Adding a new empty column to sql select query

Question

i have the following sql select query

select column1,column2 from mytable

is a way to add an empty column to the query that doesnt exist in the table such as

select column1,column2,empty int column from mytable

Answer 1

你可以这样做

select column1,column2,1 as column3 from mytable

Answer 2

w3 Schools has a good section on this SQL Alter Table Statement .

The specific command would ALTER TABLE table_name ADD column_name datatype

While it does not add the column in a select statement I believe this will accomplish what you are looking for.