I got two tables that contain date and time stamps and trying to extract records by the latest date in both.
Table 1 (sessions):
id---login_date------------ip
01---2014-01-02 23:58:40---127.0.0.1
03---2014-01-01 13:20:16---127.0.0.1
01---2014-01-01 17:06:15---127.0.0.1
02---2013-12-30 14:34:39---127.0.0.1
*also multiple other non-date columns which are not playing part in this solution
Table 2 (reminders):
id---last_reminder---------next_reminder
03---2013-12-29 22:50:18---2014-01-07 22:50:18
02---2014-01-01 15:15:15---2014-01-09 15:15:15
02---2013-11-16 08:54:23---2013-11-23 08:54:23
Now this is the way I get all the latest logins from the first table for each user ID:
SELECT a.id, a.login_date
FROM sessions a
WHERE a.login_date = (
SELECT max(login_date) as login_date
FROM sessions
WHERE id = a.id
LIMIT 1
)
GROUP BY a.id
What I would like to get is not only the last login date for each user ID, but also the last sent reminder (if any). As this involves selecting two max dates I never get correct results.
Desired Result:
id---login_date------------last_reminder---------next_reminder------
01---2014-01-02 23:58:40---NULL------------------NULL---------------
02---2013-12-30 14:34:39---2014-01-01 15:15:15---2014-01-09 15:15:15
03---2014-01-01 13:20:16---2013-12-29 22:50:18---2014-01-07 22:50:18
Would anybody please help me out with this.
Thanks,
Simon
////////////////////////UPDATED 2014-01-04 WITH EXTRA COLUMNS////////////////////////////
Based on the request the above table structure was updated to contain extra fields, required to produce correct query results.
*note that next_reminder field will always have a value as it's calculated based on the last reminder value. The query will eventually check whether the next reminder is within certain timeframe too.
P.S. StackOverflow is full of very good answers when only one table contains the date and time stamp (from which I have built what I have got so far), however I could not locate any similar examples that would involve joining two tables and selecting max dates from each.
if you have only two columns per table, you can directly join it and use MAX() to get the latest record for each ID.
SELECT a.id,
MAX(login_date) latest_login_date,
MAX(last_reminder) latest_reminder
FROM sessions a
LEFT JOIN reminders b
ON a.id = b.id
GROUP BY a.id
SQLFiddle Demo
Related
I'm new to SQL as for over 20 years I haven't touched a single code line, so it feels like starting over.
I have a database with two tables, one for Projects, and another one for the Milestones. What I'm trying to achieve is to have a query that will retrieve the latest Milestone logged for each project. That way I can build a report with one project line with the latest update only.
I've managed to build the query to retrieve 1 (One) Milestone Record for each project. However when I've logged more than one update for the same date, the query returns all of them. I've tried to utilize the rowid, but it didn't work.
Here my sample tables:
And the query I've tried to run that currently retrieves more than 1 record when milestone created the same date.
select PROJECT_DATA.PARTNER_NAME as PARTNER_NAME,
PROJECT_DATA.SOLUTION_STATUS as SOLUTION_STATUS,
PROJECT_DATA.STRATEGY_MANAGER as STRATEGY_MANAGER,
PROJECT_DATA.SOLUTION_TYPE as SOLUTION_TYPE,
PROJECT_DATA.INTEGRATION_METHOD as INTEGRATION_METHOD,
PROJECT_MILESTONE.MILESTONE as MILESTONE,
PROJECT_MILESTONE.COMPLETED_ON as COMPLETED_ON,
PROJECT_MILESTONE.NOTES as NOTES
from PROJECT_DATA JOIN PROJECT_MILESTONE PROJECT_MILESTONE ON PROJECT_DATA.ID=PROJECT_MILESTONE.PROJECT_ID
where PROJECT_MILESTONE.COMPLETED_ON = (Select MAX (PROJECT_MILESTONE.COMPLETED_ON)
FROM PROJECT_MILESTONE
WHERE PROJECT_DATA.ID=PROJECT_MILESTONE.PROJECT_ID)
Any help on how to limit the query result to just 1 (newest one) when logged in the same date, will be extremely helpful.
