how to use select from in sql code example

Example 1: sql select from select

SELECT t1.*
FROM   t1
WHERE  t1.MY_FIELD = (SELECT  t2.MY_FIELD
                   FROM    t2
                   WHERE   t2.MY_FIELD = t1.MY_FIELD);

Example 2: select in select sql

SELECT column-names  FROM table-name1 WHERE value IN (SELECT column-name                   FROM table-name2                   WHERE condition)