A client-server relational database system, wherein data from the client computer is encrypted by the client computer and hosted by the server computer, the encrypted data is operated upon by the server computer, using one or more operators selected from a group of operators comprising: (a) inequality logic operators, (b) aggregation operators, and (c) wildcard matching operators, to produce an intermediate results set, the intermediate results set is sent from the server computer to the client computer, and the intermediate results set is decrypted and filtered by the client computer to produce actual results. The group of operators is limited because the encrypted results set, when decrypted, includes inaccuracies therein. The client computer applies a set of correction procedures to the decrypted results set to remove the inaccuracies therein.