[] brackets in sql statements

Question

What do the brackets do in a sql statement?

For example, in the statement:

insert into table1 ([columnname1], columnname2) values (val1, val2)

Answer 1

The [] marks the delimitation of a identifier, so if you have a column whose name contains spaces like Order Qty you need to enclose it with [] like:

select [Order qty] from [Client sales]

They are also to escape reserved keywords used as identifiers

Answer 2

When having table names or filenames with spaces or dashes (-) etc... you can receive "Systax error in FROM clause". Use [] brackets to solve this.

See: https://msdn.microsoft.com/en-us/library/ms175874.aspx