Dapper参数化查询字符串值导致问题？

Question

我在下面使用dapper参数化了此Method＃1查询，问题是即使等待30秒后，使用此方法的查询也会超时，通常在使用纯SQL的SSMS上最多需要1秒。

但是，方法2的查询实际上可以在服务器端而不是参数化的查询中构建。我注意到的一件事是，它可能与FirstName和LastName的过滤器有关，我在方法2上为那些过滤器使用了单引号，但没有方法1的引用。

方法1有什么问题？

Method # 1

string query = "SELECT *
                FROM dbo.Customer c                
                WHERE c.MainCustomerId = @CustomerId 
                AND (@IgnoreCustomerId = 1 OR c.CustomerID = @FilterCustomerId)
                AND (@IgnoreFirstName = 1 OR c.FirstName = @FilterFirstName)
                AND (@IgnoreLastName = 1 OR c.LastName = @FilterLastName)
                AND (@IgnoreMemberStatus = 1 OR c.CustomerStatusID = @FilterMemberStatus)
                AND (@IgnoreMemberType = 1 OR c.CustomerTypeID = @FilterMemberType)
                AND (@IgnoreRank = 1 OR c.RankID = @FilterRank)
                ORDER BY c.CustomerId
                OFFSET @OffSet ROWS
                FETCH NEXT 50 ROWS ONLY";       



                _procExecutor.ExecuteSqlAsync<Report>(query, new
            {
                CustomerId = customerId,
                IgnoreCustomerId = ignoreCustomerId,
                FilterCustomerId = filter.CustomerID,
                IgnoreFirstName = ignoreFirstName,
                FilterFirstName = filter.FirstName,
                IgnoreLastName = ignoreLastName,
                FilterLastName = filter.LastName,
                IgnoreMemberStatus = ignoreMemberStatus,
                FilterMemberStatus = Convert.ToInt32(filter.MemberStatus),
                IgnoreMemberType = ignoreMemberType,
                FilterMemberType = Convert.ToInt32(filter.MemberType),
                IgnoreRank = ignoreRank,
                FilterRank = Convert.ToInt32(filter.Rank),
                OffSet = (page - 1) * 50
            });


    Method # 2      

            string queryThatWorks =
                            "SELECT *
                 FROM dbo.Customer c                
                WHERE c.MainCustomerId = @CustomerId 
                AND ({1} = 1 OR c.CustomerID = {2})
                AND ({3} = 1 OR c.FirstName = '{4}')
                AND ({5}= 1 OR c.LastName = '{6}')
                AND ({7} = 1 OR c.CustomerStatusID = {8})
                AND ({9} = 1 OR c.CustomerTypeID = {10})
                AND ({11} = 1 OR c.RankID = {12})
                ORDER BY c.CustomerId
                OFFSET {13} ROWS
                FETCH NEXT 50 ROWS ONLY";

                _procExecutor.ExecuteSqlAsync<Report>(string.Format(queryThatWorks,
                customerId,
                ignoreCustomerId,
                filter.CustomerID,
                ignoreFirstName,
                filter.FirstName,
                ignoreLastName,
                filter.LastName,
                ignoreMemberStatus,
                 Convert.ToInt32(filter.MemberStatus),
                 ignoreMemberType,
                 Convert.ToInt32(filter.MemberType),
                 ignoreRank,
                  Convert.ToInt32(filter.Rank),
                 (page - 1) * 50
                ), null);

Answer 1

我以前看过无数次了。

我敢打赌，您的列是varChar，但Dapper将您的参数发送为nVarChar。发生这种情况时，SQL Server必须对存储在每一行中的值进行转换。除了速度很慢之外，这还会阻止您使用索引。

请参阅https://github.com/StackExchange/dapper-dot-net中的 “ Ansi字符串和varchar”