:拼接SQL字符串的有关问题

求助:拼接SQL字符串的问题
用字符串拼接的SQL语句，比如:
"insert into table1 (UnitPrice,SumPrice) values("+UnitPrice+","+SumPrice+")"
UnitPrice,SumPrice是数值类型的变量，如果值为null，拼接时就会变成空字符串:
"insert into table1 UnitPrice,SumPrice values(,)"
这就导致语法错误，请问这该怎么处理？


------解决方案--------------------------------------------------------
string sql ="insert into table1 (UnitPrice,SumPrice) values("+UnitPrice??0+","+SumPrice??0+")";
------解决方案--------------------------------------------------------
string sql =string.Fromat("insert into table1 (UnitPrice,SumPrice) values('{0}','{1}')",UnitPrice??0,SumPrice??0);