If you are selecting data from table A(with three rows) and table B(with four rows) using "select * from a,b", how many rows will be returned?
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You need to load information about new customers from the NEW_CUST table into the tables CUST and CUST_SPECIAL. If a new customer has a credit limit greater than 10,000, then the details have to be inserted into CUST_SPECIAL. All new customer details have to be inserted into the CUST table. Which technique should be used to load the data most efficiently?
A. external table
B. the MERGE command
C. the multitable INSERT command
D. INSERT using WITH CHECK OPTION
Evaluate the following SQL statement: ALTER TABLE hr.emp SET UNUSED (_id); Which statement is true regarding the effect of the above SQL statement?
Any synonym existing on the EMP table would have to be recreated.
B. Any constraints defined on the MGR_ID column would be removed by the above command.
C. Any views created on the EMP table that include the MGR_ID column would have to be dropped and recreated.
D. Any index created on the MGR_ID column would continue to exist until the DROP UNUSED COLUMNS command is executed.
In which scenario would you use the ROLLUP operator for expression or columns within a GROUP BY clause?
A. to find the groups forming the subtotal in a row
B. to create group wise grand totals for the groups specified within a GROUP BY clause
C. to create a grouping for expressions or columns specified within a GROUP BY clause in one direction, from right to left for calculating the subtotals
D. to create a grouping for expressions or columns specified within a GROUP BY clause in all possible directions, which is cross tabular report for calculating the subtotals
Which two statements are true regarding the execution of the correlated subqueries?(Choose two.) (10分)
A. The nested query executes after the outer query returns the row.
B. The nested query executes first and then the outer query executes.
C. The outer query executes only once for the result returned by the inner query.
D. Each row returned by the outer query is evaluated for the results returned by the inner query.
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