VBScript RegExp不够贪婪

Question

我正在尝试编写一个简单的SQL解析器来将sql语句分解为其基本部分.但是,我遇到嵌套查询的问题.一个例子说明最好的:

sql = "select * from Customers where id in (select customer_id from Orders where 1=1)"
Set re = New RegExp
re.IgnoreCase = True
re.Pattern = "^(.*)\swhere\s(.*)$"
re.Global = True
Set matches = re.Execute( sql )


If matches.count > 0 Then
    Set submatches = matches(0).Submatches
    where_part = Trim(submatches(1))
    everything_else = Trim(submatches(0)) 
End If 

Response.Write where_part & "<br>"
Response.Write everything_else & "<br>"

在这里,我希望where_part包含"id in(从订单中选择customer_id,其中1 = 1)"和everything_else包含"select*from Customers".也就是说,我希望它尽可能地贪婪,第二个(.*)和第一个无私.换句话说,我希望everything_else不包含任何地方.

但是,我得到everything_else ="select*from customer in id in(select order_id from Orders"and where_part ="1 = 1)"

如何在不诉诸凌乱的非regexp字符串解析的情况下解决这个问题？

Answer 1

相反,你的正则表达式太贪婪了.

.*捕获最长的匹配字符串,直到您的示例中的第二个字符串.

试试这个:

^(.*?)\swhere\s(.*)

的？使.*表现得不那么贪婪,这意味着它会在第一次发生时停止.