Reimplement ANSI support to keep nutcases armed with v3.23 mysql servers happy.

Fixes issue #497.

components/zeosdbo/src/dbc/ZDbcMySql.pas

@@ -99,6 +99,7 @@ type
 
     function GetPlainDriver: IZMySQLPlainDriver;
     function GetConnectionHandle: PZMySQLConnect;
+    function GetAnsiMode: Boolean;
   end;
 
   {** Implements MySQL Database Connection. }
@@ -107,7 +108,7 @@ type
     FCatalog: string;
     FPlainDriver: IZMySQLPlainDriver;
     FHandle: PZMySQLConnect;
-    FClientCodePage: string;
+    FAnsiMode: Boolean;
   public
     constructor Create(Driver: IZDriver; const Url: string;
       PlainDriver: IZMySQLPlainDriver; const HostName: string; Port: Integer;
@@ -141,6 +142,7 @@ type
     function GetPlainDriver: IZMySQLPlainDriver;
     function GetConnectionHandle: PZMySQLConnect;
     function GetDescription: AnsiString;
+    function GetAnsiMode: Boolean;
   end;
 
 
@@ -358,9 +360,6 @@ begin
   AutoCommit := True;
   TransactIsolationLevel := tiNone;
 
-  { Processes connection properties. }
-  FClientCodePage := Trim(Info.Values['codepage']);
-
   Open;
 end;
 
@@ -438,10 +437,14 @@ begin
     end;
     DriverManager.LogMessage(lcConnect, FPlainDriver.GetProtocol, LogMessage);
 
+    FAnsiMode := FPlainDriver.GetServerVersion(FHandle) < 40100;
+
     { Sets a client codepage. }
+    if not FAnsiMode then begin
       FPlainDriver.SetCharacterSet(FHandle, 'utf8');
       CheckMySQLError(FPlainDriver, FHandle, lcExecute, LogMessage);
       DriverManager.LogMessage(lcExecute, FPlainDriver.GetProtocol, LogMessage);
+    end;
 
     { Sets transaction isolation level. }
     OldLevel := TransactIsolationLevel;
@@ -781,6 +784,11 @@ begin
     Result := self.FPlainDriver.GetDescription;
 end;
 
+function TZMySQLConnection.GetAnsiMode: Boolean;
+begin
+  Result := FAnsiMode;
+end;
+
 initialization
   MySQLDriver := TZMySQLDriver.Create;
   DriverManager.RegisterDriver(MySQLDriver);

components/zeosdbo/src/dbc/ZDbcMySqlResultSet.pas

@@ -269,7 +269,10 @@ begin
       //       thus the value returned below will always be 0.  Same goes for prepared
       //       statements, unless STMT_ATTR_UPDATE_MAX_LENGTH is specified.
       FieldWidthMax := FPlainDriver.GetFieldMaxLength(FieldHandle);
-      if FPlainDriver.GetFieldCollationId(FieldHandle) <> COLLATION_BINARY then begin
+      if
+        (FPlainDriver.GetFieldCollationId(FieldHandle) <> COLLATION_BINARY) and
+        (FPlainDriver.GetFieldCollationId(FieldHandle) <> COLLATION_NONE)
+      then begin
         // Results are always utf-8.  The MySQL utf-8 encoder can produce sequences that
         // consist of up to 3 bytes per character.  That's the number which the MySQL
         // C API will return when queried, since the server (and the driver) returns
@@ -419,7 +422,10 @@ end;
 
 function TZMySQLResultSet.GetUnicodeString(ColumnIndex: Integer): WideString;
 begin
-  Result := UTF8Decode(GetRawData(ColumnIndex));
+  if not ((Statement.GetConnection) as IZMySQLConnection).GetAnsiMode then
+    Result := UTF8Decode(GetRawData(ColumnIndex))
+  else
+    Result := WideString(GetRawData(ColumnIndex));
 end;
 
 {**

components/zeosdbo/src/dbc/ZDbcMySqlStatement.pas

@@ -177,9 +177,13 @@ end;
     given query; never <code>null</code>
 }
 function TZMySQLStatement.ExecuteQuery(const SQL: WideString): IZResultSet;
+var
+  nativeSql: string;
 begin
   Result := nil;
-  if FPlainDriver.ExecQuery(FHandle, PChar(UTF8Encode(SQL))) = 0 then
+  if not (Connection as IZMySQLConnection).GetAnsiMode then nativeSql := UTF8Encode(SQL)
+  else nativeSql := String(SQL);
+  if FPlainDriver.ExecQuery(FHandle, PChar(nativeSql)) = 0 then
   begin
     DriverManager.LogMessage(lcExecute, FPlainDriver.GetProtocol, SQL);
 {$IFDEF ENABLE_MYSQL_DEPRECATED}

components/zeosdbo/src/plain/ZPlainMySqlDriver.pas

@@ -153,6 +153,9 @@ const
   _CLIENT_REMEMBER_OPTIONS = 2147483648; {Enable/disable multi-results }
 
   COLLATION_BINARY = 63;
+  // Equivalent to COLLATION_BINARY, this is what
+  // a new driver returns when connected to a pre-4.1 server.
+  COLLATION_NONE   =  0;
 
 type
   PZMySQLConnect = Pointer;