I'm usually a PHP programmer, but I'm currently working on a project in MS Access 2003 and I'm a complete VBA newbie. I'm trying to do something that I could easily do in PHP but I have no idea how to do it in Access. The facts are as follows:
Tables and relevant fields:
tblItems: item_id, on_hand
tblProjects: project_id
tblProjectItems: project_id, item_id
Goal: Determine which projects I could potentially do, given the items on-hand.
I need to find a way to compare each project's required items against the items on-hand to determine if there are any items missing. If not, add the project to the list of potential projects. In PHP I would compare an array of on-hand items with an array of project items required, using the array_diff function; if no difference, add project_id to an array of potential projects.
For example, if...
$arrItemsOnHand = 1,3,4,5,6,8,10,11,15
$arrProjects[1] = 1,10
$arrProjects[2] = 8,9,12
$arrProjects[3] = 7,13
$arrProjects[4] = 1,3
$arrProjects[5] = 2,14
$arrProjects[6] = 2,5,8,10,11,15
$arrProjects[7] = 2,4,5,6,8,10,11,15
...the result should be:
$arrPotentialProjects = 1,4
Is there any way to do this in Access?
Consider a single query to reach your goal: "Determine which projects I could potentially do, given the items on-hand."
SELECT
pi.project_id,
Count(pi.item_id) AS NumberOfItems,
Sum(IIf(i.on_hand='yes', 1, 0)) AS NumberOnHand
FROM
tblProjectItems AS pi
INNER JOIN tblItems AS i
ON pi.item_id = i.item_id
GROUP BY pi.project_id
HAVING Count(pi.item_id) = Sum(IIf(i.on_hand='yes', 1, 0));
That query computes the number of required items for each project and the number of those items which are on hand.
When those two numbers don't match, that means at least one of the required items for that project is not on hand.
So the HAVING clause excludes those rows from the query result set, leaving only rows where the two numbers match --- those are the projects for which all required items are on hand.
I realize my description was not great. (Sorry.) I think it should make more sense if you run the query both with and without the HAVING clause ... and then read the description again.
Anyhow, if that query gives you what you need, I don't think you need VBA array handling for this. And if you can use that query as your form's RecordSource or as the RowSource for a list or combo box, you may not need VBA at all.
Related
I could need some help with a Anylogic Model.
Model (short): Manufacturing scenario with orders move in a individual route. The workplaces (WP) are dynamical created by simulation start. Their names, quantity and other parameters are stored in a database (excel Import). Also the orders are created according to an import. The Agent population "order" has a collection routing which contains the Workplaces it has to stop in the specific order.
Target: I want a moveTo block in main which finds the next destination of the agent order.
Problem and solution paths:
I set the destination Type to agent and in the Agent field I typed a function agent.getDestination(). This function is in order which returns the next entry of the collection WP destinationName = routing.get(i). With this I get a Datatype error (while run not compiling). I quess it's because the database does not save the entrys as WP Type but only String.
Is there a possiblity to create a collection with agents from an Excel?
After this I tried to use the same getDestination as String an so find via findFirst the WP matching the returned name and return it as WP. WP targetWP = findFirst(wps, w->w.name == destinationName);
Of corse wps (the population of Workplaces) couldn't be found.
How can I search the population?
Maybe with an Agentlink?
I think it is not that difficult but can't find an answer or a solution. As you can tell I'm a beginner... Hope the description is good an someone can help me or give me a hint :)
Thanks
Is there a possiblity to create a collection with agents from an Excel?
Not directly using the collection's properties and, as you've seen, you can't have database (DB) column types which are agent types.1
But this is relatively simple to do directly via Java code (and you can use the Insert Database Query wizard to construct the skeleton code for you).
After this I tried to use the same getDestination as String an so find via findFirst the WP matching the returned name and return it as WP
Yes, this is one approach. If your order details are in Excel/the database, they are presumably referring to workplaces via some String ID (which will be a parameter of the workplace agents you've created from a separate Excel worksheet/database table). You need to use the Java equals method to compare strings though, not == (which is for comparing numbers or whether two objects are the same object).
I want a moveTo block in main which finds the next destination of the agent order
So the general overall solution is
Create a population of Workplace agents (let's say called workplaces in Main) from the DB, each with a String parameter id or similar mapped from a DB column.
Create a population of Order agents (let's say called orders in Main) from the DB and then, in their on-startup action, set up their collection of workplace IDs (type ArrayList, element class String; let's say called workplaceIDsList) using data from another DB table.
