ocp 19c考题，科目082考试题(26) - order by clause

26、Which two statements are true about the ORDER BY clause when used with a SQL statement containing a SET operator such as UNION? (Choose two.)

A. Column positions must be used in the ORDER BY clause

B. Only column names from the first SELECT statement in the compound query are recognized

C. The first column in the first SELECT of the compound query with the UNION operator is used by default to sort output in the absence of an ORDER BY clause

D. Each SELECT statement in the compound query must have its own ORDER BY clause

E. Each SELECT statement in the compound query can have its own ORDER BY clause

source : cuug