fpc/fcl/db/sqldb/sqldb.pp

{   $Id$

    Copyright (c) 2004 by Joost van der Sluis


    SQL database & dataset

    See the file COPYING.FPC, included in this distribution,
    for details about the copyright.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

 **********************************************************************}

unit sqldb;

{$mode objfpc}
{$H+}
{$M+}   // ### remove this!!!

interface

uses SysUtils, Classes, DB;

type TSchemaType = (stNoSchema, stTables, stSysTables, stProcedures, stColumns, stProcedureParams, stIndexes, stPackages);

type
  TSQLConnection = class;
  TSQLTransaction = class;
  TSQLQuery = class;

  TStatementType = (stNone, stSelect, stInsert, stUpdate, stDelete,
    stDDL, stGetSegment, stPutSegment, stExecProcedure,
    stStartTrans, stCommit, stRollback, stSelectForUpd);

  TSQLHandle = Class(TObject)
    protected
    StatementType       : TStatementType;
  end;


const
 StatementTokens : Array[TStatementType] of string = ('(none)', 'select',
                  'insert', 'update', 'delete',
                  'create', 'get', 'put', 'execute',
                  'start','commit','rollback', '?'
                 );


{ TSQLConnection }
type
  TSQLConnection = class (TDatabase)
  private
    FPassword            : string;
    FTransaction         : TSQLTransaction;
    FUserName            : string;
    FHostName            : string;
    FCharSet             : string;
    FRole                : String;

    procedure SetTransaction(Value : TSQLTransaction);
  protected
    function StrToStatementType(s : string) : TStatementType; virtual;
    procedure DoInternalConnect; override;
    procedure DoInternalDisconnect; override;
    function GetAsSQLText(Field : TField) : string; virtual;
    function GetHandle : pointer; virtual; abstract;

    Function AllocateCursorHandle : TSQLHandle; virtual; abstract;
    Function AllocateTransactionHandle : TSQLHandle; virtual; abstract;

    procedure FreeStatement(cursor : TSQLHandle); virtual; abstract;
    procedure PrepareStatement(cursor: TSQLHandle;ATransaction : TSQLTransaction;buf : string); virtual; abstract;
    procedure FreeFldBuffers(cursor : TSQLHandle); virtual; abstract;
    procedure Execute(cursor: TSQLHandle;atransaction:tSQLtransaction); virtual; abstract;
    procedure AddFieldDefs(cursor: TSQLHandle; FieldDefs : TfieldDefs); virtual; abstract;
    function Fetch(cursor : TSQLHandle) : boolean; virtual; abstract;
    function LoadField(cursor : TSQLHandle;FieldDef : TfieldDef;buffer : pointer) : boolean; virtual; abstract;
    function GetTransactionHandle(trans : TSQLHandle): pointer; virtual; abstract;
    function Commit(trans : TSQLHandle) : boolean; virtual; abstract;
    function RollBack(trans : TSQLHandle) : boolean; virtual; abstract;
    function StartdbTransaction(trans : TSQLHandle) : boolean; virtual; abstract;
    procedure CommitRetaining(trans : TSQLHandle); virtual; abstract;
    procedure RollBackRetaining(trans : TSQLHandle); virtual; abstract;
    procedure UpdateIndexDefs(var IndexDefs : TIndexDefs;TableName : string); virtual;
    function GetSchemaInfoSQL(SchemaType : TSchemaType; SchemaObjectName, SchemaPattern : string) : string; virtual;
    function CreateBlobStream(Field: TField; Mode: TBlobStreamMode): TStream; virtual;abstract;
  public
    property Handle: Pointer read GetHandle;
    destructor Destroy; override;
  published
    property Password : string read FPassword write FPassword;
    property Transaction : TSQLTransaction read FTransaction write SetTransaction;
    property UserName : string read FUserName write FUserName;
    property CharSet : string read FCharSet write FCharSet;
    property HostName : string Read FHostName Write FHostName;

    property Connected;
    Property Role :  String read FRole write FRole;
    property DatabaseName;
    property KeepConnection;
    property LoginPrompt;
    property Params;
    property OnLogin;
  end;

{ TSQLTransaction }

  TCommitRollbackAction = (caNone, caCommit, caCommitRetaining, caRollback,
    caRollbackRetaining);