Order probably also needs a working variable storing the next index in the list that it needs to go to (so let's say an int variable nextWorkplaceIndex which starts at 0).
Write a function in Main called getWorkplaceByID that has a single String argument id and returns a Workplace. This gets the workplace from the population that matches the ID; a one-line way similar to yours is findFirst(workplaces, w -> w.id.equals(id)).
The MoveTo block (which I presume is in Main) needs to move the Order to an agent defined by getWorkplaceByID(agent.workplaceIDsList.get(nextWorkplaceIndex++)). (The ++ bit increments the index after evaluating the expression so it is ready for the next workplace to go to.)
For populating the collection, you'd have two tables, something like the below (assuming using strings as IDs for workplaces and orders):
orders table: columns for parameters of your orders (including some String id column) other than the workplace-list. (Create one Order agent per row.)
order_workplaces table: columns order_id, sequence_num and workplace_id (so with multiple rows specifying the sequence of workplace IDs for an order ID).
In the On startup action of Order, set up the skeleton query code via the Insert Database Query wizard as below (where we want to loop through all rows for this order's ID and do something --- we'll change the skeleton code to add entries to the collection instead of just printing stuff via traceln like the skeleton code does).
Then we edit the skeleton code to look like the below. (Note we add an orderBy clause to the initial query so we ensure we get the rows in ascending sequence number order.)
List<Tuple> rows = selectFrom(order_workplaces)
.where(order_workplaces.order_id.eq(id))
.orderBy(order_workplaces.sequence_num.asc())
.list();
for (Tuple row : rows) {
workplaceIDsList.add(row.get(order_workplaces.workplace_id));
}
1 The AnyLogic database is a normal relational database --- HSQLDB in fact --- and databases only understand their own specific data types like VARCHAR, with AnyLogic and the libraries it uses translating these to Java types like String. In the user interface, AnyLogic makes it look like you set the column types as int, String, etc. but these are really the Java types that the columns' contents will ultimately be translated into.
AnyLogic does support columns which have option list types (and the special Code type column for columns containing executable Java code) but these are special cases using special logic under the covers to translate the column data (which is ultimately still a string of characters) into the appropriate option list instance or (for Code columns) into compiled-on-the-fly-and-then-executed Java).
Welcome to Stack Overflow :) To create a Population via Excel Import you have to create a method and call Code like this. You also need an empty Population.
int n = excelFile.getLastRowNum(YOUR_SHEET_NAME);
for(int i = FIRST_ROW; i <= n; i++){
String name = excelFile.getCellStringValue(YOUR_SHEET_NAME, i, 1);
double SEC_PARAMETER_TO_READ= excelFile.getCellNumericValue(YOUR_SHEET_NAME, i, 2);
WP workplace = add_wps(name, SEC_PARAMETER_TO_READ);
}
Now if you want to get a workplace by name, you have to create a method similar to your try.
Functionbody:
WP workplaceToFind = wps.findFirst(w -> w.name.equals(destinationName));
if(workplaceToFind != null){
//do what ever you want
}
and thanks in advance for any and all help!!
I'm running a query on the datastore that looks like this:
forks = Thing.query(ancestor=user.subscriber_key).filter(
Thing.status==True,
Thing.fork_of==thing_key,
Thing.start_date <= user.day_threshold(),
Thing.level.IN([1,2,3,4,5])).order(
Thing.level)
This query works and returns the results I expect. However, I would like to sort it on one additional field (Thing.last_touched). If I add this to the sort, it won't work because Thing.last_touched is not the property to which the inequality filter is applied. I can't add an additional inequality filter, since we're only allowed one, plus it's not needed (actually, that's why Thing.leve.IN is there.. not needed as a filter, but required for the sort).
So, what I'm wondering is, could I run the query with the filters that I want, and then run code to sort the query results myself? I know I could pull all the parameters I want to sort and store them in dictionaries and sort them that way, but it seems to me there ought to be a way to handle this with the query.
I've searched for days for this but have had no luck.
