I am trying to simplify multiple queries into 1 and for some reason I am having issues. I would like to update a reference count in a table while counting the ref in another table. Currently all I have is the _Doc_ID from the first table. I would like to look up the _FilePath and then count the number of rows that have the same _FilePath. Then Update the Ref_Count by the number found.
table 1
| _Doc_ID | Ref_Count |
| 1 | |
table 2
| ID | _FilePath |
| 1 | 123/123 |
| 2 | 123/123 |
Expected Results Table 1
| _Doc_ID | Ref_Count |
| 1 | 2 |
first query
SELECT _FilePath AS FilePathResult from database.tableName where _Doc_ID = '1'
second
SELECT count(*) AS TotalCount from database.tableName where _FilePath = FilePathResult
Third
Update table1 SET Ref_Count = TotalCount where _Doc_ID = 1
UPDATE with sub-query will do.
Update table1
SET Ref_Count =
(
SELECT count(*) AS TotalCount from database.tableName
where _FilePath = (SELECT _FilePath AS FilePathResult from database.tableName where _Doc_ID = '1')
)
where _Doc_ID = 1
Related
I'm currently in the process of converting data from one structure to another, and in the process I have to take a status id from the first entry in the group and apply it to the last entry in that same group. I am able to target and update the last item in the group just fine when using a hard-coded value, but I'm hitting a wall when trying to use the status_id from the first entry. Here is an example of the data structure.
-----------------------------------------------------------
| id | ticket_id | status_id | new_status_id | created_at |
-----------------------------------------------------------
| 1 | 10 | NULL | 3 | 2018-06-20 |
| 2 | 10 | 1 | 1 | 2018-06-22 |
| 3 | 10 | 1 | 1 | 2018-06-23 |
| 4 | 10 | 1 | 1 | 2018-06-26 |
-----------------------------------------------------------
So the idea would be to take the new_status_id of ID 1 and apply it to the same field for ID 4.
Here is the query that works when using a hard-coded value
UPDATE Communications_History as ch
JOIN
(
SELECT communication_id, MAX(created_at) max_time, new_status_id
FROM Communications_History
GROUP BY communication_id
) ch2
ON ch.communication_id = ch2.communication_id AND ch.created_at = ch2.max_time
SET ch.new_status_id = 3
But when I use the following query, I get Unknown column ch.communication_id in where clause
UPDATE Communications_History as ch
JOIN
(
SELECT communication_id, MAX(created_at) max_time, new_status_id
FROM Communications_History
GROUP BY communication_id
) ch2
ON ch.communication_id = ch2.communication_id AND ch.created_at = ch2.max_time
SET ch.new_status_id = (
SELECT nsi FROM
(
SELECT new_status_id FROM Communications_History WHERE communication_id = ch.communication_id AND status_id IS NULL
) as ch3
)
Thanks!
So I just figured it out using variables. It turns out the original "solution" only worked when there was one ticket's worth of history in the table, but when all the data was imported, it no longer worked. However, this tweak did seem to fix the issue.
UPDATE Communications_History as ch
JOIN
(
SELECT communication_id, MAX(created_at) max_time, new_status_id
FROM Communications_History
GROUP BY communication_id
) ch2
ON ch.communication_id = ch2.communication_id AND ch.created_at = ch2.max_time
SET ch.new_status_id = ch2.new_status_id;
I have a table where I store data for different groups and I need to update one group if values in one column are matching.
the table looks like this:
prop_id | group_id | value | visible
1 | 1 | 10 | 1
1 | 2 | 10 | 1
1 | 3 | 15 | 1
2 | 1 | 10 | 1
2 | 2 | 10 | 1
2 | 3 | 10 | 1
So I want to set the visible column to 0 for the group_id=3 if the values in the value column are equal to group_id=1. In this case if value=10 for both group_id=1 and group_id=3 than set visible=0 for group_id=3
expected result after update
prop_id | group_id | value | visible
1 | 1 | 10 | 1
1 | 2 | 10 | 1
1 | 3 | 15 | 1
2 | 1 | 10 | 1
2 | 2 | 10 | 1
2 | 3 | 10 | 0
How is this possible?
Write it as a SELECT first.
Start simple, the rows that we want to update we know are group_id=3 and visible=1, so write a query that gets all of those rows:
SELECT g3.value
, g3.visible
FROM mytable g3
WHERE g3.group_id = 3
AND g3.visible = 1
We know the rows we want to update are in that set, but there are some additional conditions.
So we extend that. According to the spec, we need to find out if there are any matching group_id=1 rows that are visible=1 (matching on value).
We can do that check either with an EXISTS correlated subquery, or we can use a JOIN.
