MS Access-在多值字段中查询多个答案？

Question

I am new to Stack Overflow but think I have thoroughly searched for an answer to this so I hope it isn't repetitive. I'm also a total novice with Access and SQL so please bear with me! I am learning everything as I go.

We've created a database of education programs, with many “multi-valued fields” that appear as drop-downs with check boxes. I wish we'd known beforehand that these are not the best functionality of Access, but this is the data that we have, so we will have to work with it.

My question is, in a query how can you indicate a criteria of having multiple boxes checked?

For example, I want to select and count all the records that have multiple boxes checked in the “source” field- meaning how many of these programs appeared on multiple lists we looked at?

The values are all strings. I also have started to understand that they each have an underlying numerical value that Access codes them as, but I don't know how to find out what those values are for this different lookups. Also, all of our data is stored in one table, there aren't any other linked tables.

For example:

SELECT [Database Source].Value
FROM [Database]
WHERE ([Database Source].Value = **TWO OR MORE VALUES**)

I just can't figure out what the criteria syntax is to indicate TWO OR MORE VALUES . So far my only way of doing it is to create the combinations for each one:

WHERE ([Database Source].Value = Source 1 AND Source 2) OR ([Database Source].Value =  Source 1 AND Source 3) OR *(And so on)*

I hope there is a more efficient way to do this than typing out all possible combinations.

Any guidance is much appreciated. Thank you!

Answer 1

I'm looking here: https://support.office.com/en-us/article/Using-multivalued-fields-in-queries-6f64f92d-659f-411c-9503-b6624e1e323a

Okay, if I understand right, "Database" is the name of your table and "Database Source" is your multi-value field. (I have to note that Database is a very confusing name for a table in this context since it makes the sql look like we are referring to database properties)

Your multi-value field is basically abstracting a one-to-many relationship in a weird wizardy way. Your [Database Source] holds a list of ids, and the id's associate with another table that has your possible values. If you refer to [Database Source].value in your query then you break your multi-values into separate rows, so you don't want to do that.

It looks to me like you need to have another field in your column to group on. If you have an ID column that would work.

SELECT Database.[field x],Database.[Database Source] 
FROM Database
GROUP BY [field x]
Having Count(Database.[Database Source]) > 1;

Answer 2

First, build a string from your selected values. Then, use that string in an "IN" clause. Like this:

Dim strSQL as String
Dim vItm as Variant
Dim rec As DAO.Recordset

For Each vItm In Me!Listbox.ItemsSelected
    strSQL = strSQL & ListBox.Column(0, vItm) & ","
Next vItm

strSQL = left(strSQL,len(strSQL) - 1) ' remove last comma

Set rec = CurrentDb.OpenRecordset("Select * FROM MyTableName " _
    WHERE MyFieldName In (" & strSQL & ")")

I'm not sure which column in your listbox actually holds the value you want to search on, if I knew the code that fills your listbox I could be more specific but the code above assumes your value is in the first column. The Columns collection is zero-based, so Column(0) is the first column, Column(1) is the second column, etc...