SQL INTERVIEW QUESTION & ANSWERS
| 131. |
What is Transaction? |
| |
Transaction is the execution of user program in DBMS. It is different from
the execution of the program external to DBMS. In other words it can be stated as the various read and write operations done by the user program on the DBMS, when it is executed in DBMS environment. |
| 132. |
What are ACID properties of the DBMS? |
| |
ACID is an acronym for Atomicity, Consistency, Isolation, and Durability.- A – Atomicity
- C – Consistency
- I – Isolation
- D – Durability
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| 133. |
What is a Clustered Index? |
| |
- The data rows are stored in order based on the clustered index key.
- Data stored is in a sequence of the index.
- In a clustered index, the physical order of the rows in the table is the same
as the logical (indexed) order of the key values. - A table can contain only one clustered index.
- A clustered index usually provides faster access to data than does
a non-clustered index
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| 134. |
What is a Non-Clustered Index? |
| |
- The data rows are not stored in any particular order, and there is no particular order to the sequence of the data pages.
- In a clustered index, the physical order of the rows in the table is not same as the logical (indexed) order of the key values.
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| 135. |
Which keywords can you use to combine predicates in a WHERE clause? |
| |
The AND keyword and the OR keyword. |
