将特定列从一个表复制到另一个

Question

I have two tables InventoryOriginal and InventoryBackup. Both had 20 columns, but now InventoryOriginal has changed and has only 12 columns which are common with InventoryBackup. And I need to copy each month's data from InventoryOriginal to InventoryBackup, but it will give me an error because the column number do not match.

I use the simple statement to copy the data which is

INSERT INTO InventoryBackup
Select * from  InventoryOriginal where Period  = '2020-01-01'

but now the number of columns has changed InventoryOriginal has 12 and InventoryBackup has 20. Can I copy the 12 columns from InventoryOriginal to InventoryBackup and the rest columns can be blank?

getting error - Column name or number of supplied values does not match table definition.

Answer 1

The general way you do this is to mention the target and source columns you want to use. For example, for 3 columns you would use:

INSERT INTO InventoryBackup (col1, col2, col3)
SELECT col1, col2, col3
FROM InventoryOriginal
WHERE Period = '2020-01-01';

Keep in mind that any columns in the target backup table for which were not mentioned would either be assigned a NULL value, or possibly a default value, if the table definition support that.

Answer 2

The simple answer is yes, but you'll likely need to adjust your SQL statement to specify the columns. Eg.

INSERT INTO InventoryBackup (col1, col2, col3, ...)
SELECT col1, col2, col3, ... FROM InventoryOriginal

This will be fine, as long as the extra columns in the "backup" table (that are no longer in the "orignal" table) allow NULLs. If they don't, then you'll need to specify a blank value (or 0, if they're numeric) when you insert. Eg.

INSERT INTO InventoryBackup (col1, col2, col3, extra1, extra2, ...)
SELECT col1, col2, col3, '', 0, ... FROM InventoryOriginal

Hopefully that makes sense. The exact SQL statement that you're going to need is really going to depend on the actual structure of the "backup" table