  TSQLTransaction = class (TDBTransaction)
  private
    FTrans               : TSQLHandle;
    FAction              : TCommitRollbackAction;
  protected
    function GetHandle : Pointer; virtual;
  public
    procedure Commit; virtual;
    procedure CommitRetaining; virtual;
    procedure Rollback; virtual;
    procedure RollbackRetaining; virtual;
    procedure StartTransaction; override;
    constructor Create(AOwner : TComponent); override;
    destructor Destroy; override;
    property Handle: Pointer read GetHandle;
    procedure EndTransaction; override;
  published
    property Action : TCommitRollbackAction read FAction write FAction;
    property Database;
  end;

{ TSQLQuery }

  TSQLQuery = class (Tbufdataset)
  private
    FCursor              : TSQLHandle;
    FUpdateable          : boolean;
    FTableName           : string;
    FSQL                 : TStrings;
    FIsEOF               : boolean;
    FLoadingFieldDefs    : boolean;
    FIndexDefs           : TIndexDefs;
    FReadOnly            : boolean;
    FUpdateMode          : TUpdateMode;
    FusePrimaryKeyAsKey  : Boolean;
//    FSchemaInfo          : TSchemaInfo;

    procedure FreeStatement;
    procedure PrepareStatement;
    procedure FreeFldBuffers;
    procedure InitUpdates(SQL : string);
    function GetIndexDefs : TIndexDefs;
    procedure SetIndexDefs(AValue : TIndexDefs);
    procedure SetReadOnly(AValue : Boolean);
    procedure SetUsePrimaryKeyAsKey(AValue : Boolean);
    procedure SetUpdateMode(AValue : TUpdateMode);

    procedure Execute;

  protected
    // abstract & virtual methods of TBufDataset
    function Fetch : boolean; override;
    function LoadField(FieldDef : TFieldDef;buffer : pointer) : boolean; override;
    // abstract & virtual methods of TDataset
    procedure UpdateIndexDefs; override;
    procedure SetDatabase(Value : TDatabase); override;
    procedure InternalAddRecord(Buffer: Pointer; AAppend: Boolean); override;
    procedure InternalClose; override;
    procedure InternalHandleException; override;
    procedure InternalInitFieldDefs; override;
    procedure InternalOpen; override;
    function  GetCanModify: Boolean; override;
    Function GetSQLStatementType(SQL : String) : TStatementType; virtual;
    function ApplyRecUpdate(UpdateKind : TUpdateKind) : boolean; override;
  public
    procedure ExecSQL; virtual;
    constructor Create(AOwner : TComponent); override;
    destructor Destroy; override;
    procedure SetSchemaInfo( SchemaType : TSchemaType; SchemaObjectName, SchemaPattern : string); virtual;
    function CreateBlobStream(Field: TField; Mode: TBlobStreamMode): TStream; override;
  published
    // redeclared data set properties
    property Active;
//    property Filter;
//    property Filtered;
//    property FilterOptions;
    property BeforeOpen;
    property AfterOpen;
    property BeforeClose;
    property AfterClose;
    property BeforeInsert;
    property AfterInsert;
    property BeforeEdit;
    property AfterEdit;
    property BeforePost;
    property AfterPost;
    property BeforeCancel;
    property AfterCancel;
    property BeforeDelete;
    property AfterDelete;
    property BeforeScroll;
    property AfterScroll;
    property OnCalcFields;
    property OnDeleteError;
    property OnEditError;
    property OnFilterRecord;
    property OnNewRecord;
    property OnPostError;
    property AutoCalcFields;
    property Database;

    property Transaction;
    property ReadOnly : Boolean read FReadOnly write SetReadOnly;
    property SQL : TStrings read FSQL write FSQL;
    property IndexDefs : TIndexDefs read GetIndexDefs;
    property UpdateMode : TUpdateMode read FUpdateMode write SetUpdateMode;
    property UsePrimaryKeyAsKey : boolean read FUsePrimaryKeyAsKey write SetUsePrimaryKeyAsKey;
//    property SchemaInfo : TSchemaInfo read FSchemaInfo default stNoSchema;
  end;

implementation

uses dbconst;

