how to select all data from a table in sql code example

Example 1: 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

Example 2: sql select

Everything in brackets is optional.
SELECT [all/distinct] <COL1>, <COL2>, <COL3>
FROM <TABLE_NAME>
[JOIN <JOIN_CONDITION>]
[WHERE <CONDITION>]
[GROUP BY <COLUMN_NAME>]
[HAVING <SEARCH_CONDITION>]
[ORDER BY <SORT_SPECIFICATION>]