Today I'll show you how you can get the minimum or maximum value of the field in SharePoint list.

Solution

The solution lies in the fact that we simply sort the elements in this field from the previous to the late receipt at the minimum value (or vice versa to obtain the maximum). Also, we will limit the number of elements of one.

For convenience, I made a method for the extender SPListItem, which takes as a parameter to the internal name of the field. Here I will give methods for obtaining the maximum value. Getting the minimum value will differ only in the direction of sorting.

/// <summary>
/// Maximum value of the field in the list
/// </summary>
/// <typeparam Name="T">type values ​​in the field </typeparam>
/// <param Name="list">List</param>
/// <param Name="fieldInternalName">Internal name of the field </param>
public  static  T GetMaxValue <T> (this  SPList list,  string  fieldInternalName)
{
    var  query =  New  SPQuery
    {
        // Take the only field that we are interested in
        ViewFields =  string . Format ( "<FieldRef Name='{0}' />" , fieldInternalName),
        // Build a query
        Query = string.Format(@"<OrderBy><FieldRef Name='{0}' Ascending='False'/></OrderBy>", 
        fieldInternalName),
        // Get only the first row
        RowLimit = 1
    };
    // Execute a query
    var  items = list.GetItems (query). Cast <SPListItem> ();
    // If the collection is empty (for example, the list contains no elements) 
    // Then return the default value for type
    if  (items.Count () == 0)  return  default (T);
    // Return the value of the field
    return  items.First () [fieldInternalName] is T
        ? (T) (items.First () [fieldInternalName])
        : default(T);
}

To increase the functionality, you can add one more parameter - wherePredicate and CAML-transfer request for pre-filtering the data. You will be able to filter out null values ​​before the search for the minimum value, for example:

/// <summary>
/// Maximum value of the field in the list
/// </summary>
/// <typeparam Name="T">type values ​​in the field </typeparam>
/// <param Name="list">List</param>
/// <param Name="fieldInternalName">Internal name of the field </param>
/// <param Name="wherePredicat">Predicate for the pre-filter </param>
public  static  T GetMaxValue <T> (this  SPList list,  string  fieldInternalName, 
                                   string wherePredicat)
{
    var  query =  New  SPQuery
    {
        // Take the only field that we are interested in
        ViewFields =  string . Format ( "<FieldRef Name='{0}' />" , fieldInternalName),
        // Build a query
        Query = string.Format(
            @"{0}<OrderBy><FieldRef Name='{1}' Ascending='False' /></OrderBy>", 
            wherePredicat, fieldInternalName),
        fieldInternalName),
        // Get only the first row
        RowLimit = 1
    };
    // Execute a query
    var  items = list.GetItems (query). Cast <SPListItem> ();
    // If the collection is empty (for example, the list contains no elements) 
    // Then return the default value for type
    if  (items.Count () == 0)  return  default (T);
    // Return the value of the field
    return  items.First () [fieldInternalName] is T
        ? (T) (items.First () [fieldInternalName])
        : default(T);
}

Using

For example, to maximize the creation date and maximum values ​​of ID:

var maxCreated = list.GetMaxValue<DateTime>("Created");
var maxId = list.GetMaxValue<int>("ID");