单项选择题

Notethefollowingstructuresinyourdatabaseserver：1.Extents2.OSBlocks3.Tablespace4.Segments5.OracleDataBlockWhichoptionhasthecorrectarrangementofthesestructuresfromthesmallesttothelargest（）

A.2，5，1，4，3
B.1，2，3，4，5
C.5，2，1，3，4
D.2，1，5，4，3
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单项选择题
The EMP table contains these columns:EMPLOYEE_ID NUMBER(4)EMPNAME VARCHAR2 (25)SALARY NUMBER(9,2)HIRE_DATE DATEYou query the database with this SQL statement:SELECT empname,hire_date HIREDATE, salaryFROM EMPORDER BY hire_date;How will the results be sorted?（）A.randomlyB.ascending by dateC.descending by dateD.ascending alphabeticallyE.descending alphabetically
A.randomly
B.ascending
C.descending
D.ascending
E.descending
单项选择题
You need to change the definition of an existing tablE.The COMMERCIALS table needs its DESCRIPTION column changed to hold varying length characters up to 1000 bytes. The column can currently hold 500 bytes per valuE.The table contains 20000 rows. Which statement is valid?（）A.ALTER TABLE commercials MODIFY (description CHAR2(1000));B.ALTER TABLE commercials CHANGE (description CHAR2(1000));C.ALTER TABLE commercials CHANGE (description VARCHAR2(1000));D.ALTER TABLE commercials MODIFY (description VARCHAR2(1000));E.You cannot increase the size of a column if the table has rows.
A.ALTER
B.ALTER
C.ALTER
D.ALTER
E.You
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