freepascal 2.6
unit odbcconn;
function TODBCConnection.LoadField(cursor: TSQLCursor; FieldDef:
TFieldDef; buffer: pointer; out CreateBlob : boolean): boolean;
{$ELSE}
function TODBCConnection.LoadField(cursor: TSQLCursor; FieldDef:
TFieldDef; buffer: pointer):boolean;
{$ENDIF}
var
ODBCCursor:TODBCCursor;
StrLenOrInd:SQLINTEGER;
ODBCDateStruct:SQL_DATE_STRUCT;
ODBCTimeStruct:SQL_TIME_STRUCT;
ODBCTimeStampStruct:SQL_TIMESTAMP_STRUCT;
DateTime:TDateTime;
{$IF NOT((FPC_VERSION>=2) AND (FPC_RELEASE>=1))}
BlobBuffer:pointer;
BlobBufferSize,BytesRead:SQLINTEGER;
BlobMemoryStream:TMemoryStream;
{$ENDIF}
Res:SQLRETURN;
begin
{$IF (FPC_VERSION>=2) AND (FPC_RELEASE>=1)}
CreateBlob := False;
{$ENDIF}
ODBCCursor:=cursor as TODBCCursor;
// load the field using SQLGetData
// Note: optionally we can implement the use of SQLBindCol later for
even more speed
// TODO: finish this
case FieldDef.DataType of
ftWideString,ftFixedWideChar: // mapped to TWideStringField
Res:=SQLGetData(ODBCCursor.FSTMTHandle, FieldDef.Index+1,
SQL_C_WCHAR, buffer, FieldDef.Size+sizeof(WideChar), @StrLenOrInd);
//buffer must contain space for the null-termination character
ftGuid, ftFixedChar,ftString: // are mapped to a TStringField
(including TGuidField)
Res:=SQLGetData(ODBCCursor.FSTMTHandle, FieldDef.Index+1,
SQL_C_CHAR, buffer, FieldDef.Size+1, @StrLenOrInd);
ftSmallint: // mapped to TSmallintField
Res:=SQLGetData(ODBCCursor.FSTMTHandle, FieldDef.Index+1,
SQL_C_SSHORT, buffer, SizeOf(Smallint), @StrLenOrInd);
ftInteger,ftWord,ftAutoInc: // mapped to TLongintField
Res:=SQLGetData(ODBCCursor.FSTMTHandle, FieldDef.Index+1,
SQL_C_SLONG, buffer, SizeOf(Longint), @StrLenOrInd);
ftLargeint: // mapped to TLargeintField
Res:=SQLGetData(ODBCCursor.FSTMTHandle, FieldDef.Index+1,
SQL_C_SBIGINT, buffer, SizeOf(Largeint), @StrLenOrInd);
ftFloat: // mapped to TFloatField
Res:=SQLGetData(ODBCCursor.FSTMTHandle, FieldDef.Index+1,
SQL_C_DOUBLE, buffer, SizeOf(Double), @StrLenOrInd);
ftTime: // mapped to TTimeField
begin
Res:=SQLGetData(ODBCCursor.FSTMTHandle, FieldDef.Index+1,
SQL_C_TYPE_TIME, @ODBCTimeStruct, SizeOf(SQL_TIME_STRUCT), @StrLenOrInd);
if StrLenOrInd<>SQL_NULL_DATA then
begin
DateTime:=TimeStructToDateTime(@ODBCTimeStruct);
Move(DateTime, buffer^, SizeOf(TDateTime));
end;
end;
ftDate: // mapped to TDateField
begin
Res:=SQLGetData(ODBCCursor.FSTMTHandle, FieldDef.Index+1,
SQL_C_TYPE_DATE, @ODBCDateStruct, SizeOf(SQL_DATE_STRUCT), @StrLenOrInd);
if StrLenOrInd<>SQL_NULL_DATA then
begin
DateTime:=DateStructToDateTime(@ODBCDateStruct);
Move(DateTime, buffer^, SizeOf(TDateTime));
end;
end;
ftDateTime: // mapped to TDateTimeField
begin
// Seems like not all ODBC-drivers (mysql on Linux) set the
fractional part. Initialize
// it's value to avoid 'random' data.
