我想从C＃中的DateTimePicker对象更新我的数据库表中的“Datetime”数据类型的字段

Question

Note: Don't care with Connection becuse the connection work. Field in database is DateTime

DateTime dtc = Convert.ToDateTime(dateTimePicker1.Value.Date);

cmd = new SqlCommand("UPDATE LAB_TESTING set Lab_Nam='" + lab_id + "',Rslt_lb='" + 
                     textBox1.Text + "',Tst_Dat='" + dtc + "' Where Lab_ID='" + 
                     bindex + "'", con);
con.Open();
cmd.ExecuteNonQuery();
MessageBox.Show("You Update recored successfully", "delete", MessageBoxButtons.OK, MessageBoxIcon.Information);
dataGridView1.DataSource = null;
con.Close();
readdatagrid1();

after Run program , I got Conversion failed when converting date and/or time from character string.

Answer 1

Don't use string concatenation to build your queries ( SQL injection alert , also read this !). Use parameterized queries . As for your problem: format the date as yyyy-MM-dd ( ISO 8601 ) and it'll work.

If you'd have used parameterized queries correctly you could've just passed in the DateTime as-is and the driver would've ensured the value would get passed correctly to SQL regardless the "format" / locale setting / whatever since the value would be passed as a DateTime instead of a string. Something like this:

cmd = new SqlCommand(@"UPDATE LAB_TESTING set Lab_Nam = @labnam,
                            Rslt_lb = @result, Tst_Dat = @tstdat
                            Where Lab_ID = @id", con);

cmd.Parameters.AddWithValue("@labnam", lab_id );
cmd.Parameters.AddWithValue("@result", textBox1.Text);
cmd.Parameters.AddWithValue("@tstdat", dateTimePicker1.Value.Date);
cmd.Parameters.AddWithValue("@id", bindex);

con.Open();
cmd.ExecuteNonQuery();

Other than that I also recommend to wrap the con and cmd in a using() { ... } statement so that you can be sure this stuff gets disposed properly and that you give your variables and fieldnames decent names and use a consistent naming scheme.

Now repeat after me:

• I will never, ever, run queries again that have been string-concatenated together anymore!

• From now on I will use parameterized queries

• If I need to run string-concatenated queries ever again I will make sure all values are escaped properly

Repeat the above aloud, at least 50 times.

Answer 2

Try this

DateTime dtc = Convert.ToDateTime(dateTimePicker1.Value.ToString("dd/MM/yyyy"));

or else

you can also do this

DateTime dtc = Convert.ToDateTime(dateTimePicker1.Text)

If you are getting this error with your SQL code than have a look here

Answer 3

这对你有用。

    var date = (DateTime)dateTimePicker1.SelectedDate.Value;