locate

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Definition

Unit: FreePascal, unit db

    function  Locate(const KeyFields: string; const KeyValues: Variant; Options: TLocateOptions): Boolean; override;

Official documentation: none

Description

locate looks for a record in the dataset where the specified search values for the specified fields match. If found, the function returns true and the cursor position/current record moves to that record.

KeyFields can be a single field name or a semicolon-separated list of fields.

KeyValue can be a variant or a variant array and the number of items must match the number of fields specified in KeyFields.

Search options can be

  • loCaseInsensitive: ignore upper case/lower case differences when searching
  • loPartialKey: match partial finds (instead of the complete key). Note: this only works for string-type fields, not for number/date/currency etc fields where this option is ignored.
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Note: Locate is only implemented in non-unidirectional datasets, i.e. you must be able to move back and forwards through the dataset.

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Note: Locate and lookup act at low level inside a dataset to search for records. Often it is more efficient to filter/limit what gets into the dataset in the first place, e.g. using SQL WHERE clauses.

Examples

Using a TDBF dataset and looking for 'di Angelo', 'Di Angelo' etc in a field called LASTNAME:

uses dbf, db
...
if MyDBF.Locate('LASTNAME','di Angelo',[loCaseInsensitive])then
  writeln('Found record.');


Using multiple fields to find a record.

Note: you have to add Variants to the uses clause.

uses Variants;
..
procedure LocateMyRecord;
var
  aCityID, aCountryID: integer;
begin
  if Locate('city_id;country_id', VarArrayOf([aCityID, aCountryID]), []) then
  begin
    DoSomething;
  end;
end;

See also

  • lookup
  • [1] Description of how to use locate with Delphi