Dynamic Query with AND, OR criteria

I am using Dynamic Query to get the result from my custom table.

I want to execute Dynamic Query with "AND"(&&) as well as with "or"(||) criteria.

SQL which resembles to my need is something like this

Select *开发者_开发问答 
From CustomeTable ct
Where   (ct.firstColumn = "abc" AND ct.secondColumn = "xyz")
        OR ct.thirdColumn = "123";

Please let me know if any knows the solution.

Regards, Tina