Indexing (fields With Low Entropy)
Sep 20, 2007
I need an advice by indexing fields with low entropy.
I have some large tables with some columns that i use in selects, but they store only few vaues like (0 or 1) or ("R" or "N" or "F").
Somewhere i read, that fileds like these (with lov variety of values) do not need (or should not) to be indexed.
http://www.dbpd.com/vault/9801xtra.htm
Is this true also for access databases accessed via ODBC, or not?
Please give me an advice.
Marcel
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Apr 1, 2008
Indexing fields can dramatically improve efficiency by speeding up sorts and searchs. My database tracks mail sent on various mail dates to multiple customers with insurance policies that are assigned unique policy numbers. I've indexed the policy number.
Question 1: Is there value in indexing a mail date field which has duplicate values even for a given customer that has received multiple mailings?
Question2 : Should one index every field in every database ? Are there scenarios where one would choose not to index a fied ? If so, can someone provide an example ?
Thanks in advance for your assistance.
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Sep 5, 2005
I was told by an access programmer that since the total number of records that's going to be in the db is around a few thousand tops it would be a good idea to index everything as that would speed things up. Is this true?
thanks,
scratch
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Apr 4, 2007
Could anyone tell me about the pros and cons of Primary Key and Indexing?
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Oct 10, 2006
G'day,
I have a products table which contains products from 4 vendors. The records have the following fields "Vendor", "Vendor Part Number"," Description", "Unit" and "Price"
I have indexed same by Vendor Part Number and Description.
The vendor's describe the same product using different descriptions.
VENDOR ....DESCRIPTION................................... .........PART NUMBER
Acme........TEKS METAL HEX+SEAL 10X16MM 100 (PKT)..123456-01
Banner.......METAL TEKS 10X16 MM..............................93a-1234
If I search by part number the search is extremely fast.
However a search on the DESCRIPTION field looking for individual words say 'Like TEKS*' and 'Like METAL*' are very slow. Obviously the indexing on the description field is probable based on sorting the 1st character of the Description field by A-Z then the second character etc.
I am wondering is there a smart way of indexing the Description field at the point of importing or creation of the Products Table where I could identify all the records with say 'TEKS' or 'METAL' or '10X16' etc. By doing this the search should be a lot faster.
Has anyone done this or do you have a pointer to an article that covers this. (I did try the search function without a suitable result)
Thanks in advance
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Mar 21, 2008
In my table, I have a number field set to Index (dups OK). I have another field that I do not want to index but need "no dups." Any ideas?
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Dec 14, 2005
Hi folks!
I'm a new user and need a hand. I'm running a query with two tables joined. I have 4 columns: Name, Day of Week, Date, Start Time. I want to create a 5th column that will number each record: 1,2,3,4,etc. I've tried researching help with indexes and primary keys etc. The main reason that I want to do this is to match up the uniques value with another query. The other query is identical with the exception of stop time versus start time. Bottom line is I want to automate a schedule for people but I'm trying to deal with shifts that go from one day into the next and I need a common denominator.
Any help would be appreciated.
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Oct 23, 2006
Hello All
I have a field called MEMBERID
I wish to index the following so that all members in 2005 can be idexed A to Z and all members in 2006 can be indexed A to Z:
00125/05
At the moment, the last two digits that indicate the year of joining are ignored when sorted in a query, and they are all jumbled up. I have about two hundred antries for 2005, and 160 for 2006. What am I doing wrong?
Regards
Terence
London
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Dec 30, 2004
I have an Access 2000 customer database with a hidden unbound text field that feeds customer history notes into a Main Notes section. The problem I have is the order of notes after they are given a default time stamp. At the moment the first note in the main field is the oldest but I would like to arrange the notes so that the newest note is placed at the top of the field. Can this happen?
Below is the code I use for the Notes section, where Text_14508 is the unbound hidden text box and Details is the Main Notes section.
Thanx in advance
Private Sub Text_14508_AfterUpdate()
Me.Details = Me.Details & vbCrLf & Now() & vbCrLf & Me.Text_14508 & vbCrLf
Me.Text_14508 = ""
End Sub
Private Sub Open_Notes_Click()
Text_14508.Visible = True
End Sub
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Jan 2, 2014
I have a complex series of calculations to perform, and I have found the best way to achieve my end is to create new tables by the Make Table queries.
The trouble is I have many tables to create and the downstream tables refer to the previously created tables; I have recently discovered that queries perform much quicker if they are indexed (duplicates OK). I've looked at my tables created by the MakeTable queries, and they all seem not to be indexed.
How do I make them indexed automatically?
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Mar 19, 2013
I would like to Create a database for indexing / organizing PDF documents. My Company currently use a 3rd party accounts program and we raise sales and purchases using numerical numbers ( but we can Jump to a new range of numbers within the program) for example if the purchase order numbers become simliar to the sales order numbers. But this 3rd party software does not let us scan documents into it hence the need for an alternative database.
