I have a form with a subform linked by the field DataType, which displays all the data for that DataType and has been working well for years.
The DataType can be further filtered by several dropdown fields, the fields are parameters in the underlying query for the sub-form, but if these fields are blank it will return all the data for that DataType, and I have a 'Clear all' button that runs code to make all the filter values null/blank except when all the fields are blank all the data is not being returned. I have narrowed the issue down to one field DataFilterC. For some reason the query is no longer treating the field as null/blank even when it is, it will work if I choose an option for it's drop down, this is the criteria for that field;
Like IIf(IsNull([Forms]![Form]![SubForm1].[Form]![DataFilterC]),"*",[Forms]! [Form]![SubForm1].[Form]![ DataFilterC]) Or Is Null
The query skips the first IsNull and goes straight to the final Or Is Null what could be causing this?
Deal with possibility of either Null or empty string with:
IIf([Forms]![Form]![SubForm1].[Form]![DataFilterC] & "" = "", "*", ...
Related
I have an Access data table with the Field "RequiredUntil", which is from the type "Date/Time", and several other columns, and a form, in which I show that table, and where I usually use right mouse click to filter for what I want. The text box for "RequiredUntil" is formatted as "Short Date".
Part of the form:
When I now do a right click on the field "RequiredUntil" in that form, Access properly recognizes that as a date, and offers me several date filters, i.e. Today, "This week", Past,... So I don't use any SQL there, all is done by Access!
When I select "Today" (or Yesterday or Tomorrow), I get a "Data type mismatch in criteria expression" error.
When I select "This week" (or any other time period), the filter is properly set - but as soon as I filter the next column, I get a
Syntax Error in Query expression '((Year([DataTable].[RequiredUntil])=Year(Date())) AND
(DatePart("ww";[DataTable].[RequiredUntil];0)=DatePart("ww",Date(),0))'.
In that case, the date filter is revoked, and only the second filter is applied.
So, I don't do any SQL, RequiredUntil is of the type Date/Time, the text field in the Form is Date/Time, Access recognizes it as Date - what am I missing?
I'm pretty sure, the issue is caused by Null values in your date field.
If removed, you can set the filter, which will reveal as:
(DateSerial(Year([DataTable].[RequiredUntil]), Month([DataTable].[RequiredUntil]), Day([DataTable].[RequiredUntil])) = Date()+1)
which, obviously, will fail, as DateSerial doesn't accept Null values.
As the subject expresses, I'm trying to sum the values of a string field where spaces may exist. It must be done this way, unfortunately.
The database is very old. The original developer chose to make all fields Text fields; to get over the null value problems, a function was written in VB6 to replace any null value with a space. This cannot be changed.
Fast forward to now, I'm trying to create a report that sums the length field without changing spaces to nulls first, and it should be done entirely through the control source property of the report.
I've added some of what I've tried below, but every time the report is run, I receive:
Data Type Mismatch
...and I'm not sure how to get around it.
Ideally, I'd like to keep the users out of the database completely, and just add a combo box that lists the reports created in the database so they can be opened by name without having to run any additional update queries first.
=Sum(IIf([MY_LEN]<>" ",DCount("[MY_LEN]","MY_TABLE"),0))
=Sum(Nz(Iif(Trim([MY_LEN])='',Null,[MY_LEN]),0))
=DSum("[MY_LEN]","[MY_TABLE]","[MY_LEN]<>' '")
=Sum(Iif(Val([MY_LEN])>0,[MY_LEN],0))
=(SELECT Sum([MY_LEN]) AS MyLen FROM MY_TABLE WHERE (((MY_TABLE.[MY_LEN])<>' ')))
Is this possible?
Can't compare anything to Null. Can't say If x = Null Then because Null is undefined. So you can't test if undefined = undefined. Use If IsNull(x) Then in VBA and Is Null in query criteria. Don't really need IIf() for Sum() aggregate, other aggregates such as Count or Avg would.
To handle possible space, empty string, or Null for a text field holding numeric data.
=Sum(Val([MY_LEN] & ""))
I'm creating a single SSRS report that is composed of data drawn from different Datasets. What I'm wanting to do is have a drop down menu where the user selects the dataset they wish and have the appropriate table turn on and show them the dataset information.
Right now I'm testing with two tables and in there Visibility property I have the following expression:
=IIf(Parameters!AppSelection.Value = "STRAW", false, true)
The other table has the exact same line in the same place but with a different value between the quotes.
With my parameter, I created a new one and called it AppSelection and gave it 2 Available Values that matched the words between the quotes in my above expression. The data type for my parameter is Text and the Value of the each Available Value is left at null.
When I preview my report and select the different values in the parameter, nothing happens. What is it I'm doing wrong?
Change the null in the available values to your text, ie STRAW.
You may find that the tables show the other way round from expected, switch the true and false.
I'm trying to make a MS Access report, where I use a text box to display a field value, then have another text box indicating if the first value is higher or lower than an entry in a separate table.
The report has a record source of "Table 1", and a textbox named "txt_Value1" which displays the number in Field: "Value1". I have a second table, "Customer_Criteria" which has a field "PassValue" that I want to compare against. My expression builder statement is:
IIf([txt_Value1]<(DLookUp("[PassValue]","[Customer_Criteria]","[Customer] = 'ABC'")),"TRUE","FALSE")
This statement always returns false, regardless of what the correct logical result is.
I've tested it, writing:
IIf(1<(DLookUp("[PassValue]","[Customer_Criteria]","[Customer] = 'ABC'")),"TRUE","FALSE")
And I get the correct results. Also, if I write:
IIf([txt_Value1]< 1,"TRUE","FALSE")
I get the correct results. What am I missing to compare the textbox value vs. the Dlookup?
As I understand, both fields are numeric. Access may consider those fields as text, so for correct comparing use type conversion.
Try this:
IIf(CLng(Nz([txt_Value1],0))< _
CLng(Nz(DLookUp("[PassValue]","[Customer_Criteria]","[Customer] = 'ABC'"),0)), _
"TRUE","FALSE")
Nz required if fields may contain NULL values, in this case type conversion function will return error.
I have a function that essentially copies records and inserts them with new IDs. The code works and everything copies fine.
The SQL that occurs is essentially:
INSERT INTO myTable (ID, field, select) VALUES ('newID','stuff','')
Notice the last value is blank,empty,null, whatever. Sometimes it has something in it, sometimes it doesn't.
I have a check against that value in an access form and it uses isNull or isEmpty and both come up false, with only records that are inserted in this manner.
So what is being inserted, if nothing is being inserted? it's neither null nor empty and there is nothing in there, so I'm completely baffled. If I enter something and wipe it out, it'll be fine.
The IsEmpty() Function is generally only of use to check to see if a variable of type variant has not been initialised.
A database field can be said to be empty which is not the same as if it was Null.
For example if you have a field called Gender which was not a required field on a new record the value could be Null, then if a user typed in Female obviously it would a contain value. If they were then to delete the word Female then the field would now be empty (Not Null).
The most useful function to use when dealing with Nulls in Microsoft Access is the following:
Nz()
This function has two arguments, the first one being the variable you wish to check and the second one being the value you wish to return if the variable is Null. For example the following will return an empty string:
Dim variantName As Variant
variantName = Null
Debug.Print Nz(variantName,"")
Also please note if you try to join a variable that contains Null with a String using the plus character (+) then this will result in Null which is probably where you're having problems.
A try typing the following into the immediate window results are also shown here:
? len(null)
Null
? len(null + "abc")
Null
? len(null & "abc")
3
could be a \r or \n or any other non printable character,
you may want to select such a row and cast it as varbinary to see the content