timestamp_time : ULong;

  end;

  PISC_TIMESTAMP = ^ISC_TIMESTAMP;

implementation

...

procedure isc_encode_timestamp  (tm_date: PTM;

                                                            ib_date: PISC_TIMESTAMP);

                                stdcall; external IBASE_DLL;

procedure isc_decode_timestamp  (ib_date: PISC_TIMESTAMP;

                                 tm_date: PTM);

                                stdcall; external IBASE_DLL;

procedure isc_decode_sql_date   (var ib_date: Long;

                                 tm_date: PTM);

                                stdcall; external IBASE_DLL;

procedure isc_encode_sql_date   (tm_date: PTM;

                                 var ib_date: Long);

                                stdcall; external IBASE_DLL;

procedure isc_decode_sql_time   (var ib_date: ULong;

                                 tm_date: PTM);

                                stdcall; external IBASE_DLL;

procedure isc_encode_sql_time   (tm_date: PTM;

                                 var ib_date: ULong);

                                stdcall; external IBASE_DLL;

现在我们写日期UDF:

       在单元文件的interface部分，输入声明：

function Year(var ib_date: Long): Integer; cdecl; export;

function Hour(var ib_time: ULong): Integer; cdecl; export;

在implementation(实现)部分，输入：

function Year(var ib_date: Long): Integer;

var

  tm_date: TM;

begin

  isc_decode_sql_date(@ib_date, @tm_date);

  result := tm_date.tm_year + 1900;

end;

function Hour(var ib_time: ULong): Integer;

var

  tm_date: TM;

begin

  isc_decode_sql_time(@ib_time, @tm_date);

  result := tm_date.tm_hour;

end;

最好，在你的工程文件中：在““部分，输入：

exports

Modulo,

Left,

Year,

Hour;

现在编译工程...

为了使用这个函数，就像上面那样：用ISQL连接数据库，输入：

declare external function f_Year

date

returns integer by value

entry_point 'Year' module_name 'dll name minus ".dll"';

declare external function f_Hour

time

returns integer by value

entry_point 'Hour' module_name 'dll name minus ".dll"';

最后再测试一下看!

select f_Year(cast('7/11/00' as date)) from rdb$database

这一部分并非像前面字符串和整数那样操作哪样了，但是还是相当...simple,哼!

编写Linux/Unix平台的UDF

(未完待续!!)

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