Just in case you need it, here's the class definition of Thing:
class Thing(ndb.Model):
title = ndb.StringProperty()
level = ndb.IntegerProperty()
fork = ndb.BooleanProperty()
recursion_level = ndb.IntegerProperty()
fork_of = ndb.KeyProperty()
creation_date = ndb.DateTimeProperty(auto_now_add=True)
last_touched = ndb.DateTimeProperty(auto_now=True)
status = ndb.BooleanProperty()
description = ndb.StringProperty()
owner_id = ndb.StringProperty()
frequency = ndb.IntegerProperty()
start_date = ndb.DateTimeProperty(auto_now_add=True)
due_date = ndb.DateTimeProperty()
One of the main reasons that Google AppEngine is so fast even when dealing with insane amounts of data is because of the very limited query options. All standard queries are "scans" over an index, i.e. there is some table (index) that keeps references to your actual data entires in order sorted by ONE of the data's properties. So, let's say you add the following entries:
Thing A: start-date = Wednesday (I'm just going to use weekdays for simplicity)
Thing B: start-date = Friday
Thing C: start-date = Monday
Thing D: start-date = Thursday
Then, AppEngine will create an index that looks like this:
1 - Monday -> Thing C
2 - Wednesday -> Thing A
3 - Thursday -> Thing D
4 - Friday -> Thing B
Now, any query will correspond to a continuous block in this (or another) index. If you, for example, say "All Things with start-date >= Tuesday", it will return entries in row 2 through 4 (i.e. Thing A, Thing D, and Thing B in that exact order!). If you query for "< Thursday", you get 1-2. If you say "> Tuesday and <= Thursday" you get 2-3.
And if you are doing inequality filters on a different property, AppEngine will use a different index.
This is why you can only do one inequality filter and why the sort-order is always also specified by the property that you do an inequality filter of. Because AppEngine is not designed to be able to return items 1, 2, 4 (with a gap*) out of an index, or items 4, 2, 3 (no gap, but out of order).
So, if you need to sort your entries on a different property other than the one you use for inequality filtering, you basically have 3 choices:
Perform your query with the inequality filter, read all results into memory, and sort them in your code afterwards (I think this is what you mean by storing them in a dictionary)
Perform your query WITHOUT the inequality filter, but sorted on the right property. Then, as you loop over the returned entries, simply check the inequality yourself and drop the ones that don't match
Perform your query with the inequality filter and just return the items in the wrong order, and let the client-application worry about sorting them! ;)
Generally I would assume that you have much more unused resources available client-side to do the sorting, so I would probably go for option 3 in most cases. But if you need to sort the entries server-side (e.g. for a mobile-app targeted at older smart-phones), it will depend on the size of your database and the fraction of entries that usually match your inequality filter, whether option 1 or option 2 are better. If your inequality filter only removes a small fraction of the entries, option 2 might be much faster (as it doesn't require any O(>n) sorting), but if you have a huge database of entries and only a very small number of them will match the inequality, definitely go for option 1.
BTW: The talk "App Engine Datastore Under the Covers" from Google I/O 2008 might be a very helpful resource. It's a bit technical, but it gives a great overview of this topic and I consider it must-know information if you want to do anything in AppEngine. Note, though, that this talk is a bit out-dated. There are a bunch more things that you can do with queries now-a-days. But ALL of these extra things (if I understand correctly) are API functions that in the end just generate a set of several simple queries (exactly like the ones described in this talk) and then just combine the results of these in memory in your application (just like you would if you did your own sorting).
*There are some exceptions where AppEngine can generate the intersection of two (or more?) index-scans to drop items from the results, but I don't think that you could use that to change the order of the returned entries.
I am working currently on telecom analytics project and newbie in query optimisation. To show result in browser it takes a full minute while just 45,000 records are to be accessed. Could you please suggest on ways to reduce time for showing results.
I wrote following query to find call-duration of a person of age-group:
sigma=0
popn=len(Demo.objects.filter(age_group=age))
card_list=[Demo.objects.filter(age_group=age)[i].card_no
for i in range(popn)]
for card in card_list:
dic=Fact_table.objects.filter(card_no=card.aggregate(Sum('duration'))
sigma+=dic['duration__sum']
avgDur=sigma/popn
Above code is within for loop to iterate over age-groups.
Model is as follows:
class Demo(models.Model):
card_no=models.CharField(max_length=20,primary_key=True)
gender=models.IntegerField()
age=models.IntegerField()
age_group=models.IntegerField()
class Fact_table(models.Model):
pri_key=models.BigIntegerField(primary_key=True)
card_no=models.CharField(max_length=20)
duration=models.IntegerField()
time_8bit=models.CharField(max_length=8)
time_of_day=models.IntegerField()
isBusinessHr=models.IntegerField()
Day_of_week=models.IntegerField()
Day=models.IntegerField()
Thanks
Try that:
sigma=0
demo_by_age = Demo.objects.filter(age_group=age);
popn=demo_by_age.count() #One
card_list = demo_by_age.values_list('card_no', flat=True) # Two
dic = Fact_table.objects.filter(card_no__in=card_list).aggregate(Sum('duration') #Three
sigma = dic['duration__sum']
avgDur=sigma/popn
A statement like card_list=[Demo.objects.filter(age_group=age)[i].card_no for i in range(popn)] will generate popn seperate queries and database hits. The query in the for-loop will also hit the database popn times. As a general rule, you should try to minimize the amount of queries you use, and you should only select the records you need.
