error_design.md

#Error Our Mini SQL must contribute a complete Error Processing mechanism.I have made the Error class.When writing our MiniSQL, please use the error class. ##c++ review pleas review the syntax about exception.such as

try
{
	...
}
catch(..)
{
	...
}

##About class Error The class name is Error. ###throw an error if you want to throw an error, for example you think the user input a wrong table name, write code like this:

Error newerror(<errornumber>,"table name error");
throw newerror;

errornumber is the index in errorlist[], means the base type of the error, for example, table name error is a kind of "SQL syntax error". ###create a new error type if your error type is not in the error_list in error.cpp, you must add it in the error_list in error.cpp.It's the error_list now:

const std::string Error::error_list[]={
	"database storage failed",	//1
	"..."						//2
};

if your error is "SQL syntax error", then you can change the code to:

const std::string Error::error_list[]={
	"database storage failed",	//1
	"SQL syntax error"			//2
	"..."
};

###catch an error you don't need to catch the error everywhere, We would catch it in main function, but if you need to catch your error, just catch it.