多项选择题
A. You use a NEXTVAL pseudo column to look at the next possible value that would be generated from a sequence, without actually retrieving the value.
B. You use a CURRVAL pseudo column to look at the current value just generated from a sequence, without affecting the further values to be generated from the sequence.
C. You use a NEXTVAL pseudo column to obtain the next possible value from a sequence by actually retrieving the value from the sequence.
D. You use a CURRVAL pseudo column to generate a value from a sequence that would be used for a specified database column.
E. If a sequence starting from a value 100 and incremented by 1 is used by more then one application, then all of these applications could have a value of 105 assigned to their column whose value is being generated by the sequence.
F. You use REUSE clause when creating a sequence to restart the sequence once it generates the maximum value defined for the sequence.
单项选择题 Examine the structure of the EMPLOYEES table: EMPLOYEE_ID NUMBER NOT NULL EMP_NAME VARCHAR2(30) JOB_ID VARCHAR2(20) DEFAULT SA_REP SAL NUMBER COMM_PCT NUMBER MGR_ID NUMBER DEPARTMENT_ID NUMBER You need to update the records of employees 103 and 115. The UPDATE statement you specify should update the rows with the values specified below: JOB_ID: Default value specified for this column definition. SAL: Maximum salary earned for the job ID SA_REP. COMM_PCT: Default value specified for this commission percentage column, if any. If no default value is specified for the column, the value should be NULL. DEPARTMENT_ID: Supplied by the user during run time through substitution variable. Which UPDATE statement meets the requirements?（）
多项选择题 Which three statements about subqueries are true?（）
单项选择题 In a SELECT statement that includes a WHERE clause, where is the GROUP BY clause placed in the SELECT statement?（）