aggregate

问题 I want to create a pivot table view showing month on month sum of bookings for every travel_mode . Table bookings : timestamp , bookings , provider_id Table providers : provider_id , travel_mode Pivot table function and crosstab functions are not to be used to do this. So I am trying to use JOIN and CASE. Following is the query: SELECT b.month, (CASE WHEN p.travel_mode=train then b.amount end)train, (CASE WHEN p.travel_mode=bus then b.amount end)bus, (CASE WHEN p.travel_mode=air then b.amount

问题 This question already has answers here : Aggregate / summarize multiple variables per group (e.g. sum, mean) (6 answers) Closed 2 years ago . From a data frame of many columns, I would like to aggregate (i.e. sum ) hundreds of columns by a single column, without specifying each of the column names. Some sample data: names <- floor(runif(20, 1, 5)) sample <- cbind(names) for(i in 1:20){ col <- rnorm(20,2,4) sample <- cbind(sample, col) } What I have until now is the following code, but it

问题 The application Im working on needs to enforce the following rules (among others): We cannot register a new user to the system if the active user quota for the tenant is exceeded. We cannot make a new project if the project quota for the tenant is exceeded. We cannot add more multimedia resources to any project that belongs to a tenant if the maximum storage quota defined in the tenant is exceeded The main entities involved in this domain are: Tenant Project User Resource As you can imagine,

问题 I have this nested Schema for my courses collections, there is a sessions array in every course and a students array in every session and every student is an object consisting of a property of userName with a value of ObjectId refering to my users collections and another property names status containing some number. I want to delete an student object from my students array of my session with its _id. I know it is possible to unwind arrray to get to a single object but I need a neat way like

问题 Lets say I have a few of tables orders = Arel::Table.new :orders stores = Arel::Table.new :stores managers = Arel::Table.new :managers And a manager has many stores and a store has many orders. One day I want to query for the average total across orders where a manager works. Oh, I want to group that by the store. So to be clear, I want to get the average order total for a manager, for each of the stores they work at. And let's assume we've looked up our manager: manager = Manager.find(some

问题 Lets say I have a few of tables orders = Arel::Table.new :orders stores = Arel::Table.new :stores managers = Arel::Table.new :managers And a manager has many stores and a store has many orders. One day I want to query for the average total across orders where a manager works. Oh, I want to group that by the store. So to be clear, I want to get the average order total for a manager, for each of the stores they work at. And let's assume we've looked up our manager: manager = Manager.find(some

问题 My documents in the orders collection has _client key, which is an ObjectId references to another entity in another collection. The collection could be organization and could be users - I mean - it's variable collection. I want to tell Mongo to lookup if the _client id is found in both collections. { $lookup: { from: "users", // could be "organizations" let: { "client": "$_client" }, // could be "_organization" pipeline: [ { $match: { $expr: { $eq: ["$_id", "$$client"] }}}, ], as: "client" }

问题 aggregrated_table = df_input.groupBy('city', 'income_bracket') \ .agg( count('suburb').alias('suburb'), sum('population').alias('population'), sum('gross_income').alias('gross_income'), sum('no_households').alias('no_households')) Would like to group by city and income bracket but within each city certain suburbs have different income brackets. How do I group by the most frequently occurring income bracket per city? for example: city1 suburb1 income_bracket_10 city1 suburb1 income_bracket_10

问题 Since all entities have a stamped of who created/modified the record, can we consider a Person entity an aggregate root to all entities? That is, all entities that references the Person will become a collection to Person, e.g. public class Person { public virtual int PersonId { get; set; } public virtual string Lastname { get; set; } public virtual IList<OrderHeader> CreatedOrders { get; set; } public virtual IList<OrderHeader> ModifiedOrders { get; set; } // Other entities that have a

问题 I am researching creating multi-output devices on either OS X or iOS, and I found out that CoreAudio would allow you to create aggregate devices. My first question is, does iOS allow you to do this. I know that this is certainly possible on OS X, but I've heard that iOS will not allow it. I would really appreciate an example of how you would go about detecting multiple audio output devices and creating an aggregate device, all using swift. I have checked here, but it doesn't fully answer my