Table Reference 

A table reference is a table name with an optional table alias. Table references are used in the FROM clause of a query specification, of the SELECT FOR UPDATE statement and of the SELECT INTO statement. If a table alias has been introduced, the alias must be used in the entire scope of the alias instead of the table name.

Syntax

<table reference> ::= <table name> ( ( AS )? <table alias> )?. <table name> ::= <identifier>. <table alias> ::= <identifier>.

Example

SELECT employee_name FROM employees AS e WHERE e.employee_id = 123

Table Alias.  For the table employees  the alias e is introduced in the FROM clause. This alias has to be used in the WHERE clause instead of the table name.

More Information

FROM Clause