多项选择题

A. You cannot use the EMP_ID_SEQ sequence to populate t……

Examine the structure of the EMPLOYEES table:
EMPLOYEE_ID NUMBER NOT NULL, Primary Key
EMP_NAME VARCHAR2(30)
JOB_ID NUMBER\
SAL NUMBER
MGR_ID NUMBER References EMPLOYEE_ID column
DEPARTMENT_ID NUMBER Foreign key to DEPARTMENT_ID column of the DEPARTMENTS table You created a sequence called EMP_ID_SEQ in
orderto populate sequential values for the EMPLOYEE_ID column of the EMPLOYEES table. Which two statements regarding the EMP_ID_SEQ sequence are true? （）

A. You cannot use the EMP_ID_SEQ sequence to populate the JOB_ID column.
B. The EMP_ID_SEQ sequence is invalidated when you modify the EMPLOYEE_ID column.
C. The EMP_ID_SEQ sequence is not affected by modifications to the EMPLOYEES table.
D. Any other column of NUMBER data type in your schema can use the EMP_ID_SEQ sequence.
E. The EMP_ID_SEQ sequence is dropped automatically when you drop the EMPLOYEES table.
F. The EMP_ID_SEQ sequence is dropped automatically when you drop the EMPLOYEE_ID column.

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多项选择题Which four are types of functions available in SQL? （）

A. string
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A. difference, projection, join
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A. A MERGE statement is used to merge the data of one table with data from another.
B. A MERGE statement replaces the data of one table with that of another.
C. A MERGE statement can be used to insert new rows into a table.
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A. The UNIQUE constraint does not permit a null value for the column.
B. A UNIQUE index gets created for columns with PRIMARY KEY and UNIQUE constraints.
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