With a few adjustments to your code this can be done in just one query.
There's generally no need to manually specify a primary_key, and in all but some very specific cases it's even better not to define any. Django automatically adds an indexed, auto-incremental primary key field. If you need the card_no field as a unique field, and you need to find rows based on this field, use this:
class Demo(models.Model):
card_no = models.SlugField(max_length=20, unique=True)
...
SlugField automatically adds a database index to the column, essentially making selections by this field as fast as when it is a primary key. This still allows other ways to access the table, e.g. foreign keys (as I'll explain in my next point), to use the (slightly) faster integer field specified by Django, and will ease the use of the model in Django.
If you need to relate an object to an object in another table, use models.ForeignKey. Django gives you a whole set of new functionality that not only makes it easier to use the models, it also makes a lot of queries faster by using JOIN clauses in the SQL query. So for you example:
class Fact_table(models.Model):
card = models.ForeignKey(Demo, related_name='facts')
...
The related_name fields allows you to access all Fact_table objects related to a Demo instance by using instance.facts in Django. (See https://docs.djangoproject.com/en/dev/ref/models/fields/#module-django.db.models.fields.related)
With these two changes, your query (including the loop over the different age_groups) can be changed into a blazing-fast one-hit query giving you the average duration of calls made by each age_group:
age_groups = Demo.objects.values('age_group').annotate(duration_avg=Avg('facts__duration'))
for group in age_groups:
print "Age group: %s - Average duration: %s" % group['age_group'], group['duration_avg']
.values('age_group') selects just the age_group field from the Demo's database table. .annotate(duration_avg=Avg('facts__duration')) takes every unique result from values (thus each unique age_group), and for each unique result will fetch all Fact_table objects related to any Demo object within that age_group, and calculate the average of all the duration fields - all in a single query.
I'm using an MDX query to pull information to support a set of reports. A high degree of detail is required for the reports so they take some time to generate. To speed up the access time we pull the data we need and store it in a flat Oracle table and then connect to the table in Excel. This makes the reports refresh in seconds instead of minutes.
Previously the MDX was generated and run by department for 100 departments and then for a number of other filters. All this was done in VB.Net. The requirements for filters have grown to the point where this method is not sustainable (and probably isn't the best approach regardless).
I've built the entire dataset into one MDX query that works perfectly. One of my sets that I cross join includes members from three different levels of hierarchy, it looks like this:
(
Descendants([Merch].[Merch CHQ].[All], 2),
Descendants([Merch].[Merch CHQ].[All], 3),
[Merch].[Merch CHQ].[Department].&[1].Children
)
The problem for me is in our hierarchy (which I can't change), each group (first item) and each department (second item) have the same structure to their naming, ie 15-DeptName and it's confusing to work with.
To address it I added a member:
MEMBER
[Measures].[Merch Level] AS
(
[Merch].[Merch CHQ].CurrentMember.Level.Name
)
Which returns what type the member is and it works perfectly.
The problem is that it updates for every member so none of the rows get filtered by NON BLANK, instead of 65k rows I have 130k rows which will hurt my access performance.
Can my query be altered to still filter out the non blanks short of using IIF to check each measurement for null?
You can specify Null for your member based on your main measure like:
MEMBER
[Measures].[Merch Level] AS
IIf(IsEmpty([Measures].[Normal Measure]),null,[Merch].[Merch CHQ].CurrentMember.Level.Name)
That way it will only generate when there is data. You can go further and add additional dimensions to the empty check if you need to get more precise.
I'm writing an NHibernate criteria that selects data supporting paging. I'm using the COUNT(*) OVER() expression from SQL Server 2005(+) to get hold of the total number of available rows, as suggested by Ayende Rahien. I need that number to be able to calculate how many pages there are in total. The beauty of this solution is that I don't need to execute a second query to get hold of the row count.
However, I can't seem to manage to write a working criteria (Ayende only provides an HQL query).
Here's an SQL query that shows what I want and it works just fine. Note that I intentionally left out the actual paging logic to focus on the problem:
SELECT Items.*, COUNT(*) OVER() AS rowcount
FROM Items
Here's the HQL:
select
item, rowcount()
from
Item item
Note that the rowcount() function is registered in a custom NHibernate dialect and resolves to COUNT(*) OVER() in SQL.
