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Set - 3

Question 1 :

What are the differences between DROP a table and TRUNCATE a table? 

Answer :

DROP TABLE table_name - This will delete the table and its data.

TRUNCATE TABLE table_name - This will delete the data of the table, but not the table definition.


Question 2 :

How do you call a constructor for a parent class?

Answer :

parent::constructor($value)

 


Question 3 :

WHAT ARE THE DIFFERENT TYPES OF ERRORS IN PHP?

Answer :

Here are three basic types of runtime errors in PHP:
1. Notices: These are trivial, non-critical errors that PHP encounters while executing a script - for example, accessing a variable that has not yet been defined. By default, such errors are not displayed to the user at all - although you can change this default behavior. 
2. Warnings: These are more serious errors - for example, attempting to include() a file which does not exist. By default, these errors are displayed to the user, but they do not result in script termination. 
3. Fatal errors: These are critical errors - for example, instantiating an object of a non-existent class, or calling a non-existent function. These errors cause the immediate termination of the script, and PHP's default behavior is to display them to the user when they take place. 
Internally, these variations are represented by twelve different error types


Question 4 :

What's the special meaning of __sleep and __wakeup?

Answer :

__sleep returns the array of all the variables than need to be saved, while __wakeup retrieves them.


Question 5 :

How can we submit a form without a submit button? 

Answer :

If you don't want to use the Submit button to submit a form, you can use normal hyper links to submit a form. But you need to use some JavaScript code in the URL of the link. For example:

<a href="javascript: document.myform.submit();">Submit Me</a>