{ TSQLConnection }

function TSQLConnection.StrToStatementType(s : string) : TStatementType;

var T : TStatementType;

begin
  S:=Lowercase(s);
  For t:=stselect to strollback do
    if (S=StatementTokens[t]) then
      Exit(t);
end;

procedure TSQLConnection.SetTransaction(Value : TSQLTransaction);
begin
  if FTransaction = nil then
  begin
    FTransaction := Value;
    if Assigned(FTransaction) then
      FTransaction.Database := Self;
    exit;
  end;

  if (Value <> FTransaction) and (Value <> nil) then
    if (not FTransaction.Active) then
    begin
      FTransaction := Value;
      FTransaction.Database := Self;
    end
    else
      DatabaseError(SErrAssTransaction);
end;

procedure TSQLConnection.UpdateIndexDefs(var IndexDefs : TIndexDefs;TableName : string);

begin
// Empty abstract
end;

procedure TSQLConnection.DoInternalConnect;
begin
// Empty abstract
end;

procedure TSQLConnection.DoInternalDisconnect;
begin
end;

destructor TSQLConnection.Destroy;
begin
  inherited Destroy;
end;

function TSQLConnection.GetAsSQLText(Field : TField) : string;

begin
  if not assigned(field) then Result := 'Null'
  else case field.DataType of
    ftString   : Result := '''' + field.asstring + '''';
    ftDate     : Result := '''' + FormatDateTime('yyyy-mm-dd',Field.AsDateTime) + '''';
    ftDateTime : Result := '''' + FormatDateTime('yyyy-mm-dd hh:mm:ss',Field.AsDateTime) + ''''
  else
    Result := field.asstring;
  end; {case}
end;


function TSQLConnection.GetSchemaInfoSQL( SchemaType : TSchemaType; SchemaObjectName, SchemaPattern : string) : string;

begin
  DatabaseError(SMetadataUnavailable);
end;


{ TSQLTransaction }
procedure TSQLTransaction.EndTransaction;

begin
  rollback;
end;

function TSQLTransaction.GetHandle: pointer;
begin
  Result := (Database as tsqlconnection).GetTransactionHandle(FTrans);
end;

procedure TSQLTransaction.Commit;
begin
  if active then
    begin
    closedatasets;
    if (Database as tsqlconnection).commit(FTrans) then
      begin
      closeTrans;
      FreeAndNil(FTrans);
      end;
    end;
end;

procedure TSQLTransaction.CommitRetaining;
begin
  if active then
    (Database as tsqlconnection).commitRetaining(FTrans);
end;

procedure TSQLTransaction.Rollback;
begin
  if active then
    begin
    closedatasets;
    if (Database as tsqlconnection).RollBack(FTrans) then
      begin
      CloseTrans;
      FreeAndNil(FTrans);
      end;
    end;
end;

procedure TSQLTransaction.RollbackRetaining;
begin
  if active then
    (Database as tsqlconnection).RollBackRetaining(FTrans);
end;

procedure TSQLTransaction.StartTransaction;

var db : TSQLConnection;

begin
  if Active then
    DatabaseError(SErrTransAlreadyActive);

  db := (Database as tsqlconnection);

  if Db = nil then
    DatabaseError(SErrDatabasenAssigned);

  if not Db.Connected then
    Db.Open;
  if not assigned(FTrans) then FTrans := Db.AllocateTransactionHandle;

  if Db.StartdbTransaction(FTrans) then OpenTrans;
end;

constructor TSQLTransaction.Create(AOwner : TComponent);
begin
  inherited Create(AOwner);
end;

destructor TSQLTransaction.Destroy;
begin
  Rollback;
  inherited Destroy;
end;

{ TSQLQuery }
procedure TSQLQuery.SetDatabase(Value : TDatabase);

var db : tsqlconnection;

begin
  if (Database <> Value) then
    begin
    db := value as tsqlconnection;
    inherited setdatabase(value);
    if assigned(value) and (Transaction = nil) and (Assigned(db.Transaction)) then
      transaction := Db.Transaction;
    end;
end;

procedure TSQLQuery.FreeStatement;
begin
  if assigned(FCursor) then
    begin
    (Database as tsqlconnection).FreeStatement(FCursor);
//    FreeAndNil(FCursor);
    end;
end;

procedure TSQLQuery.PrepareStatement;
var
  Buf   : string;
  x     : integer;
  db    : tsqlconnection;
  sqltr : tsqltransaction;

begin
  db := (Database as tsqlconnection);
  if not assigned(Db) then
    DatabaseError(SErrDatabasenAssigned);
  if not Db.Connected then
    db.Open;
  if not assigned(Transaction) then
    DatabaseError(SErrTransactionnSet);

  sqltr := (transaction as tsqltransaction);
  if not sqltr.Active then sqltr.StartTransaction;

  if assigned(fcursor) then FreeAndNil(fcursor);
  FCursor := Db.AllocateCursorHandle;

