[英]Wait for creation database to finish
我有這樣的代碼:
using (var sqlConnection = new SqlConnection(connectionString))
{
sqlConnection.Open();
using (var sqlCommand = new SqlCommand(scriptText, sqlConnection))
{
sqlCommand.ExecuteNonQuery();
}
}
我第一次調用它來創建一個數據庫,然后我形成一個連接字符串到這個數據庫,並嘗試做一些工作( Open
工作正常,並表示連接實際上是為第二個連接打開)。 但我得到一個“現有連接被遠程主機強行關閉”,我可以看到sql日志“無法找到數據庫ID 9.數據庫可能尚未激活或可能正在轉換”。 所以,實際上ExecuteNonQuery
在作業完成之前返回。 當然,我可以直接垃圾郵件直到情況發生變化,但有沒有更好的方法等待數據庫准備工作?
這個完整的樣本適合我。
它創建數據庫,創建表,在表中放置一行。
不知道你的結果有什么問題。
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.SqlClient;
namespace GranadaCoder.PlaygroundConsole.SqlStuff
{
public class SqlPlayground
{
public static void EntryPointStuff()
{
string databaseName = "MyFirstDatabaseABC";
string connectionString = string.Empty;
string commandText = string.Empty;
int returnValue = 0;
string msg = string.Empty;
SqlConnectionStringBuilder builder = new SqlConnectionStringBuilder();
builder["Initial Catalog"] = "master";
builder["integrated Security"] = true;
builder["Server"] = @"MyMachine\MyInstance";
connectionString = builder.ConnectionString;
commandText = string.Format("IF EXISTS (Select * from sys.databases where name = N'{0}') DROP DATABASE [{0}]", databaseName);
returnValue = RunACommand(connectionString, commandText);
msg = string.Format("'{0}', {1}", returnValue, commandText);
Console.WriteLine(msg);
commandText = string.Format("IF NOT EXISTS (Select * from sys.databases where name = N'{0}') CREATE DATABASE [{0}]", databaseName);
returnValue = RunACommand(connectionString, commandText);
msg = string.Format("'{0}', {1}", returnValue, commandText);
Console.WriteLine(msg);
/* Change the Catalog */
builder["Initial Catalog"] = databaseName;
connectionString = builder.ConnectionString;
commandText = "if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[CodeCategory]') and OBJECTPROPERTY(id, N'IsUserTable') = 1) BEGIN DROP TABLE [dbo].[CodeCategory] END ";
returnValue = RunACommand(connectionString, commandText);
msg = string.Format("'{0}', {1}", returnValue, commandText);
Console.WriteLine(msg);
commandText = "CREATE TABLE [dbo].[CodeCategory] ( CodeCategoryKey [smallint] not null , CodeCategoryName varchar(64) not null ) ";
returnValue = RunACommand(connectionString, commandText);
msg = string.Format("'{0}', {1}", returnValue, commandText);
Console.WriteLine(msg);
commandText = "INSERT INTO [dbo].[CodeCategory] ( CodeCategoryKey , CodeCategoryName ) Select 1001 , 'MyFirstCodeCategory' ";
returnValue = RunACommand(connectionString, commandText);
msg = string.Format("'{0}', {1}", returnValue, commandText);
Console.WriteLine(msg);
commandText = "Select Count(*) from [dbo].[CodeCategory]";
returnValue = RunACommand(connectionString, commandText);
msg = string.Format("'{0}', {1}", returnValue, commandText);
Console.WriteLine(msg);
}
private static int RunACommand(string connectionString, string scriptText)
{
int returnValue = 0;
using (var sqlConnection = new SqlConnection(connectionString))
{
sqlConnection.Open();
using (var sqlCommand = new SqlCommand(scriptText, sqlConnection))
{
returnValue = sqlCommand.ExecuteNonQuery();
}
sqlConnection.Close();
}
return returnValue;
}
}
}
這對我有用(沒有例外):
static void Main(string[] args)
{
try
{
SqlPlayground.EntryPointStuff();
Console.WriteLine("Press Enter after deleting the database in SSMS manually with 'Close Existing Connections' checked.");
Console.ReadLine();
SqlPlayground.EntryPointStuff();
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
Console.WriteLine("Pressing Enter To End");
Console.ReadLine();
}
在我的情況下添加Thread.Sleep(...)幫助,但根本原因是失敗的連接被緩存並由方法SqlConnection.Open()使用。 針對這種情況,請參閱此問題的答案 。 使用SqlConnection.ClearAllPools()清除池有幫助。
為什么等待幾秒鍾也有幫助呢? 似乎通過計時器自動清除池就足夠了。
如果您在創建后立即執行其他操作(例如更新數據庫架構),則可能會注意到此問題。 等待幾秒似乎解決了這個問題。
//wait for database creation
Thread.Sleep(3000);
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