The problem to be aware of is related to SPQuery objects that have the LookupId set to TRUE and the Value Type set to Lookup. An example:

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SPQuery oQuery = new SPQuery();
 
oQuery.Query = "<Where><Eq><FieldRef Name='Employee' LookupId='TRUE'/>" +
            "<Value Type='Lookup'>161</Value></Eq></Where>";

With a NON indexed column, the above query works fine. Once you change the Employee field so it is an indexed column, the above query will fail to work. Changing Value Type from Lookup to Integer seems to make it work again. So somehow, something is changing when a column is indexed thus causing the query to behave strangely.

Removing the index on that column makes everything work magically again. Thanks to the following post for affirming what we had already painfully discovered.

Scenario 1

Get me all items in a list WHERE fullName equals the currently logged in user.

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SPWeb web = SPControl.GetContextWeb(Context);
 
string fullName = web.CurrentUser.Name;
 
SPQuery oQuery = new SPQuery();
 
oQuery.Query = 
    "<Where>" + 
    "<Eq><FieldRef Name='FullName'/><Value Type='Text'>'" + fullName + "'</Value></Eq>" + 
    "</Where>" +
    "<OrderBy><FieldRef Name='StartTime' Ascending='FALSE'></FieldRef></OrderBy>";

Scenario 2

Get me all items in a list WHERE fullName equals the currently logged in user AND status equals ‘Complete’.

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SPWeb web = SPControl.GetContextWeb(Context);
 
string fullName = web.CurrentUser.Name;
 
SPQuery oQuery = new SPQuery();
oQuery.Query = 
    "<Where>" +
    "<And>" +
        "<Eq><FieldRef Name='FullName'/><Value Type='Text'>'" + fullName + "'</Value></Eq>" +
        "<Eq><FieldRef Name='Status'/><Value Type='Text'>Complete</Value></Eq>" + 
    "</And>" +
    "</Where>" +
    "<OrderBy><FieldRef Name='StartTime' Ascending='FALSE'></FieldRef></OrderBy>";

Scenario 3

Get me all items in a list WHERE fullName equals the currently logged in user AND status equals ‘Complete’ AND manager is James Lane.

This is where it gets a bit tricky. The following example is INCORRECT and will produce an error when run:

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SPWeb web = SPControl.GetContextWeb(Context);
 
string fullName = web.CurrentUser.Name;
 
SPQuery oQuery = new SPQuery();
oQuery.Query = 
    "<Where>" +
    "<And>" +
        "<Eq><FieldRef Name='FullName'/><Value Type='Text'>'" + fullName + "'</Value></Eq>" +
        "<Eq><FieldRef Name='Status'/><Value Type='Text'>Complete</Value></Eq>" +
        "<Eq><FieldRef Name='Manager'/><Value Type='Text'>James Lane</Value></Eq>" +
    "</And>" +
    "</Where>" +
    "<OrderBy><FieldRef Name='StartTime' Ascending='FALSE'></FieldRef></OrderBy>";

This is the correct way to do it:

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SPWeb web = SPControl.GetContextWeb(Context);
 
string fullName = web.CurrentUser.Name;
 
SPQuery oQuery = new SPQuery();
oQuery.Query = 
    "<Where>" +
    "<And>" +
        "<And>" +
            "<Eq><FieldRef Name='FullName'/><Value Type='Text'>'" + fullName + "'</Value></Eq>" +
            "<Eq><FieldRef Name='Status'/><Value Type='Text'>Complete</Value></Eq>" +
        "</And>" +
        "<Eq><FieldRef Name='Manager'/><Value Type='Text'>James Lane</Value></Eq>" +
    "</And>" +
    "</Where>" +
    "<OrderBy><FieldRef Name='StartTime' Ascending='FALSE'></FieldRef></OrderBy>";

Scenario 4

Get me all items WHERE fullName equals the currently logged in user AND status equals ‘Complete’ OR status equals ‘On Hold’.

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SPWeb web = SPControl.GetContextWeb(Context);
 
string fullName = web.CurrentUser.Name;
 
SPQuery oQuery = new SPQuery();
oQuery.Query = 
    "<Where>" +
    "<And>" +
        "<Eq><FieldRef Name='FullName'/><Value Type='Text'>'" + fullName + "'</Value></Eq>" +
        "<Or>" +
            "<Eq><FieldRef Name='Status'/><Value Type='Text'>Complete</Value></Eq>" +
            "<Eq><FieldRef Name='Status'/><Value Type='Text'>On Hold</Value></Eq>" +
        "</Or>" +
    "</And>" +
    "</Where>" +
    "<OrderBy><FieldRef Name='StartTime' Ascending='FALSE'></FieldRef></OrderBy>";

I really do recommend if you’re doing any work with CAML queries that you download the U2U CAML Query Builder 2007. It doesn’t come without it’s issues, for example, doing a query on a list with a column of type Lookup does not always yield the results I would expect, but it’s still quite helpful. I also often find myself changing the Value Type from Lookup to Text but other than that it’s a huge resource when trying to determine if the data is actually in the list or if there is a problem with the query i’ve written.

Any feedback or questions, please drop me a line.

If you dig through this post a little bit, you’ll find the technique to getting distinct values comes down to leveraging a DataView.ToTable() method to return only distinct results.

So let’s break this down a bit. A typical scenario for me is to build a data table that contains all of my data (via an SPQuery to the list), set the data source of my control to that data table and then bind.

(In my case, I work specifically with the Telerik RadGrid and the Telerik RadComboBox but the same idea applies to the standard ASP.NET controls)

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DataTable groupedDataTable = originalDataTable.DefaultView.ToTable(true, "Title")
 
dataGrid.DataSource = groupedDataTable;
 
dataGrid.DataBind();

The ToTable() method accepts two parameters as demonstrated above.

1. bool distinct simply indicates whether or not to supply distinct values
2. params string[] columnNames is a string array that contains a list of the column names in the orignal data table that you’d like to be returned

For example:

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<OrderBy><FieldRef Name='EventDate' Ascending='FALSE'></FieldRef></OrderBy>

The full query would look something like this:

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SPQuery oQuery = new SPQuery();
 
oQuery.Query = "<Where><Eq><FieldRef Name='AP_x0020__x002f__x0020_O'/>" +
"<Value Type='Text'>" + fruitName + "</Value></Eq></Where>" +
"<OrderBy><FieldRef Name='EventDate' Ascending='FALSE'></FieldRef></OrderBy>";

If you receive an error similar to:

One or more field types are not installed properly. Go to the list settings page to delete these fields.

Then you’ve set the FieldRef Name incorrectly. The trick to resolving this is:

1. Navigate to your list that the column/field is contained within
2. Click the New button as you normally would to create a new item in this list
3. Click on View, Source from the toolbar in your browser window.
4. Finally, do a find on the phrase fieldinternalname and locate the field you’re trying to query on
5. Whatever value is stored in fieldinternalname is what you’ll want to use in your query

Any questions, let me know.

UPDATE: I recently discovered another trick to this. If you want to avoid having to seek out what the internal name of a particular field is, when you first name your column, do not include any spaces or special characters. Once the field (column) has been created, go back and rename the field to include the spaces or special characters as desired. SharePoint will still retain the original field name without spaces and you can use that directly in your query without issue.