Every derived table must have its own alias - error when using multiple SELECT statements

问题

I'm trying to use multiple SELECT statements in a query to get data from the database but I get an error. The query is:

SELECT * 
        FROM (SELECT * 
              FROM players 
              WHERE lid = 0)
        WHERE NOT EXISTS (SELECT * 
                          FROM players 
                          WHERE lid = 1)

The error is get is:

Fatal error: Uncaught exception 'PDOException' with message 'SQLSTATE[42000]: Syntax error or access violation: 1248 Every derived table must have its own alias'

I tried changing my query to

SELECT * 
        FROM (SELECT * 
              FROM players 
              WHERE lid = 0)
        WHERE NOT EXISTS (SELECT * 
                          FROM players 
                          WHERE lid = 1) AS T

but got the same error again. I can't understand which part of the query needs an alias and why

回答1:

The from table needs an alias

SELECT * 
        FROM (SELECT * 
              FROM players 
              WHERE lid = 0) as T
        WHERE NOT EXISTS (SELECT * 
                          FROM players 
                          WHERE lid = 1)

Will work

Though the query seems to make no sense. It is not a syntax error anymore

来源：https://stackoverflow.com/questions/36687035/every-derived-table-must-have-its-own-alias-error-when-using-multiple-select-s