Title is confusing I know, I'm just not sure how to word this. Anyway let me describe with a table:
| key | column b | column c |
|-----|----------|----------|
| a | 13 | 2 |
| a | 14 | 2 |
| a | 15 | 1 |
| b | 16 | 2 |
| b | 17 | 2 |
I'd like to select all keys where column c doesn't equal 1, so the select will result in returning only key 'b'
To clarify, my result set should not contain keys that have a row where column c is set to 1. Therefore I'd like a sql query that would return the keys that satisfy the previous statement.
To make my question as clear as possible. From the table above, what I want returned by some sql statement is a result set containing [{b}] based on the fact that key 'a' has at least one row where column c is equal to 1 whereas key 'b' does not have any rows that contain 1 in column c.
SELECT t.[Key]
FROM TableName t
WHERE NOT EXISTS (SELECT 1
FROM TableName
WHERE t.[key] = [key]
AND ColumnC = 1)
GROUP BY t.[Key]
SELECT KEY
FROM WhateverYourTableNameIs
WHERE c <> '1'
I would do this using group by and aggregation:
select [key]
from table t
group by [key]
having sum(case when c = 1 then 1 else 0 end) = 0;
The having clause counts the number of rows that have c = 1. The = 0 says that there are no such rows for a given key.
Elaboration based on other comments:
You asked for ALL keys where column c doesn't equal 1. That is exactly what the query I suggested will give you. The other part of your question so the SELECT will result in returning only key 'b', is ambiguous. The question as asked will give you results from columns A and B. There is nothing in your question to limit the result set. You either need an additional condition to your WHERE clause, or your question is inherently unanswerable.
Related
I have a SQL table in the form of:
| value | row_loc | column_loc |
|-------|---------|------------|
| a | 0 | 1 |
| b | 1 | 1 |
| c | 1 | 0 |
| d | 0 | 0 |
I would like to find a way to map it onto a table/grid, given the indices, using SQL. Something like:
| d | a |
| c | b |
(The context being, I would like to create a colour map with colours corresponding to values a, b, c, d, in the locations specified)
I would be able to do this iteratively in python, but cannot figure out how to do it in SQL, or if it is even possible! Any help or guidance on this problem would be greatly appreciated!
EDIT: a, b, c, d are examples of numeric values (which would not be able to be selected using named variables in practice, so I'm relying on selecting them based on location. Also worth noting, the number of rows and columns will always be the same. The value column is also not the primary key to this table, so is not necessarily unique, it is just as a continuous value.
Yes, it is possible, assuming the column number is limited since SQL supports only determined number of columns. The number of rows in result set depends on number of distinct row_loc values so we have to group by column row_loc. Then choose value using simple case.
with t (value, row_loc, column_loc) as (
select 'a', 0, 1 from dual union all
select 'b', 1, 1 from dual union all
select 'c', 1, 0 from dual union all
select 'd', 0, 0 from dual
)
select max(case column_loc when 0 then value else null end) as column0
, max(case column_loc when 1 then value else null end) as column1
from t
group by row_loc
order by row_loc
I tested it on Oracle. Not sure what to do if multiple values match on same coordinate, I chose max. For different vendors you could also utilize special clauses such as count ... filter (where ...). Or the Oracle pivot clause can also be used.
I have 2 tables A and B. I need to update a column in table A for all userid's based on the count of records that userid has in another table based on defined rules. If count of records in another table is 3 and is required for that userID, then mark IsCorrect as 1 else 0, if count is 2 and required is 5 then IsCorrect as 0 For e.g. Below is what I am trying to achieve
Table A
UserID | Required | IsCorrect
----------------------------------
1 | SO;GO;PE | 1
2 | SO;GO;PE;PR | 0
3 | SO;GO;PE | 1
Table B
UserID | PPName
-----------------------
1 | SO
1 | GO
1 | PE
2 | SO
2 | GO
3 | SO
3 | GO
3 | PE
I tried using Update in table joining another table, but cannot up with one. Also, do not want to use cursors, because of its overhead. I know I will have to create a stored Procedure for it for the rules, but how to pass the userID's to it without cursor is what am i am looking for.
