Selecting the table columns you want to query, add to, or update is one way to filter information contained in a table. For example, if you want to display or update the contact name and phone number for each customer ID, it would make sense to select only those columns and omit the columns containing information about the customer's mailing address.
In SQL, the column name is qualified by its table name like this:
tablename.columnname
The SQL Wizard displays the column names using this naming convention. When performing a query, the display lists all the columns belonging to the first table before listing the columns belonging to the second table and so on.
The SQL Wizard also displays an asterisk (*) in the list of available columns. In SQL, the asterisk is the symbol to select all columns in the table(s) and appears like this in a Select statement:
SELECT * FROM tablename
Selecting the asterisk from the list of Available Columns is the same as clicking the All >> button in the SQL Wizard.
