在SQL中，如何在现有表中添加新列后添加值？

Question

I created a table and inserted 3 rows. Then I added a new column using alter . How can I add values to the column without using any null values?

Answer 1

Two solutions.

1. Provide a default value for the column. This value will be used initially for all existing rows. The exact syntax depends on your database, but will will usually look like ..

this:

ALTER TABLE YourTable
ADD YourNewColumn INT NOT NULL
DEFAULT 10 
WITH VALUES;

2. Add the column with null values first. Then update all rows to enter the values you want.

Like so:

ALTER TABLE YourTable
ADD YourNewColumn INT NULL;

UPDATE YourTable SET YourNewColumn = 10; -- Or some more complex expression

Then, if you need to, alter the column to make it not null :

ALTER TABLE YourTable ALTER COLUMN YourNewColumn NOT NULL;

Answer 2

我认为下面的SQL对你有用

update table_name set newly_added_column_name = value;

Answer 3

Why don't you use UPDATE statement:

UPDATE tablename SET column=value <WHERE ...>

WHERE is optional. For instance in T-SQL for table:

I can update column NewTestColumn by this statement:

UPDATE [dbo].[Table] SET [NewTestColumn] = 'Some value'

Answer 4

Suppose you have a Employee table with these columns Employee_ID, Emp_Name,Emp_Email initially. Later you decide to add Emp_Department column to this table. To enter values to this column, you can use the following query :

Update *Table_Name* set *NewlyAddedColumnName*=Value where *Columname(primary key column)*=value

Example update TblEmployee set Emp_Department='Marketing' where Emp_ID='101'

Answer 5

   update table_name
   set new_column=value

Answer 6

假设emp是表，Comm是新列，则触发下面的查询。

update emp set Comm=5000 

Answer 7

Update table table_name set column_name = value where 'condition'; 

我更喜欢使用p.key列来获得最佳结果。

Answer 8

For Microsoft SQL :

UPDATE TABLE_NAME SET COLUMN_NAME=10;

here 10 means it will set all values by default to 10