How can I display a distinct Field1 and a Field2 that contains the max value for field2?
For example, from the left table get the right table:
| Field1 | Field2 | | Field1 | Field2 |
-------------------- -------------------
| A | 1 | | A | 3 |
| A | 2 | | B | 2 |
| A | 3 | | C | 4 |
| B | 1 | -------------------
| B | 2 |
| C | 1 |
| C | 2 |
| C | 3 |
| C | 4 |
--------------------
I'm a student yet and still a newbie in MySQL :)
select field1, max(field2) as maxf2
from table
group by field1
Related
There are two tables,
Table A has a three-level structure that looks like
| id | name | level | up_level_id |
| :------- | :-------: | :------: | ----------:|
| 1 | lv1_name1 | 1 | null |
| 2 | lv1_name2 | 1 | null |
| 3 | lv2_name1 | 2 | 1 |
| 4 | lv2_name2 | 2 | 2 |
| 5 | lv3_name1 | 3 | 3 |
| 6 | lv3_name2 | 3 | 3 |
| 7 | lv3_name3 | 3 | 4 |
| 8 | lv3_name4 | 3 | 4 |
Table B looks like
| amount | org_id |
| -------- | -------- |
| 12,000 | 5 |
| 15,000 | 6 |
| 20,000 | 7 |
| 18,000 | 8 |
Table A and Table B can be joined on A.id=B.org_id, but they are all at the level-3 of Table A（Only level-3 has their amount）
I want to query the top-level name,level-1 name, and the summary amount that looks like
| sum_amount | top_lvl_name |
| -------- | -------- |
| 27,000 | lv1_name1 |
| 38,000 | lv1_name2 |
For Testing, I have already accomplished the query of the level-1 name from the level-3 id in TableA
The SQL is as follows
SELECT name
FROM TableA
WHERE id IN (
SELECT up_level_id
FROM Table A
WHERE id IN (
SELECT up_level_id
FROM Table A
WHERE id=5) --query the id:5's top-level name
);
But when I join these two tables as follows, it goes wrong
SELECT sum(amount) AS sum_amount, name AS top_lvl_name
FROM TableA, TableB
WHERE id = org_id
AND id IN (
SELECT up_level_id
FROM TableA
WHERE id IN (
SELECT up_level_id
FROM TableA
WHERE TableA.id IN(
SELECT org_id
FROM TABLEB
)
)
);
I get nothing as above
What can I do to make this query to be correct?
Thanks for everyone's answer and comment.
Finally, I find it very difficult to query the result as I wish. So, I've come up with a shortcut——create a new table that a three-level structure recorded horizontally, which looks like
| lv1_id | lv2_name | lv2_id | lv2_name | lv3_id | lv3_name |
| :------- | :-------: | :------: | :----------:| :------: | :----------:|
| 1 | lv1_name1 | 3 | lv2_name1 | 5 | lv3_name1 |
| 1 | lv1_name1 | 3 | lv2_name1 | 6 | lv3_name2 |
| 2 | lv1_name2 | 4 | lv2_name1 | 7 | lv3_name3 |
| 2 | lv1_name2 | 4 | lv2_name1 | 8 | lv3_name4 |
As above,I can easily connect two tables
I want to differentiate duplicate values in my query by adding an increment or a count of some sort.
The idea is to concatenate my two columns to create a new unique reference.
I tried this :
SELECT
value,
COUNT(*) OVER (PARTITION BY value) value_incr
FROM table
and got the following result :
| value | value_incr |
| --- | --- |
| a | 1 |
| b | 3 |
| b | 3 |
| b | 3 |
| c | 2 |
| c | 2 |
| d | 1 |
But what I would like to get is :
| value | value_incr |
| --- | --- |
| a | 1 |
| b | 1 |
| b | 2 |
| b | 3 |
| c | 1 |
| c | 2 |
| d | 1 |
Is there a way to differentiate my duplicates in Oracle 12 ?
My best solution for now is to add a ROWNUM column, but it's not really satisfying.
