如何在SQL Server 2008 r2中添加列值？

Question

I created a table called Dummy with 4 columns: Date, Year, Student_Names, Subject .

After a few days I need to add one more column name called Marks .

I know how to add column Marks by using the SQL query, I am using the query below:

Alter Table Dummy 
add Mark varchar(30)

After I add the column, all values are NULL, I need some value in the place of NULL.

How do I add those values? Values are mentioned in an Excel file.

Answer 1

Try,

Alter Table Dummy ADD Mark varchar(30) DEFAULT ''

or

UPDATE Dummy
SET [MArk] = 'new value'

Answer 2

your code is update Dummy set Marks = 10 where Student_Names = name you want to add marks to

like this you can add marks to all the students

good luck

Answer 3

You can update NULL values:

UPDATE Dummy
  SET Mark = "none"
WHERE Mark is NULL

Will set all the marks to "none".

Also, when adding the column, you can specify a default value:

ADD Mark varchar(30) NOT NULL DEFAULT 'none'

Answer 4

要更新Excel工作表中的值，您需要在Excel文件中编写Query（使用CONCATENATE函数）并在表上运行它。