SQL INTERVIEW QUESTION & ANSWERS
| 101. |
What is the purpose of the WHERE clause in an UPDATE statement? |
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The WHERE clause specifies a condition or set of conditions that act as a filter for the rows that are updated. Only the rows that meet the specified conditions are updated. |
| 102. |
What is a VIEW? |
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A View is a database object that is a logical representation of a table. It is derived from a table but has no storage space of its own and often may be used in the same manner as a table. |
| 103. |
Describe Aggregate Functions? |
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SQL provides seven built-in functions to facilitate query processing. The
seven built-in functions are COUNT, MAX, MIN, SUM, AVG, STDDEV and VARIANCE. |
| 104. |
What is a ROWID? |
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ROWID is the logical address of a row, and it is unique within the database. |
| 105. |
What are the steps to design a good database? |
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- First find out the requirements of the user.
- Design a view for each important application
Integrate the views giving the conceptual schema, which is the union of all views
- Map to the data model provided by the DBMS (usually relational)
- Design external views
- Choose physical structures (indexes, etc.)
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