MDAC 2.5 SDK - ADO

Filter Property

See Also    Example    Applies To

Indicates a filter for data in a Recordset.

Settings and Return Values

Sets or returns a Variant value, which can contain one of the following:

• Criteria string — a string made up of one or more individual clauses concatenated with AND or OR operators.
  
  
• Array of bookmarks — an array of unique bookmark values that point to records in the Recordset object.
  
  
• A FilterGroupEnum value.

Remarks

Use the Filter property to selectively screen out records in a Recordset object. The filtered Recordset becomes the current cursor. Other properties that return values based on the current cursor are affected, such as AbsolutePosition, AbsolutePage, RecordCount, and PageCount. This is because setting the Filter property to a specific value will move the current record to the first record that satisfies the new value.

The criteria string is made up of clauses in the form FieldName-Operator-Value (for example, "LastName = 'Smith'"). You can create compound clauses by concatenating individual clauses with AND (for example, "LastName = 'Smith' AND FirstName = 'John'") or OR (for example, "LastName = 'Smith' OR LastName = 'Jones'"). Use the following guidelines for criteria strings:

• FieldName must be a valid field name from the Recordset. If the field name contains spaces, you must enclose the name in square brackets.
  
  
• Operator must be one of the following: <, >, <=, >=, <>, =, or LIKE.
  
  
• Value is the value with which you will compare the field values (for example, 'Smith', #8/24/95#, 12.345, or $50.00). Use single quotes with strings and pound signs (#) with dates. For numbers, you can use decimal points, dollar signs, and scientific notation. If Operator is LIKE, Value can use wildcards. Only the asterisk (*) and percent sign (%) wild cards are allowed, and they must be the last character in the string. Value cannot be null.

Note   To include single quotation marks (') in the filter Value, use two single quotation marks to represent one. For example, to filter on O'Malley, the criteria string should be "col1 = 'O''Malley'". To include single quotation marks at both the beginning and the end of the filter value, enclose the string with pound signs (#). For example, to filter on '1', the criteria string should be "col1 = #'1'#".

• There is no precedence between AND and OR. Clauses can be grouped within parentheses. However, you cannot group clauses joined by an OR and then join the group to another clause with an AND, like this:

  (LastName = 'Smith' OR LastName = 'Jones') AND FirstName = 'John'

• Instead, you would construct this filter as

  (LastName = 'Smith' AND FirstName = 'John') OR (LastName = 'Jones' AND FirstName = 'John')

• In a LIKE clause, you can use a wildcard at the beginning and end of the pattern (for example, LastName Like '*mit*'), or only at the end of the pattern (for example, LastName Like 'Smit*').

The filter constants make it easier to resolve individual record conflicts during batch update mode by allowing you to view, for example, only those records that were affected during the last UpdateBatch method call.

Setting the Filter property itself may fail because of a conflict with the underlying data (for example, a record has already been deleted by another user). In such a case, the provider returns warnings to the Errors collection but does not halt program execution. A run-time error occurs only if there are conflicts on all the requested records. Use the Status property to locate records with conflicts.

Setting the Filter property to a zero-length string ("") has the same effect as using the adFilterNone constant.

Whenever the Filter property is set, the current record position moves to the first record in the filtered subset of records in the Recordset. Similarly, when the Filter property is cleared, the current record position moves to the first record in the Recordset.

See the Bookmark property for an explanation of bookmark values from which you can build an array to use with the Filter property.