在日期列中插入默认日期获取空值？ [英] insert default date in date column getting null value?

问题描述

如果date_no列通过在C＃程序中使用插入查询获取空值，请帮助我如何在date_no列中插入默认日期。

help me hows to insert default date in date_no column if date_no column getting null value through insert query using in C# program.??????

推荐答案

让我们看看例子：

Let see the example:

DECLARE @dates TABLE(aDate DATETIME NULL)

DECLARE @myDate DATETIME

SET @myDate='2013-01-01'
INSERT INTO @dates (aDate)
VALUES(@myDate)

SET @myDate=NULL

INSERT INTO @dates (aDate)
VALUES(@myDate)

在上面的例子中， @dates 表定义了 aDate 字段，可以存储 NULL 值。因此，当您尝试添加可为空的值时，表格接受它。



将表格的定义更改为：

In above example, @dates table has defined aDate field which can store NULL values. So, when you try to add nullable values, table "accept" it.

Change the definition of your table to:

DECLARE @dates TABLE(aDate DATETIME NOT NULL)

并尝试添加NULL值。

会发生什么？发生错误：

and try to add NULL value.
What would happen? Error occurs:

Msg 515, Level 16, State 2, Line 12<br />
Cannot insert the value NULL into column ''aDate'', table ''@dates''; column does not allow nulls. INSERT fails.

如果要在NULL的情况下添加默认日期，请创建如下存储过程：

If you want to add default date in case of NULL, create stored procedure like this:

CREATE PROCEDURE AddNewDefaultDate
    @myDate DATETIME NULL
BEGIN
    INSERT INTO YourTable (DateColumn, Column1, Column2, Column3,... ColumnN)
    VALUES(COALESCE(@myDate, '1900-01-01'), 'a', 1,... 3)
END

AS prasad sekhar表示将表中date_no列的DEFAULT约束设置为要保存的默认值。不要通过C＃代码中的insert查询将值插入此列。每当在表上执行插入操作时，它总是会在此列中插入默认值。

AS prasad sekhar said set DEFAULT constraint of your date_no column in table to the default value you want to save. do not insert the value to this column through insert query from your C# code. it will always insert the default value t this column whenever an insert operation is done on table.

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