Thanks for the help. Apologies for not formatting the table correctly :)
update A
set IsCorrect = case
when Required <= (select count(*) from B where b.UserID = A.UserID)
then 'Y' -- or 0, or whatever sense is appropriate
else 'N'
end
THIS ANSWERS THE ORIGINAL QUESTION.
Hmmm, you can use a correlated subquery and some case logic:
update a
set iscorrect = (case when required <=
(select count(*) from b where b.userid = a.userid)
then 1 else 0
end);
Is there a build in function in sql, to reverse the order in which the groupby works? I try to groupby a certain key but i would like to have the last inserted record returned and not the first inserted record.
Changing the order with orderby does not affect this behaviour.
Thanx in advance!
EDIT:
this is the sample data:
id|value
-----
1 | A
2 | B
3 | B
4 | C
as return i want
1 | A
3 | B
4 | C
not
1 | A
2 | B
4 | C
when using group by id don't get the result i want.
Question here is how are you identifying last inserted row. Based on your example, it looks like based on id. If id is auto generated, or a sequence then you can definitely do this.
select max(id),value
from your_table
group by value
Ideally in a table design, people uses a date column which holds the time a particular record was inserted, so it is easy to order by that.
Use Max() as your aggregate function for your id:
SELECT max(id), value FROM <table> GROUP BY value;
This will return:
1 | A
3 | B
4 | C
As for eloquent, I've not used it but I think it would look like:
$myData = DB::table('yourtable')
->select('value', DB::raw('max(id) as maxid'))
->groupBy('value')
->get();
I have an SQLite question which essentially boils down to the following problem.
id | key | data
1 | A | x
2 | A | x
3 | B | x
4 | B | x
5 | A | x
6 | A | x
New data is appended to the end of the table with an auto-incremented id.
Now, I want to create a query which returns the latest row for each key, like this:
id | key | data
4 | B | x
6 | A | x
I've tried some different queries but I have been unsuccessful. How do you select only the latest rows for each "key" value in the table?
use this SQL-Query:
select * from tbl where id in (select max(id) from tbl group by key);
You could split the main task into two subroutine.
You could move with the approach first retrieve all id/key value then get the id for the latest value of A and B keys,
Now you could easly write a query to get latest value for A and B because you have value of id's for both A and B keys.
SELECT *
FROM mytable
JOIN
( SELECT MAX(id) AS maxid
FROM mytable
GROUP BY "key"
) AS grp
ON grp.maxid = mytable.id
Side note: it's best not to use reserved words like keyas identifiers (for tables, fields. etc.)
Without nested SELECTs, or JOINs but only if the field determining "newest" is primary key (e.g. autoincrement):
SELECT * FROM table GROUP BY key DESC;
In PostgreSQL 8.3, let's say I have a table called widgets with the following:
id | type | count
--------------------
1 | A | 21
2 | A | 29
3 | C | 4
4 | B | 1
5 | C | 4
6 | C | 3
7 | B | 14
I want to remove duplicates based upon the type column, leaving only those with the highest count column value in the table. The final data would look like this:
id | type | count
--------------------
2 | A | 29
3 | C | 4 /* `id` for this record might be '5' depending on your query */
7 | B | 14
I feel like I'm close, but I can't seem to wrap my head around a query that works to get rid of the duplicate columns.
count is a sql reserve word so it'll have to be escaped somehow. I can't remember the syntax for doing that in Postgres off the top of my head so I just surrounded it with square braces (change it if that isn't correct). In any case, the following should theoretically work (but I didn't actually test it):
delete from widgets where id not in (
select max(w2.id) from widgets as w2 inner join
(select max(w1.[count]) as [count], type from widgets as w1 group by w1.type) as sq
on sq.[count]=w2.[count] and sq.type=w2.type group by w2.[count]
);
There is a slightly simpler answer than Asaph's, with EXISTS SQL operator :
DELETE FROM widgets AS a
WHERE EXISTS
(SELECT * FROM widgets AS b
WHERE (a.type = b.type AND b.count > a.count)
OR (b.id > a.id AND a.type = b.type AND b.count = a.count))
EXISTS operator returns TRUE if the following SQL statement returns at least one record.
According to your requirements, seems to me that this should work:
DELETE
FROM widgets
WHERE type NOT IN
(
SELECT type, MAX(count)
FROM widgets
GROUP BY type
)