You will have to suffer with performance issues because of the inability to properly use execution plans with this type of thing unless you can use the dynamic sql approach that Gail suggests.
Something like this.
WHERE
(
(@account = '' OR LEN(@account) = 0 OR @account IS NULL)
AND
(
(Id1 BETWEEN 'AA' AND 'KK' AND Id2 IS NULL)
OR
(Id1 BETWEEN 'MM' AND 'ZZ' AND Id2 IS NOT NULL)
)
)
OR
(
@account > 100
)
The big issue here is that it difficult to decipher the logic. Not too bad when you write it but in 6 months when you have to debug it or the next person comes along it is painful.
Surprising your boss is ok with pass through sql and not dynamic parameterized sql. Many people don't like dynamic sql because they don't understand how to properly protect yourself using parameters.
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