问题描述
我有以下代码.
using (SqlConnection connection = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString))
{
connection.Open();
SqlCommand select = new SqlCommand("SELECT RTRIM(LTRIM(PART_NO)) AS PART_NO, record FROM [RMAData].[dbo].[IMPORTING_ORDER_EDI] WHERE sessionID = '" + Session.SessionID + "'", connection);
SqlDataReader reader = select.ExecuteReader();
if (reader.HasRows)
{
while (reader.Read())
{
if (!currentPart.IsActive)
{
// this part is not active, set the active flag in sql to 0
SqlCommand update = new SqlCommand("UPDATE [RMAData].[dbo].[IMPORTING_ORDER_EDI] SET valid = 0, active = 0 WHERE record = " + reader["record"].ToString() + ";", connection);
update.ExecuteNonQuery();
}
else
{
///blah
}
}
reader.Close();
}
}
但这会导致以下异常...
but this causes the following exception...
System.InvalidOperationException: 已经有一个打开的 DataReader与必须先关闭的此命令相关联.
我需要读取返回的每一行,对数据进行一些验证并在必要时进行更新,然后继续下一条记录.如果在循环 reader.Read()
时不能使用 SqlCommand
,我该如何实现?
I need to read each row returned, do some validation on the data and make an update if necessary, then continue to the next record. How can I achieve this if I can't use a SqlCommand
while looping through reader.Read()
?
推荐答案
另一种方法是不添加 MultipleActiveResultSets=True - 这样做会有一点性能损失 - 所以像这样:
An alternative is not add MultipleActiveResultSets=True - there is a small performance penalty for doing so - and so something like this:
using (SqlConnection connection = new ...))
{
connection.Open();
SqlCommand select = new SqlCommand(...);
SqlDataReader reader = select.ExecuteReader();
var toInactivate = new List<string>();
if (reader.HasRows)
{
while (reader.Read())
{
if (!currentPart.IsActive)
{
toInactivate.Add(reader["record"].ToString());
}
else
{
///blah
}
}
reader.Close();
}
SqlCommand update = new SqlCommand("UPDATE ... SET valid = 0, active = 0 " +
"WHERE record IN(" + string.Join(",", toInactivate) + ");", connection);
update.ExecuteNonQuery();
}
它的优点是在单个 SQL 语句中更新所有必需的记录.
which has the advantage of updating all the required records in a single SQL statement.
当然,如果使用 EF 和 Linq,整个事情会变得更加整洁.
And of course the whole thing would be so much neater using EF and Linq.
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