gql

问题 I don't know if this has been asked here. I saw couple of questions on "like" operator but I'm not sure if that's I'm looking for. Sorry I'm a noob at this. But I am moving from MySQL to Google App Engine and was wondering if there was an OR operator in GQL similar to ones in MySQL. Basically what I am trying to achieve is get the login on name via their username or email address. So my query would be something like this. query = db.GqlQuery("SELECT * FROM mytable where username = :name OR

问题 I have a google database called Main . class Main(db.Model): name = db.StringProperty() phone = db.StringProperty() There's another database Photo which references Main through a one-to-many relationship. class Photo(db.Model): main = db.ReferenceProperty(Main,collection_name='photos') photo1 = db.StringProperty() photo2 = db.StringProperty() I was wondering if anyone knows how to make a dictionary, based on the query of Main (example shown below): class Name(webapp.RequestHandler): def get

问题 In the interest of time, I do mean GQL, as in SELECT * FROM Song WHERE composer = 'Lennon, John' The following failed SELECT COUNT(*) FROM myEntity also the following SELECT COUNT() FROM myEntity 回答1: As shown here, there is actually a way to count the return of your GQL. The doc about the GQL language shows you can't really do a count on the query itself. So what you would do is take your select *, put it in a GQL query object, then call the "count()" method on that object to have the count

问题 My sql looks like this : SELECT * FROM Contact_Info_Entry where Name.length < 18 [ Got incorrect GQL syntax error message ] "Name" is a String in the Contact_Info_Entry.java class, I'm not familiar with sql, let alone GQL, if I want to select all names less than 18 characters long, what's the correct GQL syntax to use ? 回答1: You can't filter by a field's length with GQL. However, you could achieve this if you denormalize your model and include the length of Name as a field in your model. 回答2:

问题 Having some issues with merging two GQLQueries in GAE (python). fp_events = db.GqlQuery("SELECT * FROM Event WHERE firstPlayer=:1", alias).fetch(mylimit) sp_events = db.GqlQuery("SELECT * FROM Event WHERE secondPlayer=:1", alias).fetch(mylimit) events = fp_events.append(sp_events) However, when I try to iterate through these events using the for loop for event in events: , I get a TypeError: 'NoneType' object is not iterable error at that line. I suspect that this has something to do with the

问题 I have some entities that have a StringProperty and I would like to query for all the entities that match a substring. Is there a way to do that using just GQL? For example, if my datastore looks like this: ID/Name question_text -------------------------------------------------------------- 3001 I like to eat chicken. 3020 I only like to eat chicken that is deep fried. 3045 I like filet mignon. 3052 I like cheese. What would the GQL query be to find all the entities that contain 'chicken' in

问题 I'm trying to apply cursor to my app, however, the document is not clear enough for me. Google's description for cursor http://code.google.com/appengine/docs/python/datastore/queries.html#Query_Cursors The cursor's position is defined as the location in the result list after the last result returned. A cursor is not a relative position in the list (it's not an offset); it's a marker to which the datastore can jump when starting an index scan for results. If the results for a query change

问题 Is it possible to INSERT or UPDATE a entity in the datastore using the Admin > Datastore Viewer. E.g. executing something like INSERT INTO table VALUES (Foo='Bar') 回答1: No you can't; GQL is a SQL-like language just for retrieving entities or keys. You can INSERT, UPDATE or DELETE entities using the Datastore Viewer or from your application code. 回答2: Not with GQL, but it is possible to INSERT and UPDATE entities with the Datastore Viewer . To INSERT : After clicking on the Datastore Viewer ,

问题 I would think this would be easy for an SQL-alike! What I want is the GQL equivalent of: select count(*) from foo; and to get back an answer something similar to: 1972 records. And I want to do this in GQL from the "command line" in the web-based DataStore viewer. (You know, the one that shows 20 at a time and lets me see "next 20") Anyway -- I'm sure it's brain-dead easy, I just can't seem to find the correct syntax. Any help would be appreciated. Thanks! 回答1: As it's stated in other

问题 I have a following model in the Google appengine app. class TestModel(db.Model): names = db.StringListProperty(required=False) So, I want to get entries which has not empty in names property. I tried like this. TestModel.all().filter('names !=', []) But it raises the exception: BadValueError: Filtering on lists is not supported How can I filter it? or Should I check one by one like following? for entry in TestModel.all(): if len(entry.names) > 0: result.append(entry) 回答1: Try this: TestModel