Sharepoint - Querying a simple list with a 'User' column, using CAML
Try to use this caml:
<Where>
<Eq>
<FieldRef Name="Author" LookupId="True" />
<Value Type="User">123</Value>
</Eq>
</Where>
this also might work, but first is preferable:
<Where>
<Eq>
<FieldRef Name="Author" LookupId="True" />
<Value Type="Lookup">123</Value>
</Eq>
</Where>
and also, if you want to pass current logged user into caml query, you can use this one:
<Where>
<Eq>
<FieldRef Name="Author" />
<Value Type="Integer">
<UserID />
</Value>
</Eq>
</Where>