I have a two table scenario with a typical parent / child relational setup:
tblGroup - idGroup (autonumber, PK); GroupName (Short Text), Rank (Number)
tblRange - idRange (autonumber, PK), idGroup (FK -> tblGroup.idGroup), RangeName (Short Text), Rank (Number)
What I am doing on the parent (tblGroup) table is using a data macro to add the rank using the BeforeChange event:
IF
IsInsert
SetField - Rank
- DMAX(Rank, [tblGroup])+1
This works nicely and I can happily use a parametized INSERT query to add rows to the table and not have to worry about duplicate ranks and so forth.
What I would like to be able to do but cannot figure out how, is to have a data macro do the same thing for the child (tblRange) table, with the rank being set to the new highest for the parent group the child record belongs to.
If I use the same DMAX approach as I have above I am supposed to be able to set a criteria as a third option, acting like a where clause, to limit the lookup / calculation. How can I refer to the specific idGroup I am working with in tblRange in the macro? I cannot seem to figure out how to reference the new records value for this in the macro.
Something like DMAX(Rank, [tblRange], ???How_to_refer_to_idGroup_Properly???)+1
Any help greatly appreciated
Cheers
The Frog
I figured out a way to do this. Thankyou caffeinated beverages!
The reason for the strange error messages is due to limitations in the Data Macro processing, specifically in the BeforeChange event. The solution is as follows:
Create a query that selects MAX rank (MaxRank) and GROUP BY for the idGroup (ParentID)
The resultant query produces two columns of data: [MaxRank] and [ParentID]
There will be a row for every idGroup with the maximum Rank for each
Create a BeforeChange data macro
Set the following:
IF IsInsert
LookupRecord
Lookup Record In - qryGetMaxRank (or whatever you called your query)
WHERE - [qryGetMaxRank].[ParentID] = [tblRange].[idGroup]
Set Field
Name - [tblRange].[Rank]
Value - [MaxRank] + 1
The BeforeChange event cannot handle parameters for a query, and I am guessing that this applies in some form the to DMAX function here too. The use of a query that does not use any parameters, and then using the LookupRecord WHERE clause to do the filtering provided the single row result needed. The [MaxRank] value from the returned result is then able to be used to set a new value for the field.
Bit of a workaround but it does allow someone to work with the data either through a form or through the datasheet view and not create a problem.
**In answer to if this is a multi-user DB - it is not. It is just me working with it. If / when the solution is scaled up to something requiring multi-user I will likely recreate the BE in SQL Server or MySQL and use stored procedures for all data I/O. Happy to keep Access as the FE and compile into an application (using the runtime for clients), but I am a fair way off from having to do that yet. Very early stages of development at this time.
Cheers to everyone for the pointers. They helped me figure this out. Hopefully this will be of use to someone else in the future.
PS: If you need to use a parametrized query in a data macro it looks like the best bet is with the AfterInsert event or AfterUpdate event as they can support parameters.
Related
I am looking for an Idea to handle data in DB directly.
Here is my use case
I have table “EVENT_REGISTERED” with column (ID, Event_name,Event_DateTime)
I want to display the EVENT_REGISTERED in the fronted end whose date and time is not passed. i.e. I want to display only Upcoming event not Historical events.
Of course this can be handle with JS code before displaying.
But What I want is there should be some sort of a trigger which will delete the Instance form the “EVENT_ REGISTERED” table and copy it to another Table “HISTORICAL_EVENT”
I cannot Create an MY SQL EVENT to do this as it like batch job and I cannot run this every 5 mins as there can be more than 10000 rows in there.
I see Trigger option as well, I am not sure how to use this as it says that it will be activated after the specific action is executed. Here the specific action is CURRENT_DATETIME == EVENT_DATETIME.
Can anybody give me a direction or any sort of alternative way to achieve this?
**I am not an Expert of MySQL*
Thank you
Regards
Prat
Don't start moving rows between tables. Simply run a query:
select er.*
from event_registered
where er.event_datetime > now();
With an index on (event_datetime), performance should be fine.
I have a table that contains all the weeks of the year (using the client's numbering, so Week 1 is in June), and the dates they start. There is a form where they can choose which week they want to look at, so I've used a ComboBox that grabs all the week numbers for which they've entered data in the WeeklyHours table, using
SELECT Format(WeeklyHours.Week,"0") AS Expr1 FROM WeeklyHours GROUP BY WeeklyHours.Week;
This combobox is then supposed to be used as the week filter for a couple queries I've built, using the combobox value as the matching criteria. The problem is that when the form is closed, those queries can't run, and give me the Enter Parameter Value error for the combobox value.
To fix this, I tried to create a new table called SelectedWeek with a single entry called Week_Number. There is then some AfterUpdate code that saves the selected combobox value to the Week_Number field of SelectedWeek.
I then changed the queries to point to [SelectedWeek]![Week_Number], so that the queries will always use whatever the most recently selected week was.
However, I keep getting the Enter Parameter Value error for SelectedWeek!Week_Number, and I can't figure out why.
Any help would be most appreciated.
Thanks,
Joel
Reason the user is prompted for Parameter Value (by the way, it is not an error) is in both cases the Access SQL engine cannot see either referenced values. In first case, the form is closed and in second case column is not properly aligned to a lookup.
In first scenario, simply keep form open which user selects value from combobox when running other queries. Otherwise, all content on form is not callable since it is closed from memory:
SELECT * FROM TableName WHERE weeknumber = Forms!FormName!WeekNumber
In second scenario, use a DLookUp() part of the Domain Function Family.
