Use This Query to Find Duplicate Rows

Select * from Person

Where Exists(Select 1 from Person A

WHERE Person.FirstName = A.FirstName

ANd Person.LastName = A.LastName

Group BY A.FirstName , A.LastName

Having Count(1)>1)

1 . Use this Query for Getting First Date of Previous Month

SELECT DATEADD(MONTH,-1, DATEADD(DAY,1,DATEADD(DAY,-DAY(GETDATE()),GETDATE())))

2. If you declare numeric(8,6) Means

Sql Allot 2 Digit for Numeric & 6 Digit For Decimal

So increase...

Try This

CASE WHEN [Extension]<80 THEN '0'+ CAST(Extension as VARCHAR(12)) ELSE CAST(Extension as VARCHAR(12)) END AS Extn

hi

Try this

CASE WHEN [Extension]<'80' THEN '0' + CAST( Extension AS varchar(12)) ELSE [Extension] END AS Extn