如何访问循环外的变量?下面的代码似乎不起作用,变量是空的。
var userID;
foreach(var row in db.Query("SELECT ProviderUserId FROM webpages_OAuthMembership WHERE UserID = @0", currentUserId))
{
userID = row.ProviderUserId;
}
var userID1 = userID;
答案 0 :(得分:2)
您希望从哪个迭代中获取值?首先?最后?如果没有结果会怎么样?
LINQ可能是一种更简单的方法:
string sql = "SELECT ProviderUserId FROM webpages_OAuthMembership WHERE UserID = @0";
var userId = db.Query(sql, currentUserId)
.Select(x => x.ProviderUserId)
.SingleOrDefault();
if (userId != null)
{
...
}
(当然,如果ProviderUserId
不是某种类型的可空类型,那将无法正常工作,但我们目前并没有太多信息......)
答案 1 :(得分:0)
你的foreach循环返回IEnumerable
集合
var userID;
foreach(var row in db.Query("SELECT ProviderUserId FROM webpages_OAuthMembership WHERE UserID = @0", currentUserId))
{
userID = row.ProviderUserId;
}
var userID1 = userID;
持有userID
你可以这样做
List<string> userIDs = new List<string>();
foreach(var row in db.Query("SELECT ProviderUserId FROM webpages_OAuthMembership WHERE UserID = @0", currentUserId))
{
userIDs.Add( row.ProviderUserId);
}
//Now You have items in userIDs List