SELECT g3.group_id
, g3.value
, g3.visible
FROM mytable g3
WHERE g3.group_id = 3
AND g3.visible = 1
AND EXISTS ( SELECT 1
FROM mytable g1
WHERE g1.group_id = 1
AND g1.visible = 1
AND g1.value = g3.value
)
-or-
SELECT g3.group_id
, g3.value
, g3.visible
FROM mytable g3
JOIN mytable g1
ON g1.group_id = 1
AND g1.visible = 1
AND g1.value = g3.value
WHERE g3.group_id = 3
AND g3.visible = 1
Verify the query is returning the rows we want to update, under the specific conditions. (It is much easier to verify the results of a SELECT statement, and adjust as necessary, than it is an UPDATE statement.)
Once we have a SELECT query working and verified (returning the rows we want to update) we can convert it into an UPDATE statement. Replace the SELECT ... FROM with UPDATE and add a SET clause that is returning the rows
UPDATE mytable g3
JOIN mytable g1
ON g1.group_id = 1
AND g1.visible = 1
AND g1.value = g3.value
SET g3.visible = 0
WHERE g3.group_id = 3
AND g3.visible = 1
Use Self JOIN then UPDATE
You can try this.
UPDATE T t1
JOIN T t2 on t1.group_id = t2.group_id
and t1.rop_id<>t2.rop_id and t1.value > t2.value
SET t2.visible = 0
sqlfiddle:http://sqlfiddle.com/#!9/6f06de/1
I am trying to combine multiple selects in one query to use as little data as possible.
I have this sql table (example)
id category status
1 test1 A
2 test2 B
3 test1 A
4 test3 B
5 test1 C
First of all i want to select how many rows there is with the same category.
SELECT category, COUNT(category) FROM test GROUP BY category
Then i would like to count the status in each category. I would do this with this query.
SELECT status, COUNT(status) FROM test WHERE category = 'test1' GROUP BY STATUS
So i want one column with total and then each categorys number of status.
Can i somehow combine these? Is that even possible or do i just have to realize that I have to get the data multiple times to have the right result?
You can try to GROUP BY category and by status and use WITH ROLLUP to get aggregate values:
SELECT category, status, count(*)
FROM test
GROUP BY category, status WITH ROLLUP
The result will look like this:
category | status | count(*)
----------+--------+----------
test1 | A | 2
test1 | C | 1
test1 | NULL | 3
test2 | B | 1
test2 | NULL | 1
test3 | B | 1
test3 | NULL | 1
NULL | NULL | 5
If you ignore the rows containing NULLs, the rest is the regular GROUP BY category, status. There are 2 entries having category = 'test1' AND status = 'A', one entry having category = 'test1' AND status = 'C' and so on.
The third row of the result (category = 'test1', status = NULL, count(*) = 3) summarizes the rows having category = 'test1'. It computes count(*) for all the rows having category = 'test1' no matter what value they have in column status. In a similar way there are computed the summary rows for category = 'test2' and category = 'test3'.
The last row is the summary for the entire table. count(*) = 5 includes all the rows, no matter what value they have in columns category and status.
You can run your second query for all categories at once like this:
mysql> select category, status, count(*) from foo group by category, status;
+----------+--------+----------+
| category | status | count(*) |
+----------+--------+----------+
| test1 | A | 2 |
| test1 | C | 1 |
| test2 | B | 1 |
| test3 | B | 1 |
+----------+--------+----------+
4 rows in set (0.39 sec)
And then you could compute the category-wide count by summing up all its rows. If you really want that too as part of the same query, you could do this:
mysql> select foo.category, status, count(*), cat_count
-> from foo
-> inner join (select category, count(*) cat_count from foo group by category) x
-> on x.category = foo.category
-> group by foo.category, status;
+----------+--------+----------+-----------+
| category | status | count(*) | cat_count |
+----------+--------+----------+-----------+
| test1 | A | 2 | 3 |
| test1 | C | 1 | 3 |
| test2 | B | 1 | 1 |
| test3 | B | 1 | 1 |
+----------+--------+----------+-----------+
4 rows in set (0.00 sec)
Unfortunately MySQL does not support window functions.
One way would be to get your status counts for each category in one query:
SELECT
category,
status,
COUNT(*) AS status_count
FROM
test
GROUP BY
category, status
And then INNER JOIN information about count for categories to it like that:
SELECT
a.*, b.category_count
FROM (
SELECT
category,
status,
COUNT(*) AS status_count
FROM
test
GROUP BY
category, status
) a
INNER JOIN ( SELECT category, COUNT(*) AS category_count FROM test GROUP BY category ) b ON
a.category = b.category
I just added the 'default' column to my DB. I am trying to set the default value to '1' based on the latest 'addDate' per accountId.
