executereader

Will this cancel an ExecuteReaderAsync

由 筅森魡賤 提交于 2020-01-07 08:15:08
问题 If I make a CancellationTokenSource and pass it down to a place where I perform a query like this: await command.Connection.OpenAsync(); dataReader = await command.ExecuteReaderAsync(_cancellationToken); If immediately below this I add the following: _cancellationToken.ThrowIfCancellationRequested(); resultTable.Load(dataReader); If on a different thread _cancellationTokenSource.Cancel() is called, will the query be cancelled appropriately? 回答1: Was able to find a decent solution to the

How to read specific column and cell in mysql in c#?

由 邮差的信 提交于 2019-12-24 12:59:21
问题 I use ExecuteReader to select all (SELECT*) for all field like this string query = "SELECT* FROM tb_patient_information "; if (this.OpenConnection() == true) { //Create Command MySqlCommand cmd = new MySqlCommand(query, connection); //Create a data reader and Execute the command MySqlDataReader dataReader = cmd.ExecuteReader(); while (dataReader.Read()) { ... } but I only want to select in specific column and cell like in red square.. like this picture 回答1: You can get the specific column

LinqToSQL and the exception “ ExecuteReader requires an open and available Connection.”

由 梦想的初衷 提交于 2019-12-24 08:01:26
问题 I have a collection called dbUsers of type IQueryable These are pulled from a linqtosql database context i.e. IQueryable<Data.LinqToSQL.User> dbUsers = DBContext.Users Calling ToList on this object: IList<Data.LinqToSQL.User> users = dbUsers.ToList(); Results in an exception: ExecuteReader requires an open and available Connection. The connection's current state is connecting. What am I doing wrong here? Cheers 回答1: see if this works for you: IList<Data.LinqToSQL.User> users = (from u in

Why is this SqlCeCommand ExecuteReader call failing?

由 生来就可爱ヽ(ⅴ＜●) 提交于 2019-12-23 06:40:45
问题 I adapted my code below from "Microsoft .NET Compact Framework" by Wigley and Wheelwright: SqlCeConnection cn = new SqlCeConnection(@"Data Source=\My Documents\Traffic.sdf"); String sSQL= "SELECT CarID, Reg, Location FROM Cars"); SqlCeCommand cmdSelect = new SqlCeCommand(sSQL, cn); cmdSelect.CommandType = CommandType.Text; SqlCeDataReader dtr = cmdSelect.ExecuteReader(CommandBehavior.Default); // It's "cmd." instead of "cmdSelect." in the book, but that doesn't compile while (dtr.Read()) {

C# Invalid attempt to call Read when reader is closed

由 元气小坏坏 提交于 2019-12-18 11:47:50
问题 I am having Invalid attempt to call Read when reader is closed error when I am doing 3 tier project in C# language. What I am trying to do is retrieve address data column by joining two tables together and display in a drop down list. Here is my data access layer: public List<Distribution> getDistributionAll() { List<Distribution> distributionAll = new List<Distribution>(); string address; SqlDataReader dr = FoodBankDB.executeReader("SELECT b.addressLineOne FROM dbo.Beneficiaries b INNER JOIN

Would executing the SqlCommand be completely moot/redundant, and slow things down?

由 被刻印的时光 ゝ 提交于 2019-12-11 13:18:21
问题 Thanks to some tips and reminders here, I changed my code from this kludgy mess: try { DataSet dsUsage = new DataSet(); SqlConnection conn = new SqlConnection("SERVER=PROSQL05;DATABASE=platypusdata;UID=duckbill;PWD=poisonToe42;Connection Timeout=0"); SqlDataAdapter da = new SqlDataAdapter(); SqlCommand cmd = conn.CreateCommand(); cmd.CommandText = String.Format("Exec sp_ViewProductUsage_MappingRS '{0}', '{1}', '{2}'", mammal, dateBegin, dateEnd); da.SelectCommand = cmd; conn.Open(); da.Fill

ExecuteReader CommandText property has not been properly initialized

由 孤者浪人 提交于 2019-12-04 04:56:08
问题 First of all sorry if some of the code isn't right. I'm still new to using sql on vb.net I have the following code: Imports MySql.Data.MySqlClient Imports System.Data.SqlClient Public Class Form1 Private Sub btnLoad_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnLoad.Click Dim objConn As MySqlConnection Dim objDataset As New DataSet Dim objDataAdapter As MySqlDataAdapter Dim myCommand As MySqlCommand Dim sqlConn As String objConn = New MySqlConnection("server

SqlDataReader hangs on GetValue() method and SNIReadSyncOverAsync

由 寵の児 提交于 2019-12-02 11:34:16
问题 We have an extremely weird problem at hand. The .Net SqlDataReader object gets stuck while reading a value on GetValue() method. There are no exceptions and it does not timeout for at least more than 10 minutes which is really long time. After more than 10 minutes, it throws this error: General Exception - !ET:SqlException{CRLF}!M:Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding.{CRLF}General Exception - !ET:Win32Exception{CRLF}

SqlDataReader hangs on GetValue() method and SNIReadSyncOverAsync

由 我是研究僧i 提交于 2019-12-02 06:23:08
We have an extremely weird problem at hand. The .Net SqlDataReader object gets stuck while reading a value on GetValue() method. There are no exceptions and it does not timeout for at least more than 10 minutes which is really long time. After more than 10 minutes, it throws this error: General Exception - !ET:SqlException{CRLF}!M:Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding.{CRLF}General Exception - !ET:Win32Exception{CRLF}!M:The wait operation timed out{CRLF}! Stack trace obtained through process dump. 000000001b2ee6f8

ExecuteReader CommandText property has not been properly initialized

由 对着背影说爱祢 提交于 2019-12-02 01:54:26
First of all sorry if some of the code isn't right. I'm still new to using sql on vb.net I have the following code: Imports MySql.Data.MySqlClient Imports System.Data.SqlClient Public Class Form1 Private Sub btnLoad_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnLoad.Click Dim objConn As MySqlConnection Dim objDataset As New DataSet Dim objDataAdapter As MySqlDataAdapter Dim myCommand As MySqlCommand Dim sqlConn As String objConn = New MySqlConnection("server=localhost;userid=root;database=attendance_system") myCommand = objConn.CreateCommand objConn.Open() Dim
订阅 executereader