sql create column then add values code example

Example 1: sql add column

ALTER TABLE Customers
ADD Email varchar(255);

Example 2: Insert and initialize a SQL column with value dependent on another column data

UPDATE table
SET col = new_value
WHERE col = old_value
AND other_col = some_other_value;

UPDATE table
SET col = new_value
WHERE col = old_value
OR other_col = some_other_value;