+----+-----------+--------------------+--------+
| id | accountId | addDate | default|
+----+-----------+--------------------+--------+
| 1 | 45 |2012-02-29 08:41:59 | |
| 2 | 55 |2012-03-29 08:41:59 | |
| 3 | 45 |2012-04-29 08:41:59 | |
| 4 | 55 |2012-05-29 08:41:59 | |
| 5 | 60 |2012-05-29 08:41:59 | |
+----+-----------+--------------------+--------+
I found I was able to isolate the proper rows by using =>
select * from tble1
where addDate = (select max(addDate) from tble1 as sl where sl.accountId = tble1.accountId);
I need to be able to run an UPDATE that sets 'default' column to '1' only 1 time per 'accountId' basing it off of latest 'addDate'.
try this
UPdate Table1
SET `default` = 1
where addDate in (select * from (
select max(addDate) from table1 as sl group by accountId)t
)
DEMO HERE
UPDATE table1 x
LEFT
JOIN table1 y
ON y.accountid = x.accountid
AND y.adddate > x.adddate
SET x.default = 1
WHERE y.id IS NULL;
or (faster)
UPDATE table1 x
JOIN
( SELECT accountid
, MAX(addDate) max_adddate
FROM table1
GROUP
BY accountid
) y
ON y.accountId = x.accountId
AND y.max_adddate = x.adddate
SET x.default = 1;
Firstly, pardon the incredibly vague/long question, I'm really not sure how to summarise my query without the full explanation.
Ok, I have a single MySQL table with the format like so
some_table
user_id
some_key
some_value
If you imagine that, for each user, there are multiple rows, for example:
1 | skill | html
1 | skill | php
1 | foo | bar
2 | skill | html
3 | skill | php
4 | foo | bar
If I want to find all the users who have listed HTML as a skill I can simply do:
SELECT user_id
FROM some_table
WHERE some_key = 'skill' AND some_value='html'
GROUP BY user_id
Easy enough. This would give me user ID's 1 and 2.
If I want to find all users who have listed HTML or PHP as a skill then I can do:
SELECT user_id
FROM some_table
WHERE (some_key = 'skill' AND some_value='html') OR (some_key = 'skill' AND some_value='php')
GROUP BY user_id
This would give me use ID's 1, 2 and 3.
Now, what I'm struggling to work out is how I can query the same table but this time say "give me all the users who have listed both HTML and PHP as a skill", i.e: just user ID 1.
Any advice, guidance or links to docs massively appreciated.
Thanks.
Here's one way:
SELECT user_id
FROM some_table
WHERE user_id IN (SELECT user_id FROM some_table where (some_key = 'skill' AND some_value='html'))
AND user_id IN (SELECT user_id FROM some_table where (some_key = 'skill' AND some_value='php'))
you need to use a nested query (or a self join, which is different)
I set up the following table.
+-------+----------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+----------+------+-----+---------+-------+
| id | int(11) | YES | | NULL | |
| type | char(10) | YES | | NULL | |
| value | char(10) | YES | | NULL | |
+-------+----------+------+-----+---------+-------+
inserted the following values
+------+-------+-------+
| id | type | value |
+------+-------+-------+
| 1 | skill | html |
| 1 | skill | php |
| 2 | skill | html |
| 3 | skill | php |
| 2 | skill | php |
+------+-------+-------+
ran this query
select id
from test
where type = 'skill'
and value = 'html'
and id in (
select id
from test
where type = 'skill'
and value = 'php');
and got
+------+
| id |
+------+
| 1 |
| 2 |
+------+
a self join would be as follows
select e1.id
from test e1, test e2
where e1.id = e2.id
and e2.type = 'skill'
and e2.value = 'html'
and e1.type = 'skill'
and e1.value = 'php'
;
and produce the same result.
so there you have two ways to try it in your code.
I don't know if this is valid for mysql, but should be (works for other db engines):
SELECT php.user_id
FROM some_table php, some_table html
WHERE php.user_id = html.user_id
AND php.some_key = 'skill'
AND html.some_key = 'skill'
AND php.some_value = 'php'
AND html.some_value = 'html';
And alternative, by using HAVING statement:
SELECT user_id, count(*)
FROM some_table
WHERE some_key = 'skill'
AND some_value in ('php','html')
GROUP BY user_id
HAVING count(*) = 2;
And a third option is to use inner selects. A slight alternative approach to David's approach:
SELECT user_id FROM some_table
WHERE
some_key = 'skill' AND
some_value = 'html' AND
user_id IN (
SELECT user_id FROM some_table
WHERE
some_key = 'skill' AND
some_value = 'php' AND
user_id IN (
SELECT user_id FROM some_table
WHERE
some_key = 'skill' AND
some_value = 'js' -- AND user_id IN ... for next level, etc.
)
);
... idea is that you can "pipe" the inner selects. With each new property you add new inner select to the most inner one.