Re: [libsql] Query and QueryW

[<re...@du...>]

hi,

like to ask you again.. please download tortoisecvs (or some other cvs 
client), and tell me the name of your sourceforge account. cvs is so 
convenient for this, and i may make less errors merging..

Dak wrote:

>Hello Rene
>
>I have suggestion, how to regularize differences
>between Query and QueryW command in TLiteDB class. I
>suggest use in both metods next functions
>SQLite3_Prepare(16), SQLite3_Step and
>SQLite3_Finalize, because this way makes it possible
>returns more complex info about returned columns in
>ResultSet. I will place current implementation Query
>metod (with SQLite_exec function) for example in to
>new metod SimpleQuery or i dont use this anyway. I
>will changne this, that SimpleQuery return no
>resultset and be very simple. The final solution
>depends on you. In actual implementation of metods
>Query and QueryW is couple of missing thigs. If i want
>get content table (for exapmle SELECT * FROM Table1;)
>and table is full empty (has no row), both metods dont
>return name of columns. In DB browser i need show name
>of columns even if table is full empty too. Metod
>QueryW dont support execution of SQL multistatements.
>All this missing thigs i try solve in my proposal. My
>proposal looks like in this next metods, it is noly
>pseudo-code, full implementation depends on you, you
>know your code complex and in detail.
>
>function TLiteDB.SimpleQuery(SQL: String): Boolean;
>begin
>  use classic way with SQLite_exec. Maybe is possible
>completely leave out @QueryCallBack function. Then is
>possible use this function for speed execution of
>large, a lot of sql statements which dont need
>ResultSet.  
>end;
>
>function TLiteDB.Query(SQL: String): Boolean;
>var
>  SQLStatement: PAnsiChar;  
>  Stmt: Pointer;
>  sr,qr: Integer;
>  FLastError: Integer;
>begin
>  SQLStatement := PAnsiChar(SQL);
>  
>  repeat
>  
>    try
>      FLastError := SQLite3_prepare(FBaseInfo.FHandle,
>SQLStatement, -1, Stmt, SQLStatement);
>    
>      if FLastError = SQLite_OK then
>      begin
>        //This must be first, to get definition of
>columns even if table is include no rows 
>        //This one you execute very pretty in function
>StoreFields3, but this must be first!
>        if Not FieldDef then
>        begin
>          Columns := SQLite3_Column_count(Stmt);
>          for i := 0 to Columns - 1 do
>          begin
>            name := Sqlite3_Column_Name(Stmt, i);
>            _datatype := Sqlite3_Column_Type (Stmt,
>i);
>          end;
>        end;       
>        
>        sr := SQLite3_step (Stmt);
>        
>        while sr=SQLITE_BUSY do
>        begin
>          sleep(0);
>          sr := SQLite3_step (Stmt);
>        end;
>        
>        while sr=SQLITE_ROW do
>        begin
>          //Geting simple fields of current row
>          //This one you execute very pretty in
>function StoreRow3
>          Columns := SQLite3_Column_count(Stmt);
>          for i := 0 to Columns - 1 do
>          begin
>            Value := SQLite3_Column_Text(Stmt, i);
>          end;
>          sr := SQLite3_step(Stmt);
>          while sr=SQLITE_BUSY do
>          begin
>            sleep(0);
>            sr := SQLite3_step (Stmt);
>          end;
>        end;
>        
>        if sr in [SQLITE_ERROR, SQLITE_MISUSE] then
>          begin
>            FLastErrorText :=
>SQLite3_errormsg(FBaseInfo.FHandle);
>            FLastError :=
>SQLite3_errcode(FBaseInfo.FHandle);
>          end
>        else
>          begin
>            FLastErrorText := '';
>            FLastError := 0;
>          end;
>      end
>      else
>        FLastErrorText := SQLite3_errormsg
>(FBaseInfo.FHandle);
>        
>    finally
>      //I see this finalisation in others SQLite
>wrappers and works well
>      SQLite3_reset(Stmt); 
>      SQLite3_finalize(Stmt);
>    end;
>    
>  until SQLStatement^ = #0; //This one solve problem
>with SQL Multi-Statement
>    
>end;
>
>function TLiteDB.QueryW(SQL: WideString): Boolean;
>var
>  SQLStatement: PWideChar;  
>  Stmt: Pointer;
>  sr,qr: Integer;
>  FLastError: Integer;
>begin
>  SQLStatement := PAnsiChar(SQL);
>  
>  repeat
>  
>    try
>      FLastError :=
>SQLite3_prepare16(FBaseInfo.FHandle, SQLStatement, -1,
>Stmt, SQLStatement);
>    
>      if FLastError = SQLite_OK then
>      begin
>        //This must be first, to get definition of
>columns even if table is include no rows 
>        //This one you execute very pretty in function
>StoreFields3, but this must be first!
>        if Not FieldDef then
>        begin
>          Columns := SQLite3_Column_count(Stmt);
>          for i := 0 to Columns - 1 do
>          begin
>            name := Sqlite3_Column_Name16(Stmt, i);
>            _datatype := Sqlite3_Column_Type (Stmt,
>i);
>          end;
>        end;       
>        
>        sr := SQLite3_step (Stmt);
>        
>        while sr=SQLITE_BUSY do
>        begin
>          sleep(0);
>          sr := SQLite3_step (Stmt);
>        end;
>        
>        while sr=SQLITE_ROW do
>        begin
>          //Geting simple fields of current row
>          //This one you execute very pretty in
>function StoreRow3
>          Columns := SQLite3_Column_count(Stmt);
>          for i := 0 to Columns - 1 do
>          begin
>            Value := SQLite3_Column_Text16(Stmt, i);
>          end;
>          sr := SQLite3_step(Stmt);
>          while sr=SQLITE_BUSY do
>          begin
>            sleep(0);
>            sr := SQLite3_step (Stmt);
>          end;
>        end;
>        
>        if sr in [SQLITE_ERROR, SQLITE_MISUSE] then
>          begin
>            FLastErrorText :=
>SQLite3_errormsg16(FBaseInfo.FHandle);
>            FLastError :=
>SQLite3_errcode(FBaseInfo.FHandle);
>          end
>        else
>          begin
>            FLastErrorText := '';
>            FLastError := 0;
>          end;
>      end
>      else
>        FLastErrorText := SQLite3_errormsg16
>(FBaseInfo.FHandle);
>        
>    finally
>      //I see this finalisation in others SQLite
>wrappers and works well
>      SQLite3_reset(Stmt); 
>      SQLite3_finalize(Stmt);
>    end;
>    
>  until SQLStatement^ = #0; //This one solve problem
>with SQL Multi-Statement
>    
>end;
>
>Thanks my riend Flyman for his help with translation.
>
>Dak
>
>
>
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