Mysql Interview Question and Answers

31. what is difference between primary key and candidate key?
  Primary Key
- are used to uniquely identify each row of the table. A table can have only one primary Key.
Candidate Key
- primary key is a candidate key. There is no difference. By common convention one candidate key is designated as a “primary” one and that key is used for any foreign key references.
32. How do you get the month from a timestamp?
  SELECT MONTH(january_timestamp) from tablename;
33. What do % and _ mean inside LIKE statement?
  % corresponds to 0 or more characters, _ is exactly one character.
34. If you specify the data type as DECIMAL (5,2), what’s the range of values that can go in this table?
  999.99 to -99.99. Note that with the negative number the minus sign is considered one of the digits.
35. How do you get the current date in Mysql?
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