通过mysql查询将1列复制到另一列

Question

I have mysql database with following table...

| id | amount | tax |
+----+--------+-----+
|  1 | 500    |     |
+----+--------+-----+
|  2 | 100    |     |
+----+--------+-----+

I have to delete amount column but before doing that i want to shift all data of amount row from amount row to tax row. How can it be done using mysql query? Please help.

Answer 1

UPDATE mytable SET tax = amount

你可以删除它之后

ALTER TABLE mytable DROP COLUMN amount; 

Answer 2

UPDATE yTable SET tax = amount

Or to rename instead of copying (much faster):

ALTER yTable CHANGE amount tax YOURDATATYPE;

Delete tax before renaming.

Answer 3

update TABLE_NAME set tax=amount;

会做。

Answer 4

update your_table_name set tax=amount

you can delete the column data

UPDATE your_table_name SET amount = NULL WHERE amount is not null;

or you can delete column itself

ALTER TABLE your_table_name DROP COLUMN amount