CONVERT VS TRY_CONVERT IN SQL 2012

TRY_CONVERT - It help us to convert to specific data type, it is most similar to CONVERT(). The only difference and advantage is it will return NULL when its fail to convert into given data type. 

Eq.







Open closed document in MS SQL SERVER



We can retrieve the query even we closed our query window in SQL without saving the script.

SELECT execquery.last_execution_time AS [Date Time], execsql.text AS [Script] FROM sys.dm_exec_query_stats AS execquery
CROSS APPLY sys.dm_exec_sql_text(execquery.sql_handle) AS execsql
ORDER BY execquery.last_execution_time DESC

Above query provides a list of scripts and its time of execution in the last 24 hours. 

This will be work for all executed scripts not only a view or procedure.

isNAN function in javascript

isNAN function checks the argument and returns true if the argument is not a number else return false


Example of isNAN()

var val='04cs';

if(isNAN(val))
{
alert('this is not a number') ;
}else{
alert('this is a number') 

}


ANS : this is not a number


var value='0411';

if(isNAN(value))
{
alert('this is not a number') ;
}else{
alert('this is a number') 

}


ANS : this is a number

undefined value and null value

undefined means a variable has been declared but has not yet been assigned a value. On the other hand, null is an assignment value. It can be assigned to a variable as a representation of no value.

Also, undefined and null are two distinct types: undefined is a type itself (undefined) while null is an object.


Unassigned variables are initialized by JavaScript with a default value of undefined. JavaScript never sets a value to null. That must be done programmatically.

undefined check not working in javascript

Checking undefined is not work when we go normal if statement, As like below

var id=$('#txt').val();

if(id != 'undefined')
{
// Our Code
}

"id" is var type, i.e mean unknown type, such as whether "id" is string, numeric, or even undefined.  
if "txt" is not defined in the page, then id's value is  undefined, so we shall check the type of operand with value.

By using "typeof" operator we resolve above issue. The "typeof" operator in JavaScript/Jquery allows you to probe the data type of its operand.

var item = 10;
alert(typeof item); This returns the type of item not value.


if(typeof id != 'undefined')
{
// Our Code


I hope this will help you to resolve the problem.

How to check if a variable is NOT undefined

Checking undefined is not work when we go normal if statement, As like below

var id=$('#txt').val();

if(id != 'undefined')
{
// Our Code
}

"id" is var type, i.e mean unknown type, such as whether "id" is string, numeric, or even undefined.  
if "txt" is not defined in the page, then its value is  undefined is a one of type, so we shall check the type of operand with value.

By using "typeof" operator we resolve above issue. The "typeof" operator in JavaScript/Jquery allows you to probe the data type of its operand.

var item = 10;
alert(typeof item); This returns the type of item not value.


if(typeof id != 'undefined')
{
// Our Code


I hope this will help you to resolve the problem.

find number of days in a month in sql



DECLARE @mydate DATETIME

SET @mydate = '1986/01/21'

SELECT DAY(DATEADD(DAY,-DAY(@mydate),DATEADD(MONTH,1,@mydate))) as DAYSCOUNT


Above query will return number days in a month. Actually it return last date of given month. This is simplest way to get number of days in a given month.