a column field is a select sql code example

Example 1: how select from db

SELECT columname FROM tablename

Example 2: return columns from table sql

SELECT *
FROM INFORMATION_SCHEMA.COLUMNS -- INFORMATION_SCHEMA is an ANSI-standard (American National Standard Institute) set of read-only views which provide information about all of the tables, views, columns, and procedures in a database
WHERE TABLE_NAME = N'Customers' -- "N" defines the subsequent string (the string after the N) as being in unicode