SQL INTERVIEW QUESTION & ANSWERS
| 136. |
What is INDEX? |
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INDEX is a general term for an SQL feature used primarily to speed up execution and impose UNIQUENESS upon data. You can use an index to gain fast access to specific information in a database table. An index is a structure that orders the values of one or more columns in a database table. The index provides pointers to the data values stored in specified columns of the table, and then orders those pointers according to the sort order you specify. |
| 137. |
What is meant ny snapshots? |
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- A snapshot is a copy of a table made at a particular time.
- A snapshot is frequently used in a distributed database to create a local copy of a remote table.
- A snapshot is also called a materialized view
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| 138. |
What are the two types of referential triggered actions that can be defined in a FOREIGN KEY constraint? |
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ON UPDATE and ON DELETE |
| 139. |
What are Roles? |
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Roles are named groups of related privileges that are granted to users or other roles. |
| 140. |
What command is used to establish a session? |
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The CONNECT TO statement |
