, so it's probably safer to create a copy of the table with the above query.
I have a next table sample, called userz:
+----+---------------+----------+
| id | sort_position | type |
+----+---------------+----------+
| 1 | -5 | admin |
| 2 | -3 | customer |
| 3 | 1 | customer |
| 4 | 8 | employee |
| 5 | 200 | customer |
+----+---------------+----------+
With Mysql If i want to make sort_position of all customer type to start from 0 and ++ until the last row that satisfies WHERE criteria, i can do next:
SET #i=-1;
UPDATE userz
SET sort_position=#i:=#i+1
WHERE type = "customer" ORDER BY sort_position;
and i would receive expected result:
+----+---------------+----------+
| id | sort_position | type |
+----+---------------+----------+
| 1 | -5 | admin |
| 2 | 0 | customer |
| 3 | 1 | customer |
| 4 | 8 | employee |
| 5 | 2 | customer |
+----+---------------+----------+
as you see all customers are now assigned with correct sort_position of 0,1,2
But since i'm working with postgre i need to reach same with it. What i tried so far:
DO $$
DECLARE
i integer := -1;
BEGIN
UPDATE userz
SET sort_position=#i:=#i+1
WHERE type = "customer" ORDER BY sort_position;
END $$;
and i have errors around =#i:=#i+1 , tried different formatting that i googled like =i:=i+1 but still no luck.
Try below SQL;
update userz k
set sort_position =
(select ROW_NUMBER() over(order by sort_position)-1 rnum
from userz src
where src.type ='customer'
and id = k.id)
I have the following tables:
user_group
usergrp_id bigint Primary Key
usergrp_name text
user
user_id bigint Primary Key
user_name text
user_usergrp_id bigint
user_loc_id bigint
user_usergrp_id has its corresponding id from the user_group table
user_loc_id has its corresponding id(branch_id) from the branch table.
branch
branch_id bigint Primary Key
branch_name text
branch_type smallint
branch_type By default is set as 1. Although it may contain any value in between 1 and 4.
user_projects
proj_id bigint Primary Key
proj_name text
proj_branch_id smallint
proj_branch_id has its corresponding id(branch_id) from the branch table.
user_approval
appr_id bigint Primary Key
appr_prjt_id bigint
appr_status smallint
appr_approval_by bigint
appr_approval_by has its corresponding id(user_id) from the user table
appr_status may contain different status values like 10,20,30... for a single appr_prjt_id
user_group
usergrp_id | usergrp_name
-------------------------
1 | Admin
2 | Manager
user
user_id | user_name | user_usergrp_id |user_loc_id
---------------------------------------------------
1 | John | 1 | 1
2 | Harry | 2 | 1
branch
branch_id | branch_name | branch_type
-------------------------------------
1 | location1 | 2
2 | location2 | 1
3 | location3 | 4
4 | location4 | 2
5 | location4 | 2
user_projects
proj_id | proj_name | proj_branch_id
------------------------------------
1 | test1 | 1
2 | test2 | 2
3 | test3 | 1
4 | test4 | 3
5 | test5 | 1
6 | test5 | 4
user_approval
appr_id | appr_prjt_id | appr_status | appr_approval_by
-------------------------------------------------------
1 | 1 | 10 | 1
2 | 1 | 20 | 1
3 | 1 | 30 | 1
4 | 2 | 10 | 2
5 | 3 | 10 | 1
6 | 3 | 20 | 2
7 | 4 | 10 | 1
8 | 4 | 20 | 1
Condition: The output must take the MAX() value of appr_status for each appr_prjt_id and count it.
I.e., in the above table appr_prjt_id=1 has 3 different status: 10, 20, 30. Its count must only be shown for status corresponding to 30 in the output (not in the statuses 10 and 20), corresponding to a user group in a particular branch_name. Similarly for each of the other id's in the field appr_prjt_id
SQL Fiddle
Desired Output:
10 | 20 | 30
------> Admin 0 | 1 | 1
|
location1
|
------> Manager 1 | 1 | 0
How can I do that?
SQL Fiddle
SQL Fiddle
select
branch_name, usergrp_name,
sum((appr_status = 10)::integer) "10",
sum((appr_status = 20)::integer) "20",
sum((appr_status = 30)::integer) "30"
from
(
select distinct on (appr_prjt_id)
appr_prjt_id, appr_approval_by, appr_status
from user_approval
order by 1, 3 desc
) ua
inner join
users u on ua.appr_approval_by = u.user_id
inner join
user_group ug on u.user_usergrp_id = ug.usergrp_id
inner join
branch b on u.user_loc_id = b.branch_id
group by branch_name, usergrp_name
order by usergrp_name
The classic solution, that works in most DBMSs is to use a case:
select
branch_name, usergrp_name,
sum(case appr_status when 10 then 1 else 0 end) "10",
But Postgresql has the boolean type and it has a cast to integer (boolean::integer) resulting in 0 or 1 which makes for less verbose code.
In this case it is also possible to do a count in instead of a sum:
select
branch_name, usergrp_name,
count(appr_status = 10 or null) "10",
I indeed prefer the count but I have the impression that it is harder to understand. The trick is to know that count counts anything not null and that a (true or null) is true and a (false or null) is null so it will count whenever the condition is true.