Assuming that Completed on has the time as well along with the date, all you need to do is select top 1 in the ORDER BY DESC
Something like
select top 1 PROJECT_DATA.PARTNER_NAME as PARTNER_NAME,
PROJECT_DATA.SOLUTION_STATUS as SOLUTION_STATUS,
PROJECT_DATA.STRATEGY_MANAGER as STRATEGY_MANAGER,
PROJECT_DATA.SOLUTION_TYPE as SOLUTION_TYPE,
PROJECT_DATA.INTEGRATION_METHOD as INTEGRATION_METHOD,
PROJECT_MILESTONE.MILESTONE as MILESTONE,
PROJECT_MILESTONE.COMPLETED_ON as COMPLETED_ON,
PROJECT_MILESTONE.NOTES as NOTES
from PROJECT_DATA JOIN PROJECT_MILESTONE PROJECT_MILESTONE ON
PROJECT_DATA.ID = PROJECT_MILESTONE.PROJECT_ID
order by COMPLETED_ON DESC
Also, the joining condition has to be specified after the "ON" in joins and then you can use where condition to filter out the data
I've never been able to get my head around INNER JOINs (or any other JOIN types for that matter) so I'm struggling to work out how to use it in my specific situation. In fact, I'm not even sure if it's what I need. I've looked at other examples and read tutorials but my brain just doesn't seem to work the way needed to truly get it (or it doesn't function at all).
Here's the scenario:
I have two tables -
phone_numbers - this table has a list of phone numbers that
belong to lots of different customers. A single customer can have
multiple numbers. For simplicity's sake, we'll say the fields are
'number_id', 'customer_id', 'phone_number'.
call_history - this table has a record of every single call that one of these
numbers in the first table could have had. There's a record for
every individual call going back years. Again, for simplicity,
we'll say the relevant fields are customer_id, phone_number,
call_start_time.
What I'm trying to accomplish is to find all of the numbers that belong to a particular customer_id in the phone numbers table and use that information to search through the call_history table and find the number of calls each phone number has received, and group that by the number of calls for each number, preferably also showing zeros where a number hasn't received any calls at all.
The reason the zero calls is important is because that's the data I'm interested in. Otherwise, I could just get all the information out of the call_history table. But what I'm trying to achieve is find the numbers with no activity.
All I've been able to accomplish is run one query to get all of the numbers belonging to one customer:
SELECT customer_id, phone_number FROM phone_numbers WHERE customer_id = Y;
Then run a second query to get all phone calls for that customer_id for a set duration:
SELECT customer_id, phone_number, COUNT(*) FROM call_history WHERE customer_id = Y and call_start_time >= DATE_SUB(SYSDATE(), INTERVAL 30 DAY) GROUP BY phone_number;
I've then had to use the data returned from both queries and use a VLOOKUP function in Excel to match number of calls for each individual number from the second query to the list of all numbers from the first query, thus leaving blanks in my "all numbers" table and identifying those numbers that had no calls for that time period.
I'm hoping there's some way to do all of this with a single query and return a table of results, listing the zero number of calls with it and eliminate the whole manual Excel bit as it's not overly efficient and prone to human error.
Without at least a workable example from you, it's not easy to re-create your situation. Anyway, INNER JOIN might not return the result as how you expected. In my short time with MySQL, I mainly use 2 types of JOIN; one is already mentioned and the other is LEFT JOIN. From what I can understand in your question, what you want to achieve can be done by using LEFT JOIN instead of INNER JOIN. I may not be the best person to explain this to you but this is how I understand it:
INNER JOIN - only return anything that match in ON clause between two (or more) tables.
LEFT JOIN - will return everything from the table on the left side of the join and return NULL if ON get no match in the table on the right side of the join .. unless you specify some WHERE condition from something on the right table.
Now, here is my query suggestion and hopefully it'll be useful for you:
SELECT A.customer_id, A.phone_number,
SUM(CASE WHEN call_start_time >= DATE_SUB(SYSDATE(), INTERVAL 30 DAY)
THEN 1 ELSE 0 END) AS Total
FROM phone_numbers A
LEFT JOIN call_history B
ON A.customer_id=B.customer_id
GROUP BY A.customer_id,A.phone_number;
What I did here is I LEFT JOIN phone_numbers table with call_history on customer_id and I re-position the WHERE call_start_time >= .. condition into a CASE expression in the SELECT since putting it at WHERE will turn this into a normal join or inner join instead.