  Buf := '';
  for x := 0 to FSQL.Count - 1 do
    Buf := Buf + FSQL[x] + ' '#10;  // multiline SQl. Provides line info in sqlErrors and allows single line comments

  if Buf='' then
    begin
    DatabaseError(SErrNoStatement);
    exit;
    end;
  FCursor.StatementType := GetSQLStatementType(buf);
  if (FCursor.StatementType = stSelect) and not ReadOnly then InitUpdates(Buf);
  Db.PrepareStatement(Fcursor,sqltr,buf);
end;

procedure TSQLQuery.FreeFldBuffers;
begin
  if assigned(FCursor) then (Database as tsqlconnection).FreeFldBuffers(FCursor);
end;

function TSQLQuery.Fetch : boolean;
begin
  if not (Fcursor.StatementType in [stSelect]) then
    Exit;

  if not FIsEof then FIsEOF := not (Database as tsqlconnection).Fetch(Fcursor);
  Result := not FIsEOF;
end;

procedure TSQLQuery.Execute;
begin
  (Database as tsqlconnection).execute(Fcursor,Transaction as tsqltransaction);
end;

function TSQLQuery.LoadField(FieldDef : TFieldDef;buffer : pointer) : boolean;

begin
  result := (Database as tSQLConnection).LoadField(FCursor,FieldDef,buffer)
end;

procedure TSQLQuery.InternalAddRecord(Buffer: Pointer; AAppend: Boolean);
begin
  // not implemented - sql dataset
end;

procedure TSQLQuery.InternalClose;
begin
  FreeFldBuffers;
  FreeStatement;
  if DefaultFields then
    DestroyFields;
  FIsEOF := False;
//  FRecordSize := 0;
  inherited internalclose;
end;

procedure TSQLQuery.InternalHandleException;
begin
end;

procedure TSQLQuery.InternalInitFieldDefs;
begin
  if FLoadingFieldDefs then
    Exit;

  FLoadingFieldDefs := True;

  try
    FieldDefs.Clear;

    (Database as tsqlconnection).AddFieldDefs(fcursor,FieldDefs);
  finally
    FLoadingFieldDefs := False;
  end;
end;

procedure TSQLQuery.InitUpdates(SQL : string);

Var
  L       : Integer;
  P,PP    : PChar;
  PS: PChar;
  S       : string;

  function GetStatement(var StartP : PChar) : PChar;

  var p        : pchar;
      Cmt, Stm : boolean;

  begin
    p := StartP;
    Cmt := false;
    Stm := False;
    While ((P-PP)<L) do
      begin
      if Cmt then
        begin
        end
      else if (p^ in [',',' ','(',')',#13,#10,#9]) then
        begin
        if stm then break;
        end
      else if not stm then
        begin
        StartP := p;
        stm := true;
        end;
      inc(p);
      end;
    Result := P;
  end;

begin
  FUpdateable := False;

  L:=Length(SQL);

  PP:=Pchar(SQL);
  P := pp;
  PS := pp;

// select-keyword
  P := GetStatement(PS);

  Setlength(S,P-PS);
  Move(PS^,S[1],(P-PS));
  S:=Lowercase(S);

  if (S) <> 'select' then exit;

// select-part

  While ((P-PP)<L) and  (S <> 'from') do
    begin
    repeat
    PS := P;
    P := GetStatement(PS);
    until P^ <> ',';

    Setlength(S,P-PS);
    Move(PS^,S[1],(P-PS));
    S:=Lowercase(S);

    end;

// from-part

  PS := P;
  P := GetStatement(PS);

  Setlength(FTableName,P-PS);
  Move(PS^,FTableName[1],(P-PS));

  While ((P-PP)<L)  do
    begin
    PS := P;
    P := GetStatement(PS);

    if P^ = ',' then exit; // select-statements from more then one table are not updateable

    Setlength(S,P-PS);
    Move(PS^,S[1],(P-PS));
    S:=Lowercase(S);

    if (s = 'where') or (s='order') then break;
    end;

  FUpdateable := True;
end;

procedure TSQLQuery.InternalOpen;

var tel : integer;
    f   : TField;
s : string;
begin
  try
    PrepareStatement;
    if Fcursor.StatementType in [stSelect] then
      begin
      Execute;
      InternalInitFieldDefs;
      if DefaultFields then
        begin
        CreateFields;

        if FUpdateable and FusePrimaryKeyAsKey then
          begin
          UpdateIndexDefs;
          for tel := 0 to indexdefs.count-1 do {with indexdefs[tel] do}
            begin
            if ixPrimary in indexdefs[tel].options then
              begin
              // Todo: If there is more then one field in the key, that must be parsed
                s := indexdefs[tel].fields;
                F := Findfield(s);
                if F <> nil then
                  F.ProviderFlags := F.ProviderFlags + [pfInKey];
              end;
            end;
          end;
        end;
      end
    else
      DatabaseError(SErrNoSelectStatement,Self);
  except
    on E:Exception do
      raise;
  end;
  inherited InternalOpen;
end;

