Interview QA in PHP

1. What is the REGEXP?

A REGEXP pattern match succeed if the pattern matches anywhere in the value being tested.

2. What is the difference between BLOB AND TEXT?

A BLOB is a binary large object that can hold a variable amount of data. The four BLOB types TINYBLOB, BLOB, MEDIUMBLOB, and LONGBLOB differ only in the maximum length of the values they can hold.
The four TEXT types TINYTEXT, TEXT, MEDIUMTEXT, and LONGTEXT correspond to the four BLOB types and have the same maximum lengths and storage requirements. The only difference between BLOB and TEXT types is that sorting and comparison is performed in case-sensitive fashion for BLOB values and case-insensitive fashion for TEXT values. In other words, a TEXT is a case-insensitive BLOB.

3. How would you change a table to InnoDB?

ALTER TABLE name_file ENGINE innodb;

4. What Is a Session?

Ans.It can be used to store information on the server for future use.

5. 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.