| The demand of database application which associated with time is rising, so temporal database design becomes a very important problem. With the introduction of temporal dimension, the dates stored in database also become very large. This made the redundant information also increased. Because of this, a problem became very important: how to reduce the redundant information caused by data dependencies effectually. Especially for partially ordered temporal database.First in this paper, introduced the research meaning and background for temporal database and introduced temporal database relevant concepts. Give out function depend consequence rule on partially ordered temporal database. We need to make database standardization for improve the performance of partially ordered temporal database. But, when divide a partially ordered temporal scheme into tense third paradigm (T3NF), some primary attribute part functions depend on the tense candidate keyword can't be eliminated. While in dividing into tense Boyce-Code paradigm (TBCNF) subschema, function dependencies and nondestructive connectivity can't be maintained at the same time. This made us have to research a new paradigm which standardization degrees higher then T3NF but lower then TBCNF. For this purpose, this paper defined partially order temporal elementary keyword normal form (PO-TEKNF). According to relevant theorems and lemma concluded that partially ordered primary keyword normal form decomposition algorithm. And give out prove of the may terminate, keep dependence and nondestructive connectivity for the algorithm.In real application, when creating a relationship, People usually made Tense problem simply for easy to management database. Based on this, the paper puts out the concept of partially ordered within total ordered tenses schema. Given out corresponding definitions and theorems, and based on these corresponding definitions and theorems, give out the partially ordered within total ordered TFD dividing arithmetic (ITOPO-T3NF). Proved terminable and correctness for the arithmetic and give some examples.For design effective mode dividing arithmetic, solve members obscurely is indispensable. Based on partially ordered temporal mode definitions and related derivation rules, this paper give out membership arithmetic for partially ordered schema, and proved validity and correctness for the arithmetic, and analysis time complexity. At the end, this paper discussed covering problems at partially ordered temporal function depends. Introduced defines for covering at partially ordered environment. Put forward partially ordered non-redundancy cover arithmetic, standardization cover arithmetic, make partially ordered database more standardization. |
