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(*
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* Firebird UDR Support (fbudrtestbed). The fbudr components provide a set of
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* Pascal language bindings for the Firebird API in support of server
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* side User Defined Routines (UDRs). The fbudr package is an extension
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* to the Firebird Pascal API.
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*
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* The contents of this file are subject to the Initial Developer's
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* Public License Version 1.0 (the "License"); you may not use this
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* file except in compliance with the License. You may obtain a copy
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* of the License here:
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*
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* http://www.firebirdsql.org/index.php?op=doc&id=idpl
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*
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* Software distributed under the License is distributed on an "AS
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* IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
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* implied. See the License for the specific language governing rights
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* and limitations under the License.
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*
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* The Initial Developer of the Original Code is Tony Whyman.
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*
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* The Original Code is (C) 2021 Tony Whyman, MWA Software
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* (http://www.mwasoftware.co.uk).
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*
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* All Rights Reserved.
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*
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* Contributor(s): ______________________________________.
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*
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*)
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unit udr_test01;
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{$IFDEF MSWINDOWS}
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{$DEFINE WINDOWS}
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{$ENDIF}
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{$IFDEF FPC}
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{$mode delphi}
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{$codepage UTF8}
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{$interfaces COM}
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{$ENDIF}
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interface
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uses
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Classes, SysUtils, IB, FBUDRController, FBUDRIntf;
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{This unit provides the implementation of selected number of UDR functions used
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to test out various aspects of the TFBUDRFunction class. Note that each class is
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registered with the FBUDRController at initialization time.}
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type
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{ TMyRowCountFunction implements a simple User Defined Routine (UDR) Function.
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The DDL for this UDR is:
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create or alter function MyRowCount (
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table_name varchar(31)
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) returns integer
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external name 'fbudrtests!row_count'
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engine udr;
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It is called with a single parameter (the name of a table or view in the database.
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The function then runs a simple select query to determine the number of rows
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in the table and returns the row count.
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}
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{ TMyRowCountFunction }
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TMyRowCountFunction = class(TFBUDRFunction)
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public
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function Execute(context: IFBUDRExternalContext;
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ProcMetadata: IFBUDRProcMetadata;
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InputParams: IFBUDRInputParams;
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ResultSQLType: cardinal): variant; override;
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end;
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{UDR function with deliberate error. This has the same signature as above,
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but deliberately tries to invoke an OpenCursor with a null sql string.
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This is to demonstrate exception handling.
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create or alter function BadRowCount (
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table_name varchar(31)
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) returns integer
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external name 'fbudrtests!bad_row_count'
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engine udr;
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}
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{ TBadRowCountFunction }
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TBadRowCountFunction = class(TFBUDRFunction)
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public
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function Execute(context: IFBUDRExternalContext;
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ProcMetadata: IFBUDRProcMetadata;
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InputParams: IFBUDRInputParams;
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ResultSQLType: cardinal): variant; override;
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end;
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{TReturnInfoFunction implements a function that obtains and returns the info
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string from the external name. This is to demonstrate correct handling and
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parsing of the function entry point, as well as an empty input string.
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create or alter function UDRInfo (
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) returns VarChar(31)
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external name 'fbudrtests!return_info!Hello World'
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engine udr;
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}
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{ TReturnInfoFunction }
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TReturnInfoFunction = class(TFBUDRFunction)
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public
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function Execute(context: IFBUDRExternalContext;
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ProcMetadata: IFBUDRProcMetadata;
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InputParams: IFBUDRInputParams;
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ResultSQLType: cardinal): variant; override;
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end;
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implementation
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{ TReturnInfoFunction }
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function TReturnInfoFunction.Execute(context: IFBUDRExternalContext;
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ProcMetadata: IFBUDRProcMetadata; InputParams: IFBUDRInputParams;
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ResultSQLType: cardinal): variant;
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begin
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Result := ProcMetadata.getInfo;
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end;
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{ TBadRowCountFunction }
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function TBadRowCountFunction.Execute(context: IFBUDRExternalContext;
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ProcMetadata: IFBUDRProcMetadata; InputParams: IFBUDRInputParams;
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ResultSQLType: cardinal): variant;
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begin
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with context do
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begin
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Result := GetAttachment.OpenCursorAtStart(GetTransaction,'')[0].AsInteger;
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end;
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end;
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{ TMyRowCountFunction }
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function TMyRowCountFunction.Execute(context: IFBUDRExternalContext;
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ProcMetadata: IFBUDRProcMetadata; InputParams: IFBUDRInputParams;
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ResultSQLType: cardinal): variant;
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begin
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with context do
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begin
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Result := GetAttachment.OpenCursorAtStart(GetTransaction,
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'Select count(*) from ' + InputParams.ByName('table_name').AsString)[0].AsInteger;
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end;
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end;
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Initialization
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FBRegisterUDRFunction('row_count',TMyRowCountFunction);
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FBRegisterUDRFunction('bad_row_count',TBadRowCountFunction);
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FBRegisterUDRFunction('return_info',TReturnInfoFunction);
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end.
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|