Here is an example fiddle : https://www.db-fiddle.com/f/hriFWqVy5RGbnsdj8i3aVG/1
For Inner join You should have to do like this way..
SELECT customer_id,phone_number FROM phone_numbers as pn,call_history as ch where pn.customer_id = ch.customer_id and call_start_time >= DATE_SUB(SYSDATE(), INTERVAL 30 DAY) GROUP BY phone_number;
Just add table name whatever you want to join and add condition
I have a table that contains a set of options and relevant pricing. We have versioning implemented which means that we store several rows for the same option with different timestamps. Everytime we make an update to the pricing, a new row is created with a timestamp.
I am using the query below:
SELECT
localizedOptionID,
uProfileID,
sOptionID,
MAX(datestamp),
localOptionName,
quantities
FROM
localisedProductOptions
WHERE
uProfileID = 2
AND sOptionID in ('BGCD','Q6G1','3BET')
GROUP BY sOptionID
ORDER BY MAX(datestamp)
It seems to be returning only one version of each row, but unfortunately it does not seem to be the latest.
Can anyone help me setting up the query? All the data is contained within one single table, so I am not using any join.
You can try the below mentioned query to get desire data
select localizedOptionID, uProfileID,sOptionID, datestamp,localOptionName,
quantities from localisedProductOptions WHERE uProfileID = 2 AND sOptionID in
('BGCD','Q6G1','3BET') and datestamp in(select MAX(datestamp) from
localisedProductOptions where uProfileID = 2 AND sOptionID in
('BGCD','Q6G1','3BET') GROUP BY sOptionID);
I have a Database with the following structure:
http://i.imgur.com/DFZz3Py.png
I'm trying to run a select statement, getting information from multiple tables, however it keeps bringing me duplicate results. The statement I'm using is:
SELECT StockReceipts.StockID, StockReceipts.Quantity, StockPriceHistory.Price
FROM StockReceipts,StockPriceHistory,Receipts
WHERE (Receipts.ReceiptID = 1) AND (Receipts.OrderDate BETWEEN StockPriceHistory.DateStart AND StockPriceHistory.DateEnd)
And the results i'm getting are:
http://i.imgur.com/2ZrgYyZ.png
What I actually want is matching rows from the stockreceipts table,
but with the price for each item of stock (the price that was within the date & time of ordering - OrderDate taken from the Receipts table) as well, taken from the StockPriceHistory table. I don't understand why it's making up duplicate/incorrect rows when there are only two rows in the StockReceipts table for that receipt.
Can anyone help? Thanks
SELECT
SR.StockID,
SR.Quantity,
SPH.Price
FROM
Receipts R
JOIN StockReceipts SR
on R.ReceiptID = SR.ReceiptID
JOIN StockPriceHistory SPH
on SR.StockID = SPH.StockID
WHERE
R.ReceiptID = 1
AND R.OrderDate BETWEEN SPH.DateStart AND SPH.DateEnd
You had no JOIN conditions between the tables leaving it a Cartesian result... For every record in one, grabbed entries from all other table rows.
I have two DB tables, one that store events and the second that stores any associated comments for that event.
DB Tables:
events: id, owner_id, timestamp
comments: cmt_id, parent_id(events id), cmt_time
I'm trying to get the last 5 comments for each event based on a specific owner_id.
This is how I'm joining my tables:
SELECT * FROM `events`
LEFT JOIN comments ON comments.parent_id=events.id
WHERE owner_id=X
ORDER BY timestamp DESC LIMIT 0,5
Any idea how I can get the number of comments based on the event_id?
Your question is about the number of comments for each event (at least as I interpret it). For this, you want to use a group by:
SELECT e.event_id, COUNT(c.parent_id) as NumComments
FROM events e left JOIN
comments c
ON c.parent_id=e.id
WHERE e.owner_id = X
group by e.event_id;
As for the query in your question. It does not do what you want it to do ("I'm trying to get the last 5 comments for each event based on a specific owner_id."). Instead, it is getting the last five comments for a given user. Period.
You can do the table join at then use the COUNT() function to count how many comments are associated with a given event_id
http://www.w3schools.com/sql/sql_func_count.asp
I would give an example but I'm not entirely sure what you would like your end dataset to look like. COUNT(col) will count the number of rows associated with the query result