How do I perform this ActiveRecord query?

Let’s learn how do I perform this ActiveRecord query. The most accurate or helpful solution is served by Stack Overflow.

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How to write this query with ActiveRecord or Mongoid?

Both of the interfaces for Mongoid and ActiveRecord are similar enough so I think either or will work. I need a query to meet the following criteria. I need to know the number of days a particular type of cereal has been eaten in the last 10 days. The cereal can be eaten 10 times in one day, but I only need to know that the day has had at least 1 time that the cereal was eaten. So if today is 11th, and a user has eaten Fruity Pebbles 2 times on the 5th, 10 times on the 7th, and once on the 8th...

Answer:

Not sure I understood. Cereal.where(:last_eaten.gt => Date.today - 10.day) or something like that...

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Other solutions

How can a T+n query perform a real-time, all-data query of a large amount of historical data stored in a transaction database?

Real-time all-data query of huge historical data stored in transaction database will create heavy workload to database and heavily destroy the necessary low-latency of transaction system. Separating historical data from database to ensure the performance...

Answer:

Hello. I'll address your question as two separate but related ones: How can I organize my transactional...

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Yuval Oren at Quora Mark as irrelevant Undo

How do you perform basic arithmetic in a MongoDB query?

In SQL, you can select many fields and perform basic arithmetic on them, by creating a query such as "SELECT ((field1 + field2)/2) as relevance, title, author from..."

Answer:

It's very easy: just download SlamData, an open source project that lets you run SQL on MongoDB, and...

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John A. De Goes at Quora Mark as irrelevant Undo

Can we perform a large number of Point Update Query in less than Amortized (logn) time?

If we have to perform range update query many times, Can we reduce the overall time? Edit - Can this be solved by applying DP or Hashing with BIT?

Answer:

Yes, it is possible in a special case. If all updates occur before queries, then updating the closed...

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Rajkiran Rajkumar at Quora Mark as irrelevant Undo

Create a field in sql query results?

i have two columns in a sql table that i need to perform math on (qty max - min onhand) during a query and display the calculated results in a field with the query results. i am using microsoft sql server management studio express to complete this. I...

Answer:

SELECT ... qty_max - min_onhand AS MyField ...

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Kevin K at Yahoo! Answers Mark as irrelevant Undo

MS SQL query causes vague error message?

I am converting an ASP script to a PHP script. The current script runs on an IIS 6.0 server running ASP.NET and PHP 4.4.8. The script connects to a database in the form of a .MDB file. I can successfully connect to the database using the PHP method odbc...

Answer:

"Name" is a restricted word in Microsoft Access and SQL Server. Try changing your query to...

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William B at Yahoo! Answers Mark as irrelevant Undo

Can you prevent developers from using raw SQL queries in ActiveRecord?

We are running a rails+mysql application. In my specific requirement I want all my developers to access mysql only throught the rails API. I want to disable all direct mysql queries outside rails.  I need this because I have a lot of callbacks running...

Answer:

Just ask your developers not to write and run SQL queries directly on the connection object, and to...

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James Stradling at Quora Mark as irrelevant Undo

How many processors does a Google search query touch?

When I enter a search query on Google (without Google Instant), how many processors (in the median case) perform work for this query? How about the extreme case, and if Google Instant is on as well?

Answer:

A single Google search engine query uses 1,000 servers in 0.2 seconds.   Sources: http://www.computerweekly...

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Wolf Garbe at Quora Mark as irrelevant Undo

Access Database Sort/Query...Please Answer?

Can you give me a reason for each of the following please?:) 1) Why is is a good idea to perform a 'sort'? 2) Why is it a good idea to perform a 'query'? Thanks x

Answer:

sort is used for sorting the data in ascending or descending order. if a customer is using your website...

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Lala Lottexx at Yahoo! Answers Mark as irrelevant Undo

Advanced range query in mongodb?

There are two fields in one collection "max" and "min". I have two integers X and y. I want to perform a query like this on the collection; find all the rows whose 'min'-y <= X <='max'+y. How can i do that [updated] in pymongo...

Answer:

It is possible to pass the exact query( 'min'-y <= X <='max'+y) in javascript as suggested by...

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Answer Wiki at Quora Mark as irrelevant Undo

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