A requirement is that the query is expressed using a criteria. Unfortunately, I don't know how to get it right:
var query = Session
.CreateCriteria<Item>("item")
.SetProjection(
Projections.SqlFunction("rowcount", NHibernateUtil.Int32));
Whenever I add a projection, NHibernate doesn't select item (like it would without a projection), just the rowcount() while I really need both. Also, I can't seem to project item as a whole, only it's properties and I really don't want to list all of them.
I hope someone has a solution to this. Thanks anyway.
I think it is not possible in Criteria, it has some limits.
You could get the id and load items in a subsequent query:
var query = Session
.CreateCriteria<Item>("item")
.SetProjection(Projections.ProjectionList()
.Add(Projections.SqlFunction("rowcount", NHibernateUtil.Int32))
.Add(Projections.Id()));
If you don't like it, use HQL, you can set the maximal number of results there too:
IList<Item> result = Session
.CreateQuery("select item, rowcount() from item where ..." )
.SetMaxResult(100)
.List<Item>();
Use CreateMultiCriteria.
You can execute 2 simple statements with only one hit to the DB that way.
I am wondering why using Criteria is a requirement. Can't you use session.CreateSQLQuery? If you really must do it in one query, I would have suggested pulling back the Item objects and the count, like:
select {item.*}, count(*) over()
from Item {item}
...this way you can get back Item objects from your query, along with the count. If you experience a problem with Hibernate's caching, you can also configure the query spaces (entity/table caches) associated with a native query so that stale query cache entries will be cleared automatically.
If I understand your question properly, I have a solution. I struggled quite a bit with this same problem.
Let me quickly describe the problem I had, to make sure we're on the same page. My problem came down to paging. I want to display 10 records in the UI, but I also want to know the total number of records that matched the filter criteria. I wanted to accomplish this using the NH criteria API, but when adding a projection for row count, my query no longer worked, and I wouldn't get any results (I don't remember the specific error, but it sounds like what you're getting).
Here's my solution (copy & paste from my current production code). Note that "SessionError" is the name of the business entity I'm retrieving paged data for, according to 3 filter criterion: IsDev, IsRead, and IsResolved.
ICriteria crit = CurrentSession.CreateCriteria(typeof (SessionError))
.Add(Restrictions.Eq("WebApp", this));
if (isDev.HasValue)
crit.Add(Restrictions.Eq("IsDev", isDev.Value));
if (isRead.HasValue)
crit.Add(Restrictions.Eq("IsRead", isRead.Value));
if (isResolved.HasValue)
crit.Add(Restrictions.Eq("IsResolved", isResolved.Value));
// Order by most recent
crit.AddOrder(Order.Desc("DateCreated"));
// Copy the ICriteria query to get a row count as well
ICriteria critCount = CriteriaTransformer.Clone(crit)
.SetProjection(Projections.RowCountInt64());
critCount.Orders.Clear();
// NOW add the paging vars to the original query
crit = crit
.SetMaxResults(pageSize)
.SetFirstResult(pageNum_oneBased * pageSize);
// Set up a multi criteria to get your data in a single trip to the database
IMultiCriteria multCrit = CurrentSession.CreateMultiCriteria()
.Add(crit)
.Add(critCount);
// Get the results
IList results = multCrit.List();
List<SessionError> sessionErrors = new List<SessionError>();
foreach (SessionError sessErr in ((IList)results[0]))
sessionErrors.Add(sessErr);
numResults = (long)((IList)results[1])[0];
So I create my base criteria, with optional restrictions. Then I CLONE it, and add a row count projection to the CLONED criteria. Note that I clone it before I add the paging restrictions. Then I set up an IMultiCriteria to contain the original and cloned ICriteria objects, and use the IMultiCriteria to execute both of them. Now I have my paged data from the original ICriteria (and I only dragged the data I need across the wire), and also a raw count of how many actual records matched my criteria (useful for display or creating paging links, or whatever). This strategy has worked well for me. I hope this is helpful.
I would suggest investigating custom result transformer by calling SetResultTransformer() on your session.
Create a formula property in the class mapping:
<property name="TotalRecords" formula="count(*) over()" type="Int32" not-null="true"/>;
IList<...> result = criteria.SetFirstResult(skip).SetMaxResults(take).List<...>();
totalRecords = (result != null && result.Count > 0) ? result[0].TotalRecords : 0;
return result;