Hi Liigyare1,
Refer the below sample query.
select * from std -- Returns record of all the column from the table
select Id,Name from std -- Returns record of specific column from the table.
Note: I would suggest you to use selected ColumnName in the select statement instead of using * i.e. the 2nd query.
For more details refer below link.
https://msdn.microsoft.com/en-us/library/bb208930%28v=office.12%29.aspx