How about:...?

set @companyname = 'A%'

set @companynameOp = 'ne'

set @country = 'Germany'

set @countryOp = 'eq'

set@companyName =

case @companyNameOp

when '' then null

when 'eq' then -- Operator is "equals"

@companyName

when 'bg' then -- Operator is "begins with"

@companyName +'%'

when 'ed' then -- Operator is "ends with"

'%' + @companyName

when 'ct' then -- Operator is "contains"

'%' + @companyName + '%'

set@country =

case @countryOp

when '' then null

when 'eq' then -- Operator is "equals"

@country

when 'bg' then -- Operator is "begins with"

@country +'%'

when 'ed' then -- Operator is "ends with"

'%' + @country

when 'ct' then -- Operator is "contains"

'%' + @country + '%'

-- Ok, now let's form our query.

select

customerid, companyname, country

from

customers

where

(companyName like @companyName or @companyName is null)

AND

(country like @country or @country is null)