What's the purpose of SQL keyword “AS”?

Question

You can set table aliases in SQL typing the identifier right after the table name.

SELECT * FROM table t1;

You can even use the keyword

Answer 1

The AS in this case is an optional keyword defined in ANSI SQL 92 to define a < ,commonly known as alias for a table.

 ::=
             [ [ AS ] 
                [    ] ]
          |  [ AS ] 
                [    ]
          | 

      ::=  ::= 

      ::=
           [ {   }... ]


     Syntax Rules

     1) A  immediately contained in a  TR is exposed by TR. A  immediately contained
        in a  TR is exposed by TR if and only if TR
        does not specify a .



It seems a best practice NOT to use the AS keyword for table aliases as it is not supported by a number of commonly used databases.
    

             

                                                        
            
            

              
                
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