SSortOrder
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Defines how to sort the rows of a table, what column to use as the sort key, and the direction of the sort.
Header file: |
Mapidefs.h |
typedef struct _SSortOrder
{
ULONG ulPropTag;
ULONG ulOrder;
} SSortOrder, FAR *LPSSortOrder;
Members
ulPropTag
Property tag identifying the sort key or, for a categorized sort, the category column.ulOrder
The order in which the data is to be sorted. Possible values are as follows:TABLE_SORT_ASCEND
The table should be sorted in ascending order.TABLE_SORT_COMBINE
The sort operation should create a category that combines the property identified as the sort key column in the ulPropTag member with the sort key column specified in the previous SSortOrder structure.TABLE_SORT_COMBINE can only be used when the SSortOrder structure is being used as an entry in an SSortOrderSet structure to specify multiple sort orders for a categorized sort. TABLE_SORT_COMBINE cannot be used in the first SSortOrder structure in an SSortOrderSet structure.
TABLE_SORT_DESCEND
The table should be sorted in descending order.
Remarks
An SSortOrder structure is used to describe how to perform either a standard sort operation or a categorized sort operation. SSortOrder structures are typically combined into an SSortOrderSet structure to describe multiple sort keys and directions. SSortOrderSet structures are used in the following functions and interface methods:
The range of allowed columns in a table that can be used as a sort key depends on the provider. Columns that are part of the current column set can always be used as sort keys. However, each provider determines whether sort keys can be defined by using available columns that are not in the current column set. An available column is a column that is returned from IMAPITable::QueryColumns when the TBL_ALL_COLUMNS flag is set.
The ulOrder member indicates both directional order and categorization information. Rows can be sorted in either an ascending or descending sequence with all NULL entries positioned last.
The TABLE_SORT_COMBINE value indicates that the column specified in ulPropTag should be combined with the previous category column to form a composite category. That is, instead of categorizing on unique values of individual columns, TABLE_SORT_COMBINE allows for categorization on unique values of a combination of columns. For example, a single category could be defined to group messages received from a particular sender on a particular subject. Setting the value to TABLE_SORT_COMBINE reduces the number of category rows that are displayed.
Sorting on multi-valued columns is not universally supported by all table implementations. If supported, apply the MV_FLAG using the MVI_PROP macro to the property tag in the ulPropTag member to identify the sort key as a multi-valued column. Sorting on a multi-valued column is based on using the individual values.
For more information about standard and categorized sorting, see Sorting and Categorization.