Dynamic Where Clause

Hi,
According to input my column changes in where condition.
I tried it gives an error.
in the else part ELSE CountryID = @CountryID
Msg 102, Level 15, State 1, Line 16
Incorrect syntax near '='.
If i removed the else part ELSE CountryID = @CountryID
I got this error.
Msg 4145, Level 15, State 1, Line 18
An expression of non-boolean type specified in a context where a condition is expected, near 'END'.

DECLARE @PropertyName VARCHAR(100)
DECLARE @PropertyID VARCHAR(10)
DECLARE @CountryID INT

BEGIN

SET @PropertyName = ' '
SET @PropertyID = '56'
SET @CountryID = 3

SELECT * FROM vw_BasicSearch
WHERE

CASE
WHEN ( ISNULL(@PropertyName, ' ') != ' ' AND ISNULL(@PropertyID, ' ') != ' ') THEN ' PropertyName @PropertyName AND PropertyID = @PropertyID'
ELSE CountryID = @CountryID
END
END
Help me to over come this problem.
Thanks in advance

CASE is an expression, not an operator. It returns a value, it does not control the flow!
So you can use it like ...
WHERE column = CASE WHEN criteria THEN expression1 ELSE expression2 END
****
Actually you're missing the point about dynamic SQL. You cannot have a dynamic WHERE clause in an otherwise static query statement.
The whole query statement must be compiled as a string, and you can then execute the string.

try this
BEGIN
SET @PropertyName = ' '
SET @PropertyID = '56'SET @CountryID = 3SELECT * FROM vw_BasicSearch WHERE (( ISNULL(@PropertyName, ' ') != ' '
AND ISNULL(@PropertyID, ' ') != ' ') AND PropertyID = @PropertyID)or(( ISNULL(@PropertyName, ' ') ' '
or ISNULL(@PropertyID, ' ') != ' ') AND CountryID = @CountryID)END