For the data base I was thinking if only creating a index of the sales order numbers to start with. the first few question I have are.
1.) Should I Use the Autonumber as my first index column or should I replace it with our own sales order numbers in that column.
2.) is there a way to autopopulate the sales order numbers in a table for historical sales numbers.
3.) can you scan directly into Access
How to start planning the design off the database as I know this is almost the most important aspect of a database.
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Nov 26, 2007
I don't have any database experience whatsoever so please go easy.
I'm guessing this kind of this is extremely simple for all of you.
I'm constructing a database of network resources and devices and I'd like to automatically update the values in one field based on the values of a field in another table.
The first table is called "IP" and the fields are called "Address", "IP Type" and "Device".
The second table is called "Devices" and contains the fields "Name", "Description", "Asset Number" and "IP".
Here's an example of the tables: (ignore the "code" tag. i've only used it to align my columns properly)
DEVICES:
NameDescriptionAssetIP
XserveFile Server107203.30.144.75
ProliantXDHCP119203.30.144.15
IP:
AddressIP TypeDevice
203.30.144.75Static
203.30.144.15Static
What I want is for the Device field in the IP table to automatically update it's values based on the values found in the Devices table. In this case, the values that should appear in the Device field in the IP table are "Xserve" and "ProliantX".
I've searched through but haven't found a complete solution, just little pieces which I'm too inexperienced to put together myself.
thank you
-Tim
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Apr 13, 2008
I created a form in Access that retrieves data from a table. Inside the form, I am able to access/populate data fields with data from the table. I also have data fields, inside the form, that requires key-in data. I have some how lost the ability send all data field information to a second table and clear existing data fields for new entry.
Questions: What settings, code or buttons can I use to send/store data field information to a new table? What settings, code or buttons can I use to automatically clear all data fields from my form once data has been sent to the new table?
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May 17, 2007
I have main form and that has one sub-form , this Main form governs/determines the data in the sub form.
This Sub form ( DataSheet Mode) has approximately 130 columns and based on the Main form criteria only ~ 20 columns has to be filled.
What I want to do is based on the main forms criteria I want to show only the columns that are applicable to main form criteria.
If I use Columnar or Tabular single form for the Sub Form I am able to hide the fields that are not required BUT IT LEAVES A SPACE/GAP on form ( for the hidden fields that are not required)
Private Sub Form_Load()
If Forms!frmShowPIforActiveAndCanAddNewPI!FrmSubFrmFi lterProductInformationPerFMT!CASETIF = True Then
Me.CASETIF.Visible = True
Else
Me.CASETIF.Visible = False
End If
End Sub
And If I use DataSheet and hide ( visible = no) a particular filed it still shows up in Sub Form
Is there a way to Auto-Re Arrange all the fields in the sub form so that the hidden ( visible = no) fields no not leave gap
Or is there a way by VBA program to select fields ( Columns) from a table to be displayed on a sub form based on a criteria
Thanks
Rahul
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Jan 29, 2014
I have a totalquery that runs fine and give me the sum for both fields I'm looking for but I can't get the outputs to fill the fields on the form. I have tried the Dcount query in the control source but that just returns an error and locks up access.
Code:
SELECT [Tble-wcDelays].Causedby, Sum([Tble-wcDelays].HoursDelay) AS SumOfHoursDelay
FROM [Tble-wcDelays]
GROUP BY [Tble-wcDelays].Causedby, [Tble-wcDelays].LinkingID
HAVING ((([Tble-wcDelays].LinkingID)=[Forms]![Frm-ePlusCent]![cleanID]));
That is the query.
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Jun 28, 2015
I have a query that creates counts of fields based on the data in other fields, basically it tells me that in a table there are two entries with value ABC????? and three of DEF????? , the query works perfectly.
When I create a form to display this data and base the form on the Query I keep getting a message box asking for the ID (key field) from the base table.
If I type * in the box (to denote all values) and press enter I get the results expected.
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Nov 18, 2013
Basically in my order details table i have the following fields
Product
Unit
Size
At the moment i have the Product field with a dropdown that gives me all the products from my ProductT. But once i choose the correct product in the unit field it gives me all the possibilities of every product not just the units associated with that product. ie
ProductT
Grasshopper Box1000 Adult
Grasshopper Box1000 Subadult
Worm 10pz Big
When I select the grasshopper product and move on to the unit field i also get "10pz" option but this is not a product available.
How do i set up validation of the fields Unit and size based on another fields data?
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Aug 27, 2013
I have a database that will register the emails coming in and what time, also the time, date out and person.
I have a form with the fields to be filled in and a submit button. There are some fields that are automatically filled in and others need manually fill in.
below that part is a sheet (subform in the form of sheet) that should be filled in with the above data. Once it is there, it should empty the fields so they are ready to be filled in again. If I fill new data and press the submit button, it should go to the next available row.
