select 8 from tablename

select 8 from tablename,if i wrote like this it will replace all the columns as 8.why it happended.what is the drawback in this.

first of all, doing this will not "replace" anything, because SELECT statements are read only

you are allowed to specify a numeric literal in the SELECT list of columns

so this will return the literal 8 for each row in the table

make sense?