SQL 面试题与答案
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问题 111. What is ROWID?
ROWID is a pseudo column attached to each row of a table. It is 18 characters long, blockno, rownumber are the components of ROWID.
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问题 112. What is the fastest way of accessing a row in a table?
Using ROWID.
CONSTRAINTS
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问题 113. What is an integrity constraint?
Integrity constraint is a rule that restricts values to a column in a table.
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问题 114. What is referential integrity constraint?
Maintaining data integrity through a set of rules that restrict the values of one or more columns of the tables based on the values of primary key or unique key of the referenced table.
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问题 115. What is the usage of SAVEPOINTS?
SAVEPOINTS are used to subdivide a transaction into smaller parts. It enables rolling back part of a transaction. Maximum of five save points are allowed.
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