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Aug 21, 2013
I have a copy of the back-end that gets a search key error 3709 on two records. In other words, I can duplicate the problem.
The interesting part is that I can update any other field on both these records and save the record, but when I try to change two specific fields, I get a Search Key Error and have to ESC out to continue (basically UNDO the change). Both fields are text fields with lengths of 7 characters and 255 characters, and both are COMBO Boxes on the form.
I tried to focus on the form think there was an issue in the code. I can definitely TRAP the 3709 error on the ON ERROR event on the form using "if dataerr = 3709", but then I tried something even simplier.
I went directly to the table and to each of the records. Again I can update any other field in the record but these two specific fields. When I try to change either of them and move to another record, you get a Search Key Error 3709.
By going to the table record directly I'm as low level as I can get. There are no validation rules on either field at the database level. If it was truly CORRUPT would it let me update any of the other fields on either of these records? One is an empid (not a primary key but is indexed with duplicates okay and not required), and one is status code (not a primary key but is indexed with duplicates okay and not required) so they're no critical fields, but something is keeping them from CHANGING.
Just tried something else; deleted the INDEXES on both the fields. Now it works! I am completely confused now because it really wasn't a corrupt record, but the indexes are causing the problem. Do I need to update the indexes somehow when the users selects a new empid or status code?
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Apr 22, 2015
I have a product table that includes the name of the product, the quantity ordered, and the unit price. This is a summary table for the whole year showing all of the orders. The Primary Key is [ID] from the [tblOrders] table. I attached a screen shot of my query. I don't know if you can see it. I want to generate a report where each product is listed once, the unit price for that product is listed, the total number of that item that was ordered throughout the year, and finally, the total amount spent for each item during the year.
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Nov 2, 2005
How can I get some mainform fields' data to be the first entry in a subform? From the mainform, I would like the Head of Household name and date of birth to be carried over to the first entry in the HouseholdMembers subform.
The two forms are tied to separate tables. For each household member I need to be able to enter full legal name, date of birth and some additional pieces of information such as income and source of income.
What I'd like to avoid is making the users enter the Head of Household's name and date of birth twice. Is there a way to carry that information over to the subform?
Thank you, Charlotte
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Jun 20, 2006
Hey Everyone,
I am stuck trying to figure out this problem. I have a main form "frm_tirelog_600" which has 4 combo boxes "cboleg",
"cbocar", "cbopos", "cboserial" on it. The first 3 combo boxes are used as criteria on 1 of 3 subforms that I have.
The fourth combo box "cboserial" is used for the criteria in a query on another subform that I have called "frm_mount_600_subform",
which is independant from the main form, I hope I have explained that clearly enough. What I need to be able to do is
have the subform fill in 3 of the fields on it "leg", "car", "pos" with the value from the 3 combo boxes on my main form. I
can get it to show in the fields but not write to the table. I have searched the forum and have not been able to locate anything
that would work and really need any assistance with this. Im not real strong in the coding department which is where I
beleive this could be done.
I have attached a copy of my DB which I hope will better explain it. Any help would be greatly appreciated
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Aug 30, 2004
I have a combo box linked to a look-up table. There are 8 fields in the look-up table but only if one of three is chosen do I want additional combo boxes to become visible. Do I put the code in the "after update" or "on change" event of the combo box and how do I express the code-
If TechniqueCombo="caudal" or "spinal" or "epidural" then
TextNeedleType.Visible=True
(am I close??)
Thanks
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Aug 28, 2006
Hey,
The database I am working on, I split a while ago to give it some security. Now i'm updating a related form, and i'm finding that if I delete and add fields in the BE, the FE fields (being the fields that I need to insert into the form so the data entered propogates to the DB) are not updated.
How do I update the FE?
Thanks.
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Aug 15, 2013
I reached the limit of 255 fields in a table. I just need to add one more field so I deleted several fields I no longer needed thinking I would then be able to add one more new field. However, I am still unable to add one more field. How to free up fields that are no longer needed?
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Aug 4, 2005
I have two tables - Hours and Employees. Employees table has these fields:
EmpID, and First, and Last name.
Hours table has these fields:
EmpID, Hours, Funding Source, Nature of Work, Pay Period
I need to produce a report or a query that will display these results:
A column with a list of all the employees and all the Nature of Work categories going across with the sum of hours for each Nature of Work. I'm attaching an Excel spreadsheet that shows kind of what I need. Also, these reports need to be produced for each Funding Source and
Pay Period, so something like [Enter Funding Source] and [Enter Pay Period]
My question is that I don't know how to make a report that will just list a column with all the names and count the sum of hours for each Nature of Work.
Hope this is not too confusing, and any help would be greatly appreciated. thank you!
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