如何使“日期"字段将Null插入数据库? [英] how can i make Date field insert Null into the database?

问题描述

嗨.

我已在VS2010中为BirthDate的文本框之一中编写了一条插入语句，我已在SQlserver 2008r2中为其指定了日期类型，
我在该字段的代码(参数输入)在下面:

Hi.

i have written an insert statement In VS2010 , in one of textbox which is for BirthDate , i have assigned Date type for it in SQlserver 2008r2,
and my code(parameter input) for that field is in below:

cmd.Parameters.Add("@BirthDate_M", SqlDbType.Date).Value = Convert.ToDateTime(BirthDateTextBoxMilad.Text);

每当我在文本框内不写任何日期时，就会出现此异常:
字符串未被识别为有效的DateTime.

虽然我希望每当我不在textbox中写任何东西时，都将Null插入数据库，所以我写了这段代码:

whenever i don''t write any date inside textbox this exception appears:
String was not recognized as a valid DateTime.

while i want that whenever i don''t write anything in textbox , Null to be inserted into the Database, so i wrote this code:

cmd.Parameters.Add("@BirthDate_M", SqlDbType.Date).Value = null;

但是如果我这样做，将会出现另一个异常:
参数化查询``(@FirstName nvarchar(5)，@ LastName nvarchar(5)，@ FatherName nvarch''需要未提供的参数``@BirthDate_M''.

but if i do this , another exception will appear:
The parameterized query ''(@FirstName nvarchar(5),@LastName nvarchar(5),@FatherName nvarch'' expects the parameter ''@BirthDate_M'', which was not supplied.

which indicate that i have to insert a date.how can i prevent this happens and make it insert Null into the database.

推荐答案

hi，

试试这个，

try this,

cmd.Parameters.Add("@BirthDate_M", SqlDbType.Date).Value = (BirthDateTextBoxMilad.Text.Trim()==string.empty) ? DbNull.value : Convert.ToDateTime(BirthDateTextBoxMilad.Text.Trim());

希望它能起作用

hope it works

试试这个:

Hi,
Try this:

DateTime? value = Convert.ToDateTime(BirthDateTextBoxMilad.Text);
if (value.HasValue)
{
    cmd.Parameters.Add("@BirthDate_M", SqlDbType.Date).Value = value;
}

--Amit

--Amit

尝试一下

try this

cmd.Parameters.Add("@BirthDate_M", SqlDbType.Date).Value = DBNull.Value;

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