Thank you
I have a MySQL database including following tables that used to maintain transactions of some documents.
tbl_documents Table
+----+---------+------+---------+
| id | file_no | name | subject |
+----+---------+------+---------+
| 1 | A/10 | F1 | a |
| 2 | A/11 | F2 | b |
| 3 | A/12 | F3 | c |
| 4 | A/13 | F4 | d |
+----+---------+------+---------+
tbl_requests
+----+-------------+----------------+---------------+
| id | document_id | requested_date | approved_date |
+----+-------------+----------------+---------------+
| 1 | 1 | 2019-12-01 | 2019-12-02 |
| 2 | 2 | 2019-12-08 | 2019-12-08 |
+----+-------------+----------------+---------------+
tbl_issues
+----+-------------+------------+
| id | document_id | issue_date |
+----+-------------+------------+
| 1 | 1 | 2019-12-05 |
| 2 | 2 | 2019-12-10 |
+----+-------------+------------+
I want to get the following / Desired output by joining above three tables.
Desired Output
+---------+------+---------+----------------+---------------+------------+
| file_no | name | subject | requested_date | approved_date | issue_date |
+---------+------+---------+----------------+---------------+------------+
| A/10 | F1 | a | 2019-12-01 | 2019-12-02 | 2019-12-05 |
| A/11 | F2 | b | 2019-12-08 | 2019-12-08 | 2019-12-10 |
+---------+------+---------+----------------+---------------+------------+
To do that, I used the following query
select tbl_documents.file_no, tbl_documents.name, tbl_documents.subject, requested_date, approved_date, tbl_issues.issue_date
from tbl_documents
right join tbl_requests on tbl_requests.document_id=tbl_documents.id
right join tbl_issues on tbl_issues.document_id=tbl_documents.id
But didn't get the expected output. Can anyone help ?
Just use inner joins, as in:
select
d.file_no,
d.name,
d.subject,
r.requested_date,
r.approved_date,
i.issue_date
from tbl_documents d
join tbl_requests r on r.document_id = d.id
join tbl_issues i on i.document_id = d.id
Following is my table structure:
+------+----------+
| product | seq |
+------+----------+
| a | 1 |
| b | 1 |
| a | 2 |
| a | 3 |
| b | 2 |
+------+----------+
If my inputs are a and 2 then, i need to change the sequence number and the the output will be
+------+----------+
| product | seq |
+------+----------+
| a | 2 |
| b | 1 |
| a | 1 |
| a | 3 |
| b | 2 |
+------+----------+
am using the logic as :
update mytable SET seq=if(seq=2,1,2), seq=if(seq=1,2,1) where product='a'
But it will not make any changes in the table
Try Like this
UPDATE table1 s1 , table1 s2 SET s1.seq=s2.seq,
s2.seq=s1.seq WHERE s1.seq=2 and s2.seq=1 and
s1.product='a' and s2.product='a';
Is there a way in SQL (MySQL) to do a "round robin" ORDER BY on a particular field?
As an example, I would like to take a table such as this one:
+-------+------+
| group | name |
+-------+------+
| 1 | A |
| 1 | B |
| 1 | C |
| 2 | D |
| 2 | E |
| 2 | F |
| 3 | G |
| 3 | H |
| 3 | I |
+-------+------+
And run a query that produces results in this order:
+-------+------+
| group | name |
+-------+------+
| 1 | A |
| 2 | D |
| 3 | G |
| 1 | B |
| 2 | E |
| 3 | H |
| 1 | C |
| 2 | F |
| 3 | I |
+-------+------+
Note that the table may have many rows, so I can't do the ordering in the application. (I'd obviously have a LIMIT clause as well in the query).
I'd try something like:
SET #counter = 0;
SELECT (#counter:=#counter+1)%3 as rr, grp, name FROM table ORDER by rr, grp
What you can do is create a temporary column in which you create sets to give you something like this:
+-------+------+-----+
| group | name | tmp |
+-------+------+-----+
| 1 | A | 1 |
| 1 | B | 2 |
| 1 | C | 3 |
| 2 | D | 1 |
| 2 | E | 2 |
| 2 | F | 3 |
| 3 | G | 1 |
| 3 | H | 2 |
| 3 | I | 3 |
+-------+------+-----+
To learn how to create the sets, have a look at this question/answer.
Then its a simple
ORDER BY tmp, group, name
You can use MySQL variables to do this.
SELECT grp, name, #row:=#row+1 from table, (SELECT #row:=0) r ORDER BY (#row % 3);
+------+------+--------------+
| grp | name | #row:=#row+1 |
+------+------+--------------+
| 1 | A | 1 |
| 2 | D | 4 |
| 3 | G | 7 |
| 1 | B | 2 |
| 2 | E | 5 |
| 3 | H | 8 |
| 1 | C | 3 |
| 2 | F | 6 |
| 3 | I | 9 |
+------+------+--------------+