// public part

procedure TSQLQuery.ExecSQL;
begin
  try
    PrepareStatement;
    Execute;
  finally
    FreeStatement;
  end;
end;

constructor TSQLQuery.Create(AOwner : TComponent);
begin
  inherited Create(AOwner);
  FSQL := TStringList.Create;
  FIndexDefs := TIndexDefs.Create(Self);
  FReadOnly := false;
// Delphi has upWhereAll as default, but since strings and oldvalue's don't work yet
// (variants) set it to upWhereKeyOnly
  FUpdateMode := upWhereKeyOnly;

  FUsePrimaryKeyAsKey := True;
end;

destructor TSQLQuery.Destroy;
begin
  if Active then Close;
//  if assigned(FCursor) then FCursor.destroy;
  FreeAndNil(FSQL);
  inherited Destroy;
end;

Function TSQLQuery.GetSQLStatementType(SQL : String) : TStatementType;

Var
  L       : Integer;
  cmt     : boolean;
  P,PE,PP : PChar;
  S       : string;

begin
  Result:=stNone;
  L:=Length(SQL);
  If (L=0) then
    Exit;
  P:=Pchar(SQL);
  PP:=P;
  Cmt:=False;
  While ((P-PP)<L) do
    begin
    if not (P^ in [' ',#13,#10,#9]) then
      begin
      if not Cmt then
        begin
        // Check for comment.
        Cmt:=(P^='/') and (((P-PP)<=L) and (P[1]='*'));
        if not (cmt) then
          Break;
        end
      else
        begin
        // Check for end of comment.
         Cmt:=Not( (P^='*') and (((P-PP)<=L) and (P[1]='/')) );
        If not cmt then
          Inc(p);
        end;
      end;
    inc(P);
    end;
  PE:=P+1;
  While ((PE-PP)<L) and (PE^ in ['0'..'9','a'..'z','A'..'Z','_']) do
   Inc(PE);
  Setlength(S,PE-P);
  Move(P^,S[1],(PE-P));
  result := (DataBase as TSQLConnection).StrToStatementType(s);
end;

procedure TSQLQuery.SetReadOnly(AValue : Boolean);

begin
  if not Active then FReadOnly := AValue
  else
    begin
    // Just temporary, this should be possible in the future
    DatabaseError(SActiveDataset);
    end;
end;

procedure TSQLQuery.SetUsePrimaryKeyAsKey(AValue : Boolean);

begin
  if not Active then FusePrimaryKeyAsKey := AValue
  else
    begin
    // Just temporary, this should be possible in the future
    DatabaseError(SActiveDataset);
    end;
end;

Procedure TSQLQuery.UpdateIndexDefs;

begin
  if assigned(DataBase) then
    (DataBase as TSQLConnection).UpdateIndexDefs(FIndexDefs,FTableName);
end;

function TSQLQuery.ApplyRecUpdate(UpdateKind : TUpdateKind) : boolean;

var
    sql_tables : string;
    s : string;

  procedure UpdateWherePart(var sql_where : string;x : integer);

  begin
    if (pfInKey in Fields[x].ProviderFlags) or
       ((FUpdateMode = upWhereAll) and (pfInWhere in Fields[x].ProviderFlags)) or
       ((FUpdateMode = UpWhereChanged) and (pfInWhere in Fields[x].ProviderFlags) and (fields[x].value <> fields[x].oldvalue)) then
      begin
      // This should be converted to something like GetAsSQLText, but better wait until variants (oldvalue) are working for strings
      s := fields[x].oldvalue; // This directly int the line below raises a variant-error
      sql_where := sql_where + '(' + fields[x].FieldName + '=' + s + ') and ';
      end;
  end;

  function ModifyRecQuery : string;

  var x          : integer;
      sql_set    : string;
      sql_where  : string;

  begin
    sql_tables := FTableName;
    sql_set := '';
    sql_where := '';
    for x := 0 to Fields.Count -1 do
      begin
      UpdateWherePart(sql_where,x);

