An inventory information system for power plant construction : an emphasis on query support facility | |
| Author | Unchalee Ngaocharoenchitr |
| Call Number | AIT Thesis no. CA-80-12 |
| Subject(s) | Steam power-plants--Design and construction QUERY (Information retrieval system) |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Abstract | This thesis studies a strategy for retrieving information from conventional files using inquiry method to support user's decision-making. A query language is proposed based on the query language SEQUEL. Inverted file organization is chosen for data storage, because the syntax of the query language is such that a query is on Boolean expression of the index terms. To facilitate structured implementation, the logical design of the query processing module is such that it can be decomposed into several independent submodules. A submitted query is processed as follows. First the query is validated for syntax correctness, and then the tuple substitutions submodule is invoked to decompose any nested query into one-variable queries. Using information from the inverted file, predicates in the query expression are then marked as either resolvable or nonresolvable. This procedure results in limiting the number of tuples needed to be scanned and thus reduces I/O times. Consequently, whether a scan list of tuples is produced or the whole relation is to be processed, the tuple is accessed for testing. The testing is done by traversing along predicate nodes of an already constructed test-tree. Finally, required attributes are selected from tuples which satisfy the inquiry condition and are displayed to users through terminal screen or printer. Algorithms of each module are described in full detail. The listing of query program in PL/I together with the result of tested query samples are also included. |
| Year | 1980 |
| Type | Thesis |
| School | School of Engineering and Technology |
| Department | Department of Information and Communications Technologies (DICT) |
| Academic Program/FoS | Computer Application (CA) |
| Chairperson(s) | Krisorn Jittorntrum |
| Examination Committee(s) | Ping Kunawatsatit ; Sharif, M. N. |
| Scholarship Donor(s) | The Government of Japan |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 1980 |