Outer Join And Distinct
I just started building a website and use MySQL as my backend database. I'm having a little trouble creating an SQL query that will get the correct information out.
Here's my problem:
I have 3 tables:
people: stores the name of people who can vote
votetype: stores the type of votes there are (In favor, Against, Withheld)
decisions: the dicisions that were voted on
Then I have another table that links them all together called votes. Votes has three columns: personID, typeID and decisionID. personID and decisionID are primary key. All are foreign key to obvious tables.
I want to retrieve for a given person the votes he made for all decisions. So: a list of all decisions with the vote he or she made and a NULL if there is no vote.
So far I have this query:
SELECT DISTINCT d.ID, d.name, d.date, v.typeID AS vID, t.name FROM decisions d, votetype t LEFT OUTER JOIN votes v ON v.decisionID = d.ID WHERE (v.personID=1 OR v.personID IS NULL) AND (v.typeID=t.ID OR v.typeID IS NULL) ORDER BY d.date;
For some reason the DISTINCT doesn't work and I get a decision that is not voted for three times (once for each type while v.typeID column is NULL).
How can I fix this so each decision only shows up once?
Jurgen
-------------------------
I've found a solution:
SELECT DISTINCT d.ID, d.name, d.date, v.typeID AS vID, IF(v.typeID IS NULL,NULL,t.name) AS stem FROM decision d, votetype t LEFT OUTER JOIN votes v ON v.decisionID = d.ID WHERE (v.personID=1 OR v.personID IS NULL) AND (v.typeID=t.ID OR v.typeID IS NULL) ORDER BY d.date;
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Select d.* from ( select agent_addr, max(date_time) from eventlog where priority = 1 group by agent_addr) d, (select agent_addr, max(date_time) from eventlog where priority = 6 group by agent_addr) u where d.agent_addr = u.agent_addr and d.access_time >= u.access_time The above statement is to get certain data from an event table. I need all of the lines where the event is 1 and there are no newer event 1's or event 6's I need to know what devices are currently down (Priority 1) based on this history table. where there is no newer event 1 entries for the agent_addr, or there is no newer priority 6's for that agent_addr (priority 6 means device is back up) I'm stumped on the syntax to do joins, or to get this to work. the table works like the following device goes down entry is made as priority 1 eventid 1 device comes back up new endtry is made priority 6 eventid 2 device goes back down another entry is made as priority 1. eventid 3 I need to make sure i only am getting a list of the latest status of each device in the aformentioned scenario it would be the one with event ID 3
LEFT JOIN? RIGHT JOIN? Multiple JOIN?
Simplifying this down to its basics, I'm using LEFT JOIN in a query but I'm not getting the results I want. The tables are: table services service_id service_name table services_provided service_id service_date (date field) cust_id service_quantity I need to select ALL services from the services table, and the number of services provided (by a specific customer, in a specific time frame) from the services_provided table, so that I can generate a list that shows services provided by that customer in the specified period of time The query: SELECT service_date, service_name, service_quantity FROM services LEFT JOIN services_provided ON services_provided.service_id = services.service_id WHERE cust_id = $cust_id AND MONTH(service_date) = 10 AND YEAR(service_date) = 2007 GROUP BY service_id ORDER BY service_id (Aside: The date to be selected varies - it may be the whole year, or may be a selection of months,such as 1, 2 or 3. This is determined dynamically in the script. The cust_id is determined by which customer is logged in.) I'm pretty sure that the left join as I have it should return all services, even if there's no corresponding entry in the services_provided table. But because of the WHERE clause, I don't get a complete list of all services -- if the customer doesn't have any entries for a particular service, that service doesn't come up in my results. Do I need to change how I'm joining the tables, or join them twice? I'm sure I could do this with a nested query, but I'm trying to avoid that.
Join Vs. Inner Join Vs. Implied Join = Different Results ??
I SUM() only on the order table in all queries below. Here's a set of queries that I thought would/should yield the exact same results: QUERY 1: SELECT COUNT( o.orderID ) FROM order o WHERE DATE( o.orderDATE ) = ��-01-04' AND o.orderSTATUS = 300 yields 161 QUERY 2: SELECT COUNT( o.orderID ) FROM order o LEFT OUTER JOIN credit_card cc ON o.orderID = cc.orderID WHERE DATE( o.orderDATE ) = ��-01-04' AND o.orderSTATUS = 300 yields 175 QUERY 3: SELECT COUNT( o.orderID ) FROM order o, credit_card cc WHERE o.orderID = cc.orderID AND DATE( o.orderDATE ) = ��-01-04' AND o.orderSTATUS = 300 yields 157
Connecting Three Tables With Left Join And Ordinary Join
I have 3 Mysql tables: Week (with columns day and hour) Activity (with columns day, hour, activityid and ac_text) Person (with columns name and activityid) I would like to create a scheme showing the activities during a week sorted on days and hours. If I ignore the person table I can fix it with the statement: Select …. From week left join activity on (week.day = activity.day) and (week.hour = activity.hour) order by day, hour I can then make a loop (I am usin asp.net) that writes the activities. My problem is when I try to combine the persons to the activtities in an given hour. How do I do that ? (activity.activityid = person.activityid). I have a little extra question. When I make the join above and print the result (day, time and activity) there isn’t any output if no activity matches a given day and hour. How do I do when I always want to print day and hour and add activity where such exist.
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