ʶһѵ¡кҹ ( Database System Architecture )

                     ʶһѵ¡к繡ͺѺ͸ԺǤԴǡѺҹŷѺ͸Ժçҧͧкҹ ¤кҹŷءкеͧ仵ͺ кҧккҴ Ҩ繵ͧ ءѡɳеʶһѵ¡ ҧá Ҷʶһѵ¡Ѻкҹǹ ˭ҧ 仵ҵðҹ ˹§ҹ ANSI/SPARC ˹

           ANSI/SPARC Study Group on Data Base Management System ˹§ҹ˹ҷ˹ҵðҹ仢ͧкҹѰ   繡֡ҨѴâŢͧ   American National  Standards Institute / the Standards Planning and Requirements Committee ʹʶһѵ¡ͧкҹū¡   ANSI/SPARC  architecture ´çѺкҹŷҤѡɳҧ ѧ

дѺͧʶһѵ¡

           3 дѺ

1. дѺ ( The Internal Level ) ҧ¡ the physical level дѺ§ѺèѴ纷ҧҾҡش  

2. дѺ¹͡ ( The External Level ) ҧ¡   the user logcal level дѺ§Ѻҡش

3. дѺǤԴ ( The Conceptual Level ) ҧ¡ the community logical levl   ¡   the logcal level дѺҧҧҧͧдѺ

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

дѺ¹͡ ( External Level )

                дѺ¹͡дѺͧФҨ ͼ ҨդѺ͹ ҡá ФҨҤҧѹ Ҩҵླչ C++ , BASIC , PL/I , Java

                ѺشҨͺ ( Query Language ) ੾зҧ Ẻ͡ ͡Ẻҵͧ੾Ѻ˹§ҹ

                Ҥǹ¡ ¢ ( Data Sublanguage : DSL ) Ѻࢵͧ Ҥ鹫觨С˹੾СѺѵСôԹáѺҹҹ Ҩ ¢Ź нѧ ( Embedded ) 㹵 Һҹ ( Host Language ) 觵Һҹз˹ҷѺԴͺ ӹ дǡ㹡觧ҹͧҹŵҧ Ѵͧ÷ͧ, ôԹäӹdz, ºº ͡ 繵

                ¢ŷӤѭѺʹѺʹعкѴðҹǹ˭ ͺԧçҧ SQL ǹ˭Ẻ Ѻ ͺԧçҧ͡Ѻҹ Ҩ·ѧѺ ö¡ЪѴਹǹ˹繤ͺԧçҧѧ Ҷ Ҥѹҧ ( Loosely Coupling ) ¡͡ҡѹҡ Ҷ ҤѹҧṺ ( Lightly Coupling)

                ѡ¢ŨлСͺ仴ҧ 2 ǹ

                1. ҹ ( Data Definition Language : DDL) 繤㹡ûСҧѵ㹰ҹ ͻСçҧҹ

                2. ҨѡԹâ ( Data Manipulation Language : DML) 繤觷ʹѺʹعèѡԹͻż㹰ҹ

          ¹͡Ƕ١˹¡ ҧ¹͡ ( External Schema ) 觻Сͺ¹ҧ ͧ¹¹ͧ͡¹͡ ҧ¹͡ж١¹ҹū㹡óչҧ¡ External DDL

дѺǤԴ ( Conceptual Level )

               ǤԴ繡᷹Ңŷͧҹ ٻẺ繹 ç纺ѹ֡ Ũԧ ҧҾ Ф¢ҧᵡ觨ҡǢͧФ ǤǤԴФͺ ӡѴ ҧǼ

          ǤԴлСͺ仴¹ǤԴ ( Conceptual Record ) » ҨлСͺ ¹ Ἱҧ ¹ѡҹ ¹Ѵ ¹Թ ¹ǤԴ繵ͧ͹Ѻ¹дѺ¹͡ ¹ѹ֡ԧ

         á˹дѺǤԴСз ҧǤԴ ( Conceptual Schema ) Сͺ¹ͧº ҧ ¹ Conceptual DDL 觵ͧ繡á˹ҢͧҹШеͧѺз ҡռšз͡èѴдѺҾ

дѺ ( Internal Level )

           繴᷹ҹŷдѺ çҧ¡աҧ˹ ºѴ ( Stored Record ) 㹹ǡѺ¹Ҿ ¡ Blocks Pages ǡѺػó ҧ

          Ǩж١˹ ҧ ( Internal Level ) 繡á˹ͧ¹ҧ ١Ѵ Ѫշ ҧ㹹¹ Internal DDL

ҧдѺ ( Mappings )

                ʶһѵ¡кҹա§ҹѹա 2 ǹ

                1. ҧдѺǤԴѺдѺ ( Conceptual/Internal Mapping) 繡á˹ʹͧҧдѺǤԴаҹŷѴ çҧͧҹŷѴ纶١¹ ͧ¹ŧ šзҡ¹ŧͧздѺǤԴ ¡դТͧŷҧҾ ( Physical Data Independence )

                2. ҧдѺ¹͡ѺдѺǤԴ ( External/Conceptual Mapping ) 繵ǡ˹ʹͧҧ¹͡ѺǤԴ աûѺ¹дѺǤԴ еͧздѺ¹͡ ա¹ࢵ¹¹ ࢵдѺǤԴ ࢵ 1 ࢵ ( Virtual field ) 觡÷觵ҧ ҹͧ繡úպѧѺ¹͡дѺͧ١з仴 ¡դТͧŷҧá ( Logical Data Independence ) ