store null values in database

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i have a form in which there are some fields name,last name,birthday etc.some fields are optional i-e last name,birthday etc.i want to store null value in database if user don't fill these optional fields.how can i do this?in c# windows app

Posted 15-Sep-14 5:33am

Nainaaa

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OriginalGriff · Answer 1 · 2014-09-15T05:45:00

Solution 1

Just use a parameterised query (as you should with all user input to prevent SQL Injection problems) and pass DBNull.Value:

C#

using (SqlCommand cmd = new SqlCommand("INSERT INTO MyTable (MyColumn) VALUES (@VAL)", con))
    {
    object val = tbUserInput.Text;
    if (string.IsNullOrWhiteSpace(tbUserInput.Text)) val = DBNull.Value;
    cmd.Parameters.AddWithValue("@VAL", val);
    ...
    }

Posted 15-Sep-14 5:45am

OriginalGriff

Updated 15-Sep-14 5:46am

v2

Comments

Nainaaa 15-Sep-14 14:12pm

this is for the string.i want for the int type textboxes and combo boxes.

OriginalGriff 15-Sep-14 14:30pm

It's
an
example
...

I'm not about to provide you with an example that covers every control and database type combination on the planet, now am I?

Afzaal Ahmad Zeeshan · Answer 2 · 2014-09-15T09:47:00

Do as OriginalGriff has said, but one more thing. Do not forget to allow the Null values in the column which setting the Database table schema. So that if you're passing a Null value, it might/should not raise an error saying, it was expecting a value not a null.

By default non-primary, non-identity etc columns allow the null value and primary identity and key columsn don't allow null. They always require some value to work on.

So, when you're using the above code, you must allow null to be added in the column.