Check connections to MySQL only if query execution fails

* Try to execute query using the existing connection.
* If that fails, establish new connection and execute query, so a
  balance is maintained between persistent connection and new connection
  for every query.
* If possible, look for a better/alternative solution.

external/info.lua

@@ -31,11 +31,13 @@ _G.tFunction = {
 
 	Execute = function( sQuery )
 		local luasql = luasql or require "luasql.mysql"
-		if not ( SQLEnv and SQLCon ) then
+		local bSuccess, SQLCur = pcall( SQLCon.execute, SQLCon, sQuery )
+		if not bSuccess then
 			_G.SQLEnv = assert( luasql.mysql() )
 			_G.SQLCon = assert( SQLEnv:connect(Connection 'latest') )
+			SQLCur = assert( SQLCon:execute(sQuery) )
 		end
-		return assert( SQLCon:execute(sQuery) )
+		return SQLCur
 	end,
 
 	Report = ( function()

external/offliner.lua

@@ -32,11 +32,13 @@ _G.tFunction = {
 
 	Execute = function( sQuery )
 		local luasql = luasql or require "luasql.mysql"
-		if not ( SQLEnv and SQLCon ) then
+		local bSuccess, SQLCur = pcall( SQLCon.execute, SQLCon, sQuery )
+		if not bSuccess then
 			_G.SQLEnv = assert( luasql.mysql() )
 			_G.SQLCon = assert( SQLEnv:connect(Connection 'latest') )
+			SQLCur = assert( SQLCon:execute(sQuery) )
 		end
-		return assert( SQLCon:execute(sQuery) )
+		return SQLCur
 	end,
 
 	Report = ( function()