How can I sum two columns in SQL?-CodePudding

I have a table with 2 columns:

CREATE TABLE Numbers(
    col1 float,
    col2 float
);
INSERT INTO Numbers(col1, col2)
VALUES('0.6', '1.5'),('2.7', '1.8');

How can I create a third column with the sum of col1 and col2?

CodePudding user response：

First, create col3 using the ALTER TABLE command.

Then update it with the sums.

UPDATE numbers SET col3 = col1   col2;

CodePudding user response：

I would suggest a calculated column - that way if col1 or col2 are updated, col3 will automatically reflect the correct value; storing mutable data is gnerally not a good idea as it easily leads to inconsistencies.

alter table Numbers add column col3 float as (col1   col2) stored;

Side note - float is rarely the correct choice of data type, probably you should be using a decimal.