SQL 面试题与答案
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问题 76. Why does the following command give a compilation error?
DROP TABLE &TABLE_NAME; Variable names should start with an alphabet. Here the table name starts with an '&' symbol.
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问题 77. Which system tables contain information on privileges granted and privileges obtained?
USER_TAB_PRIVS_MADE, USER_TAB_PRIVS_RECD
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问题 78. Which system table contains information on constraints on all the tables created?
USER_CONSTRAINTS.
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问题 79. What is the difference between TRUNCATE and DELETE commands?
TRUNCATE is a DDL command and cannot be rolled back. All of the memory space is released back to the server.
DELETE is a DML command and can be rolled back.
Both commands accomplish identical tasks (removing all data from a table), but TRUNCATE is much faster.
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问题 80. State true or false. !=, <>, ^= all denote the same operation?
True.
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