Как проверить, если дата, которую я выбираю из date time picker, больше, чем дата из моей базы данных SQL

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 private void btn_search_Click(object sender, EventArgs e)
        {
            
            SqlConnection conn = new SqlConnection("Data Source=......;Initial Catalog=Innux;Persist");
conn.Open();
            SqlDataAdapter SDA = new SqlDataAdapter("select dbo.Alteracoes.Data, dbo.Funcionarios.numero as no, dbo.Funcionarios.nome, DATEPART(hour, Falta) AS faltas, DATEPART(hour, Coluna2) AS  horasextra  from dbo.Alteracoes inner join dbo.Funcionarios on dbo.Alteracoes.IDFuncionario = dbo.Funcionarios.IDFuncionario inner join dbo.Departamentos on dbo.Funcionarios.IDDepartamento = dbo.Departamentos.IDDepartamento WHERE Data = '" + dateTimePicker1.Value.ToString("yyyy/MM/dd") + "'", conn);

            DataSet dt = new DataSet();

            SDA.Fill(dt, "dbo.Alteracoes.Data");
            dataGridView1.DataSource = dt.Tables["dbo.Alteracoes.Data"];
            conn.Close();
        }

        private void dateTimePicker1_ValueChanged(object sender, EventArgs e)
        {
          

        }

This code search for the data  from the date i choose. 
And now i just want cheack if the date selected is < from (select u_recpica from e_industrial.dbo.e1) this table. If true show the data, if not is not valid  

Что я уже пробовал:

<pre>
 private void btn_search_Click(object sender, EventArgs e)
        {
            
            SqlConnection conn = new SqlConnection("Data Source=......;Initial Catalog=Innux;Persist");
conn.Open();
            SqlDataAdapter SDA = new SqlDataAdapter("select dbo.Alteracoes.Data, dbo.Funcionarios.numero as no, dbo.Funcionarios.nome, DATEPART(hour, Falta) AS faltas, DATEPART(hour, Coluna2) AS  horasextra  from dbo.Alteracoes inner join dbo.Funcionarios on dbo.Alteracoes.IDFuncionario = dbo.Funcionarios.IDFuncionario inner join dbo.Departamentos on dbo.Funcionarios.IDDepartamento = dbo.Departamentos.IDDepartamento WHERE Data = '" + dateTimePicker1.Value.ToString("yyyy/MM/dd") + "'", conn);

            DataSet dt = new DataSet();

            SDA.Fill(dt, "dbo.Alteracoes.Data");
            dataGridView1.DataSource = dt.Tables["dbo.Alteracoes.Data"];
            conn.Close();
        }

        private void dateTimePicker1_ValueChanged(object sender, EventArgs e)
        {
          

        }

This code search for the data  from the date i choose. 
And now i just want cheack if the date selected is < from (select u_recpica from e_industrial.dbo.e1) this table. If true show the data, if not is not valid 

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