SELECT * FROM TableName WHERE weeknumber = DLookUp("Week_Number", "SelectedWeek")
And really, domain functions can be generalized as subqueries in SQL:
SELECT * FROM TableName
WHERE weeknumber IN (SELECT Week_Number FROM SelectedWeek)
Even more, you can run a cross join query (tables separated with commas in FROM clause) of the two tables and avoid lookups. Below assumes SelectedWeek is a one-row, one-column table but with the WHERE condition, length is handled and you can explicitly declare columns in either table:
SELECT *
FROM TableName, SelectedWeek
WHERE TableName.weeknumber = SelectedWeek.Week_Number
I have a query in a base-data table that (given that my search criteria are correct) gives back approx. 950 records.
Except of the 3 criteria fields, i want to have about 10 more fields (the Project is still at the beginning) , every single one based on sub-queries, some of them normal select queries, some are aggregated queries.
As far as i know every sub-query must give 1 and only one value back.
This value school be individual for every Record of the top query.
My Problem now is, that i don't know how to pass the search criteria from the top query (simple select query) to the sub-query in the in 10 fields i mentioned before.
Is this possible at all, or is my Approach to complicated. Is there possibly an easier way?
I have a Windows 7 System with Office 2010 installed.
Your help is much appreciated.
Thanks a lot.
PS
The sub-queries are based on the same table as the top query. Sorry, I forgot to mention.
You can pass arguments between things with a function call to set a public variable. This vba must be in a Module, not behind a Form Module. I don't use this approach very often, because the global value is in volatile memory, I prefer to save the variable in a special data Table.
Public strGlobal As String
Function Func_ReadGlobal() As String
Func_ReadGlobal = strGlobal
End Function
Function Func_WriteGlobal() As String
strGlobal = Func_WriteGlobal
End Function
In all subqueries create parameter(s) and use it as search criteria. Parameter name should be the same for same column. Now, if you use those subqueries in your main query, Access will ask only once per each parameter name, you don't need to pass them explicitly to subqueries.
Thank you guys.
I did'nt think of the most obvious solution with the Globals. I will try it out as soon as my Boss gives me the time to continue with the Project.
#Sergey
I can't use the Parameter(s) way, because the whole query, incl. Subqueries shall run completely alone in VBA, without human input at all.
We're trying to create a template date prompt to be used across multiple universes, and also be used against multiple date fields (for instance, Transaction Date, Invoice Date, etc)
The prompt should display a list of values like the below (there's about 30 total):
Date Range START_DATE END_DATE
-------------------- ------------------------------ --------------
D: Yesterday 12/02/2015 12/03/2015
M: Month Before Last 10/01/2015 10/31/2015
M: Month to Date 12/01/2015 12/02/2015
Our initial attempt at this (creating a derived table, and then some aliases against the derived table, with one alias for each date type such as Transaction Date, Invoice Date, etc) was a failure - the sql generated is wrong, and includes the sql that's just supposed to provide the list of values. I think we need to use a different approach entirely.
Thanks for reading so far. I would greatly appreciate any ideas! Feel free to ask questions and I'll edit my notes to answer.
EDIT - we're using UNV (legacy Universe Design tool)
I'm going to assume you have an existing (dimension) table that contains a record for each date and the necessary columns to hold the different representations. You can also create a derived table for this.
Here are the steps to achieve what you described (sorry, no screenshots, this is off the top of my head):
Create the required dimension objects (based on your date table) in a separate class in the universe (you can hide this class at the end; the end user shouldn't see them).
Take one of the date dimension objects (e.g. Transaction Date, Invoice Date. …), enable the LOV option and edit it (which should bring up the query panel).
In the query panel, select all the dimension objects, created in step 1, that you want to show in your LOV. Important: the object holding the value to be returned, should be placed first in the query panel. Run the query (nothing will appear though).
Make sure that you enable the option to Export the LOV, otherwise your customisations will be lost upon exporting the universe. Optionally, enable the option to refresh the LOV each time the user calls it.
As you can't really define a single, reusable LOV in UDT that you can reference in different dimension objects, you'll have to perform this for each dimension object that you would want to have this LOV.
One way around this annoyance may to define the customised LOV once, note down the generated LOV name (about 8 alphanumeric characters long) and then replace the LOV name in the other dimensions with that LOV name. I'm can't guarantee that this will work though.
In contrast: with IDT you can define a customised LOV like this once (either in the Data Foundation Layer or the Business Layer), and then reference it as much as you want.
I have two tables and from that I am generating a query. I have columns in my query with field type yes/no. These are basically columns to determine the race of a person. The user enters information in yes/no for various races. I want another calculated column in the query which checks for all other race columns and calculates values in it.
I have to check for a few conditions in for the values in columns
For example:
1) If Hispanic is chosen, the new column should say hispanic(no matter what other options are selected. This is like a trump card)
2) If more than one is selected, then new column entry should say "multi"
3) If none of the options are selected, it should say "unknown"
4) If exactly one of them is selected, then that race should be displayed
Can anyone help me with this? I am new to Access
I can't code it for you but I can point you in the right direction. What you want to do is take all the tests you explained above and put them in a coded format :
iif ( condition, value_if_true, value_if_false )
Since you have a lot of possible outputs i'd use something like a Case Statement where you can test for all the possibilities.
Follow this link if you need any info on how to code both type of statements (iif and case).
Once you have tried something like this, you can comeback with a specific question if you encountered a problem in the process.
Good luck with your database.