MySQL Interview Question Set 1

1. What is MySQL? 
MySQL is an open source DBMS which is built, supported and distributed by MySQL AB (now acquired by Oracle)

2. What are the technical features of MySQL?
MySQL database software is a client or server system which includes

  • Multithreaded SQL server supporting various client programs and libraries
  • Different backend
  • Wide range of application programming interfaces and
  • Administrative tools.

3. Why MySQL is used?
MySQL database server is reliable, fast and very easy to use. This software can be downloaded as freeware and can be downloaded from the internet.

4. What are Heap tables?
HEAP tables are present in memory and they are used for high speed storage on temporary basis.

  • BLOB or TEXT fields are not allowed
  • Only comparison operators can be used =, <,>, = >,=<
  • AUTO_INCREMENT is not supported by HEAP tables
  • Indexes should be NOT NULL

5. What is the default port for MySQL Server?
The default port for MySQL server is 3306.

6. What are the advantages of MySQL when compared with Oracle?

  • MySQL is open source software which is available at any time and has no cost involved.
  • MySQL is portable
  • GUI with command prompt.
  • Administration is supported using MySQL Query Browser

7. Differentiate between FLOAT and DOUBLE?
Following are differences for FLOAT and DOUBLE:

  • Floating point numbers are stored in FLOAT with eight place accuracy and it has four bytes.
  • Floating point numbers are stored in DOUBLE with accuracy of 18 places and it has eight bytes.

8. Differentiate CHAR_LENGTH and LENGTH?
CHAR_LENGTH is character count whereas the LENGTH is byte count. The numbers are same for Latin characters but they are different for Unicode and other encodings.

9. How to represent ENUMs and SETs internally?
ENUMs and SETs are used to represent powers of two because of storage optimizations.

10. What is the usage of ENUMs in MySQL?
ENUM is a string object used to specify set of predefined values and that can be used during table creation.

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