Sleep Command in T-SQL?

Question

Is there to way write a T-SQL command to just make it sleep for a period of time? I am writing a web service asynchronously and I want to be able to run some tests to see i

Answer 1

Here is a very simple piece of C# code to test the CommandTimeout with. It creates a new command which will wait for 2 seconds. Set the CommandTimeout to 1 second and you will see an exception when running it. Setting the CommandTimeout to either 0 or something higher than 2 will run fine. By the way, the default CommandTimeout is 30 seconds.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

using System.Data.SqlClient;

namespace ConsoleApplication1
{
  class Program
  {
    static void Main(string[] args)
    {
      var builder = new SqlConnectionStringBuilder();
      builder.DataSource = "localhost";
      builder.IntegratedSecurity = true;
      builder.InitialCatalog = "master";

      var connectionString = builder.ConnectionString;

      using (var connection = new SqlConnection(connectionString))
      {
        connection.Open();

        using (var command = connection.CreateCommand())
        {
          command.CommandText = "WAITFOR DELAY '00:00:02'";
          command.CommandTimeout = 1;

          command.ExecuteNonQuery();
        }
      }
    }
  }
}

Answer 2

WAITFOR DELAY 'HH:MM:SS'

I believe the maximum time this can wait for is 23 hours, 59 minutes and 59 seconds.

Here's a Scalar-valued function to show it's use; the below function will take an integer parameter of seconds, which it then translates into HH:MM:SS and executes it using the EXEC sp_executesql @sqlcode command to query. Below function is for demonstration only, i know it's not fit for purpose really as a scalar-valued function! :-)

    CREATE FUNCTION [dbo].[ufn_DelayFor_MaxTimeIs24Hours]
    (
    @sec int
    )
    RETURNS
    nvarchar(4)
    AS
    BEGIN


    declare @hours int = @sec / 60 / 60
    declare @mins int = (@sec / 60) - (@hours * 60)
    declare @secs int = (@sec - ((@hours * 60) * 60)) - (@mins * 60)


    IF @hours > 23 
    BEGIN
    select @hours = 23
    select @mins = 59
    select @secs = 59
    -- 'maximum wait time is 23 hours, 59 minutes and 59 seconds.'
    END


    declare @sql nvarchar(24) = 'WAITFOR DELAY '+char(39)+cast(@hours as nvarchar(2))+':'+CAST(@mins as nvarchar(2))+':'+CAST(@secs as nvarchar(2))+char(39)


    exec sp_executesql @sql

    return ''
    END

IF you wish to delay longer than 24 hours, I suggest you use a @Days parameter to go for a number of days and wrap the function executable inside a loop... e.g..

    Declare @Days int = 5
    Declare @CurrentDay int = 1

    WHILE @CurrentDay <= @Days
    BEGIN

    --24 hours, function will run for 23 hours, 59 minutes, 59 seconds per run.
    [ufn_DelayFor_MaxTimeIs24Hours] 86400

    SELECT @CurrentDay = @CurrentDay + 1
    END

Answer 3

You can also "WAITFOR" a "TIME":

    RAISERROR('Im about to wait for a certain time...', 0, 1) WITH NOWAIT
    WAITFOR TIME '16:43:30.000'
    RAISERROR('I waited!', 0, 1) WITH NOWAIT

Answer 4

Look at the WAITFOR command.

E.g.

-- wait for 1 minute
WAITFOR DELAY '00:01'

-- wait for 1 second
WAITFOR DELAY '00:00:01'

This command allows you a high degree of precision but is only accurate within 10ms - 16ms on a typical machine as it relies on GetTickCount. So, for example, the call WAITFOR DELAY '00:00:00:001' is likely to result in no wait at all.