Concat 字符串与带有 DateTime 字符串的查询

Question

我无法手动将 CurrentSystemTime 添加到我的查询中。查询存储在字符串变量中。但是连接部分给出了错误：

查询是：

string myQuery= @"SELECT MAX(ASD.eventDateTime) AS second, R.resourceID,R.resourceLoginID,ASD.agentID
                  FROM AgentStateDetail AS ASD INNER JOIN 
                  Resource AS R ON ASD.agentID = R.ResourceID WHERE ASD.eventDateTime >='" + DateTime.Today.ToString("yyyy-MM-dd h:mm:ss") + "'AND ASD.eventDateTime <='2016-10-18 23:59:59' 
                  GROUP BY R.ResourceID,R.resourceLoginID,ASD.agentID"

The Problem part is:

WHERE ASD.eventDateTime >='" + DateTime.Today.ToString("yyyy-MM-dd h:mm:ss") + "'

Error is:

Represent Text as unicode character Newline in constant.

Answer 1

您忘记以 @ 开始字符串的第二部分，这就是编译器修正换行符无效的原因：

string myQuery= @"SELECT MAX(ASD.eventDateTime) AS second, R.resourceID,R.resourceLoginID,ASD.agentID
                  FROM AgentStateDetail AS ASD INNER JOIN 
                  Resource AS R ON ASD.agentID = R.ResourceID WHERE ASD.eventDateTime >='" + DateTime.Today.ToString("yyyy-MM-dd h:mm:ss") + @"'AND ASD.eventDateTime <='2016-10-18 23:59:59' 
                  GROUP BY R.ResourceID,R.resourceLoginID,ASD.agentID"

Answer 2

您可以使用如下参数化查询，

string sql = "SELECT MAX(ASD.eventDateTime) AS second, R.resourceID, R.resourceLoginID, ASD.agentID FROM AgentStateDetail AS ASD INNER JOIN Resource AS R ON ASD.agentID = R.ResourceID WHERE ASD.eventDateTime >= @dateTimeStart AND ASD.eventDateTime <= @dateTimeEnd GROUP BY R.ResourceID,R.resourceLoginID,ASD.agentID";

using (SqlConnection connection = new SqlConnection(/* connection info */))
using (SqlCommand command = new SqlCommand(sql, connection))
{
    var dateTimeStart = new SqlParameter("dateTimeStart", SqlDbType.DateTime);
    dateTimeStart.Value = new DateTime("yyyy-MM-dd h:mm:ss");

    var dateTimeEnd = new SqlParameter("dateTimeEnd", SqlDbType.DateTime);
    dateTimeEnd.Value = new DateTime("yyyy-MM-dd h:mm:ss");

    command.Parameters.Add(dateTimeStart);
    command.Parameters.Add(dateTimeEnd);
    var results = command.ExecuteReader();
}

Concat 字符串与带有 DateTime 字符串的查询

Concat string with a Query with DateTime String

.net

c#

string

model-view-controller

informix