      if (pfInUpdate in Fields[x].ProviderFlags) then
        if fields[x].IsNull then // check for null
          sql_set := sql_set + fields[x].FieldName + '=' + (Database as TSQLConnection).GetAsSQLText(nil) + ','
        else
          sql_set := sql_set + fields[x].FieldName + '=' + (Database as TSQLConnection).GetAsSQLText(fields[x]) + ',';
      end;

    setlength(sql_set,length(sql_set)-1);
    setlength(sql_where,length(sql_where)-5);
    result := 'update ' + sql_tables + ' set ' + sql_set + ' where ' + sql_where;

  end;

  function InsertRecQuery : string;

  var x          : integer;
      sql_fields : string;
      sql_values : string;

  begin
    sql_tables := FTableName;
    sql_fields := '';
    sql_values := '';
    for x := 0 to Fields.Count -1 do
      begin
      if not fields[x].IsNull then
        begin
        sql_fields := sql_fields + fields[x].DisplayName + ',';
        sql_values := sql_values + (Database as TSQLConnection).GetAsSQLText(fields[x]) + ',';
        end;
      end;
    setlength(sql_fields,length(sql_fields)-1);
    setlength(sql_values,length(sql_values)-1);

    result := 'insert into ' + sql_tables + ' (' + sql_fields + ') values (' + sql_values + ')';
  end;

  function DeleteRecQuery : string;

  var x          : integer;
      sql_where  : string;

  begin
    sql_tables := FTableName;

    sql_where := '';
    for x := 0 to Fields.Count -1 do
      UpdateWherePart(sql_where,x);

    setlength(sql_where,length(sql_where)-5);

    result := 'delete from ' + sql_tables + ' where ' + sql_where;
  end;

begin
  Result := False;
  with tsqlquery.Create(nil) do
    begin
    DataBase := self.Database;
    transaction := self.transaction;
    sql.clear;
    case UpdateKind of
      ukModify : s := ModifyRecQuery;
      ukInsert : s := InsertRecQuery;
      ukDelete : s := DeleteRecQuery;
    end; {case}
    sql.add(s);
    ExecSQL;
    Result := true;
    Free;
    end;
end;


Function TSQLQuery.GetCanModify: Boolean;

begin
  if FCursor.StatementType = stSelect then
    Result:= Active and  FUpdateable and (not FReadOnly)
  else
    Result := False;
end;

function TSQLQuery.GetIndexDefs : TIndexDefs;

begin
  Result := FIndexDefs;
end;

procedure TSQLQuery.SetIndexDefs(AValue : TIndexDefs);

begin
  FIndexDefs := AValue;
end;

procedure TSQLQuery.SetUpdateMode(AValue : TUpdateMode);

begin
  FUpdateMode := AValue;
end;

procedure TSQLQuery.SetSchemaInfo( SchemaType : TSchemaType; SchemaObjectName, SchemaPattern : string);

begin
  SQL.Clear;
  SQL.Add((DataBase as tsqlconnection).GetSchemaInfoSQL(SchemaType, SchemaObjectName, SchemaPattern));
end;


function TSQLQuery.CreateBlobStream(Field: TField; Mode: TBlobStreamMode): TStream;
begin
  result := (DataBase as tsqlconnection).CreateBlobStream(Field, Mode);
end;

end.

{
  $Log$
  Revision 1.15  2005-03-23 08:17:51  michael
  + Several patches from Jose A. Rimon
  # Prevents "field not found" error, when use a query without the primary key
  Set SQLlen of different data types
   Use AliasName instead of SQLname to avoid "duplicate field name" error, for
  example when using "coalesce" more than once
  use SQLScale in ftLargeInt to get actual values
   Send query to server with different lines. Provides line info in sqlErrors
  and allows single line comments

  Revision 1.14  2005/02/14 17:13:12  peter
    * truncate log

  Revision 1.13  2005/02/07 11:23:41  joost
    - implemented TSQLQuery.SetSchemaInfo
    - added support for delete and insert

  Revision 1.12  2005/01/24 10:52:43  michael
    * Patch from Joost van der Sluis
    - Made it possible to run 'show' queries for MySQL

  Revision 1.11  2005/01/12 10:30:33  michael
   * Patch from Joost Van der Sluis:
     - implemented TSQLQuery.UpdateIndexDefs
     - implemented TSQLQuery.ReadOnly
     - implemented TSQLQuery.IndexDefs
     - implemented TSQLQuery.UpdateMode
     - implemented TSQLQuery.UsePrimaryKeyAsKey (Set pfInKey in the
       providerflags
       of fields that are in the primary index of the underlying table)
     - Added support for updates on date-fields

}