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The CUSTOMERS table has these columns: The CUSTOMER_ID column is the primary key for the table.Which two statements find the number of customers? （）
A:SELECT TOTAL(*)   FROM customers;
B:SELECT COUNT(*)   FROM customers;
C:SELECT TOTAL(customer_id)   FROM customers;
D:SELECT COUNT(customer_id)   FROM customers;
E:SELECT COUNT(customers)   FROM customers;
F:SELECT TOTAL(customer_name)   FROM customers;

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出自：Oracle认证

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