ODBCTimeStampStruct.Fraction:=0;
Res:=SQLGetData(ODBCCursor.FSTMTHandle, FieldDef.Index+1,
SQL_C_TYPE_TIMESTAMP, @ODBCTimeStampStruct,
SizeOf(SQL_TIMESTAMP_STRUCT), @StrLenOrInd);
if StrLenOrInd<>SQL_NULL_DATA then
begin
DateTime:=TimeStampStructToDateTime(@ODBCTimeStampStruct);
Move(DateTime, buffer^, SizeOf(TDateTime));
end;
end;
ftBoolean: // mapped to TBooleanField
Res:=SQLGetData(ODBCCursor.FSTMTHandle, FieldDef.Index+1,
SQL_C_BIT, buffer, SizeOf(Wordbool), @StrLenOrInd);
ftBytes: // mapped to TBytesField
Res:=SQLGetData(ODBCCursor.FSTMTHandle, FieldDef.Index+1,
SQL_C_BINARY, buffer, FieldDef.Size, @StrLenOrInd);
ftVarBytes: // mapped to TVarBytesField
Res:=SQLGetData(ODBCCursor.FSTMTHandle, FieldDef.Index+1,
SQL_C_BINARY, buffer, FieldDef.Size, @StrLenOrInd);
{$IF (FPC_VERSION>=2) AND (FPC_RELEASE>=1)}
ftWideMemo,
{$ENDIF}
ftBlob, ftMemo: // BLOBs
begin
//Writeln('BLOB');
// Try to discover BLOB data length
Res:=SQLGetData(ODBCCursor.FSTMTHandle, FieldDef.Index+1,
SQL_C_BINARY, buffer, 0, @StrLenOrInd);
ODBCCheckResult(Res, SQL_HANDLE_STMT, ODBCCursor.FSTMTHandle,
'Could not get field data for field "%s" (index %d).',[FieldDef.Name,
FieldDef.Index+1]);
// Read the data if not NULL
if StrLenOrInd<>SQL_NULL_DATA then
begin
{$IF (FPC_VERSION>=2) AND (FPC_RELEASE>=1)}
CreateBlob:=true; // defer actual loading of blob data to
LoadBlobIntoBuffer method
//WriteLn('Deferring loading of blob of length ',StrLenOrInd);
{$ELSE}
// Determine size of buffer to use
if StrLenOrInd<>SQL_NO_TOTAL then
BlobBufferSize:=StrLenOrInd
else
BlobBufferSize:=DEFAULT_BLOB_BUFFER_SIZE;
try
// init BlobBuffer and BlobMemoryStream to nil pointers
BlobBuffer:=nil;
BlobMemoryStream:=nil;
if BlobBufferSize>0 then // Note: zero-length BLOB is
represented as nil pointer in the field buffer to save memory usage
begin
// Allocate the buffer and memorystream
BlobBuffer:=GetMem(BlobBufferSize);
BlobMemoryStream:=TMemoryStream.Create;
// Retrieve data in parts (or effectively in one part if
StrLenOrInd<>SQL_NO_TOTAL above)
repeat
Res:=SQLGetData(ODBCCursor.FSTMTHandle, FieldDef.Index+1,
SQL_C_BINARY, BlobBuffer, BlobBufferSize, @StrLenOrInd);
ODBCCheckResult(Res, SQL_HANDLE_STMT,
ODBCCursor.FSTMTHandle, 'Could not get field data for field "%s" (index
%d).',[FieldDef.Name, FieldDef.Index+1]);
// Append data in buffer to memorystream
if (StrLenOrInd=SQL_NO_TOTAL) or
(StrLenOrInd>BlobBufferSize) then
BytesRead:=BlobBufferSize
else
BytesRead:=StrLenOrInd;
BlobMemoryStream.Write(BlobBuffer^, BytesRead);
until Res=SQL_SUCCESS;
end;
// Store memorystream pointer in Field buffer and in the
cursor's FBlobStreams list
TObject(buffer^):=BlobMemoryStream;
if BlobMemoryStream<>nil then
ODBCCursor.FBlobStreams.Add(BlobMemoryStream);
// Set BlobMemoryStream to nil, so it won't get freed in the
finally block below
BlobMemoryStream:=nil;
finally
BlobMemoryStream.Free;
if BlobBuffer<>nil then
Freemem(BlobBuffer,BlobBufferSize);
end;
{$ENDIF}
end;
end;
// TODO: Loading of other field types
else
raise EODBCException.CreateFmt('Tried to load field of unsupported
field type %s',[Fieldtypenames[FieldDef.DataType]]);
end;
ODBCCheckResult(Res, SQL_HANDLE_STMT, ODBCCursor.FSTMTHandle, 'Could
not get field data for field "%s" (index %d).',[FieldDef.Name,
FieldDef.Index+1]);
Result:=StrLenOrInd<>SQL_NULL_DATA; // Result indicates whether the
value is non-null
//writeln(Format('Field.Size: %d; StrLenOrInd: %d',[FieldDef.Size,
StrLenOrInd]));
end;
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