Question

我有这个：

int id = 10;
long partnerId = 20;
long? groupId = null;
DateTime startDate = Datetime.Now.AddDays(-5);
DateTime endDate = Datetime.Now;
bool isTesting = true;
bool isActive = false;

query = @"SELECT Vita as VitalLevel,count(distinct ccrid) as Answers, Vitald as VitalType
                      FROM CORE.vRecipientsc rd
                      INNER JOIN Recipiendy rs ON rs.CRRID = rd.RID
                      INNER JOIN RecipientStungs rsvr ON rsvr.StudyId = rs.Id 
                      WHERE SBURID = {0} 
                      AND ({5} IS null OR {5}=SbuGroupRID)
                      AND rs.DTUTC_Created >= '{1}' 
                      AND rs.DTUTC_Created <= '{2}'
                      AND rsvr.VitalTypeId = 8 
                      AND rsvr.VitalValue <> '' 
                      AND (rd.isTesting = {3} or rd.isTesting = 0)
                      AND rd.IsActive= {4}
                      GROUP BY rsvr.VitalValue, rsvr.VitalLevel, rsvr.VitalTypeId";

String.Format(query, new object[] {
            partnerId, startDate, endDate, Convert.ToInt32(isTesting), Convert.ToInt32(isActive), groupId
        });

然后我与数据库建立连接并执行多个查询，但是当我执行查询时，string.format中的空值被替换为空格，我希望替换为groupId变量的行直接设置为null。我能用C＃做这个吗？

Answer 1

您可以将线条本身用作最后一个参数：

将AND ({5} IS null OR {5}=SbuGroupRID)替换为{5}，并将最后一个参数的值设置为groupId.HasValue ? string.Format("AND ({0} IS null OR {0}=SbuGroupRID)", groupId) : string.Empty

您可以在查询字符串之前将其移动到另一个变量中，并将该变量用作最后一个参数。

Answer 2

您可以将String.Format Method (String, Object[])和??用于可以为空的值。

String.Format(query, partnerId, startDate, endDate, Convert.ToInt32(isTesting), Convert.ToInt32(isActive), groupId ?? "null");

或者您可以使用相同的方法和三元运算符

String.Format(query, new object[] { partnerId, startDate, endDate, Convert.ToInt32(isTesting), Convert.ToInt32(isActive), groupId != null ? groupId.ToString() : "null" });

强制string.format为查询设置空值

2 个答案: