An SQL statement passes through 4 stages. They are, Parse, bind, execute and fetch.
o Searches for identical statement in the MEMORY,
o Checks for the syntax, object name and privileges,
o Locks objects used during parse and
o Create and store the execution plan.
o Obtains the values for the any host variables [& or &&],
o Process the statement, and
The optimizer of the server determines the most efficient way to run a SQL statement. This is an important step in the processing of any data manipulation language (DM(Q)L) statement: SELECT, INSERT, UPDATE, MERGE, or DELETE.