Question

So this is the code I have tried, in C#, which failed to give me the result I needed.

SqlCommand comm = new SqlCommand("exec sys.xp_readerrorlog 0,1,'','',@StartDate,@EndDate,N'Desc'");, conn);
comm.Parameters.AddWithValue("@StartDate", "");
comm.Parameters.AddWithValue("@EndDate", "");

SqlDataReader dr = comm.ExecuteReader();

while (dr.Read())
{
    Console.WriteLine(dr.GetString(0));
}

Basically, I need to extract data from these logs (which gets pulled from the SQL Server through this stored procedure), and it seems that When I use a dataReader, there are no records, and if I use a dataset with data adapter, there are also no tables/records in the dataset. This information is critical for me to query.

Is there a way that I can still query the SQL Server error logs without having to resort to stored procedures?

ANOTHER UPDATE:

The parameters for this extended stored procedures are:

• Value of error log file you want to read: 0 = current, 1 = Archive, 2 = etc…

• Log file type: 1 or NULL = error log, 2 = SQL Agent log

• Search string 1: String one you want to search for

• Search string 2: String two you want to search for to further refine
  the results

• Search from start time

• Search to end time

• Sort order for results: N’asc’ = ascending, N’desc’ = descending

Another method I tried

SqlCommand comm = new SqlCommand(@"exec sys.xp_readerrorlog 0,1,'','',null,null,N'Desc'", conn);
SqlDataAdapter da = new SqlDataAdapter(comm);
DataSet ds = new DataSet();
Console.WriteLine(ds.Tables.Count); //0 returned: no data in dataset

If i was allowed to use stored procedures to query the data, I could have used this following extract, but it would have been deployed too much and be a pain to maintain and decommission

    IF (EXISTS( SELECT * FROM sys.procedures where name = 'writelogs' ))
BEGIN
    DROP PROCEDURE Writelogs;
END
GO

CREATE PROCEDURE WriteLogs @Servername varchar(40),@InstanceName varchar(40),@Pattern varchar(max),@ParamBeginDate varchar(40), @ParamEndDate varchar(40) AS
BEGIN 

    DECLARE @BeginDate DateTime
    DECLARE @EndDate DateTime
    DECLARE @NextQueryID int
    
    --First we have to convert the timestamps EndDate and BeginDate to something usable
    IF (@ParamBeginDate = 'Beginning')
    BEGIN
        SET @BeginDate = null;  --null will cause sys.xp_readerrorlog to read from beginning
    END
    ELSE IF (@ParamBeginDate = 'Last')
    BEGIN
        SELECT TOP 1 @BeginDate = L.TimeLogged FROM LogTable L ORDER BY L.TimeLogged Desc
    END
    ELSE
    BEGIN
        BEGIN TRY   
            SET @BeginDate = CAST(@ParamBeginDate AS DATETIME);
        END TRY
        BEGIN CATCH
            SET @BeginDate = null;
        END CATCH
    END
    IF (@ParamEndDate = 'Now')
    BEGIN
        SET @EndDate = GETDATE();  --null will cause sys.xp_readerrorlog to read till now
    END
    ELSE
    BEGIN
        BEGIN TRY   
            SET @EndDate = CAST(@ParamEndDate AS DATETIME);
        END TRY
        BEGIN CATCH
            SET @EndDate = GETDATE();
        END CATCH
    END
    
    --Temporary Table to store the logs in the format it is originally written in
    CREATE TABLE TMP
                (LogDate DateTime2
                ,Processinfo varchar(40)
                ,[Text] varchar(max))

    --truncate the milliseconds (else ALL records will be retrieved)
    SET @EndDate= dateadd(millisecond, -datepart(millisecond, @EndDate),@EndDate);
    SET @BeginDate= dateadd(millisecond, -datepart(millisecond, @BeginDate),@BeginDate);
    
    INSERT INTO TMP exec sys.xp_readerrorlog 0,1,'','',@BeginDate,@EndDate,N'DESC';
    SELECT TOP 1 L.TimeLogged FROM LogTable L ORDER BY L.Timelogged desc
    INSERT INTO LogTable
    SELECT @Servername,@InstanceName,T.[text],T.LogDate,GETDATE(),0,0,null,@NextQueryID FROM TMP t WHERE PATINDEX(@Pattern,t.[Text]) > 0;
    DROP TABLE TMP;
END

Answer 1

You can’t use AddWithValue for the dates.

If the dates are blank, then you need to pass null as the value, not an empty string. Those have completely different meanings.

To test, open Management Studio and execute the following:

exec sys.xp_readerrorlog 0,1, '', '', '', ''

That will have zero results. However if you do this:

exec sys.xp_readerrorlog 0,1, '', '', null, null

You will get back a lot of records.

---

BTW, your update is still wrong. The dataset code you have will never do anything. Change it to:

SqlCommand comm = new SqlCommand(@"exec sys.xp_readerrorlog 0,1,'','',null,null,N'Desc'", conn);
SqlDataAdapter da = new SqlDataAdapter(comm);
DataSet ds = new DataSet();
da.Fill(ds, "sometablename");
Console.WriteLine(ds.Tables.Count); //0 returned: no data in dataset

Note the fill command…