Question

I’m currently trying to populate a datagrid using a member of a class that uses SQLCommand to execute a stored procedure and return the results.

My class member (and where I believe the issues lies) is:

public DataView DisplayHealthIndicator(DateTime startDate, DateTime endDate)
{
    string queryString =
        "DECLARE @RC int"
        + "DECLARE @date_from datetime = dateadd(day, 0, datediff(day, 0, getdate()))"
        + "DECLARE @date_to datetime = dateadd(day, 0, datediff(day, 0, getdate()))"

        + "EXECUTE @RC = [Testing].[marlin].[support_retrieve_workflow_history] "
            + "@date_from "
            + ",@date_to"
        + "GO";

    using (SqlConnection connection = new SqlConnection(GetConnectionString()))
    {
        using (var cmd = new SqlCommand(queryString, connection))
        {
            connection.Open();

            var reader = cmd.ExecuteReader();

            var dt = new DataTable();
            dt.Load(reader);

            return dt.DefaultView;
        }
    }

}

and I’m calling this member using:

var db = new DatabaseHandle();
        dataGridWorkflow.ItemsSource = db.DisplayHealthIndicator(DateTime.Now, DateTime.Now);

However! I’m currently receiving the error:

Incorrect syntax near @date_from

Must declare the scalar variable @RC

To a degree I understand the error – I believe that I can’t declare variables in my sqlQuery string… but then, how do I do this?

I’m fairly sure that it doesn’t have any bearing on this, but in case it does, this is the contents of the stored procedure:

create procedure marlin.support_retrieve_workflow_history
(
    @date_from datetime,
    @date_to datetime
)
as
select  dateadd(day, 0, datediff(day, 0, e.event_date)) as 'Date',
        c.setting_secondary 'Workflow Category' ,
        d.setting_main as 'Error Type' ,
        sum(e.event_count) as 'Total'
from    marlin.support_events e
        inner join marlin.support_config c
            on e.event_category = c.setting_code
            and c.config_code = 60
        inner join marlin.support_config d
            on e.event_type = d.setting_code
            and d.config_code = 70
where   e.event_date between @date_from and @date_to
group by 
        e.event_date,
        c.setting_secondary ,
        d.setting_main

Answer 1

cmd.Parameters["@ReturnValue"] contains the return value – you don’t need to add a parameter in dynamic SQL

Add your parameters to the cmd

cmd.Parameters.AddWithValue("ParamName", Value);

Also change the cmd.CommandType (might not be called that, check members of cmd) to StoredProcedure

e.g.

using (SqlConnection connection = new SqlConnection(GetConnectionString()))
{
    using (var cmd = new SqlCommand(queryString, connection))
    {
        connection.Open();

        cmd.CommandType = ??.StoredProcedure; // Can't remember what enum name is prob SqlCommandType or something
        cmd.Parameters.AddWithValue("date_from", DateTime.blah.blah);
        cmd.Parameters.AddWithValue("date_to", DateTime.blah.blah);
        var reader = cmd.ExecuteReader();

        var dt = new DataTable();
        dt.Load(reader);

        return dt.DefaultView;
    }
}

Disclaimer: Some of these prop names, the name of the return value param might not be correct so check the docs 🙂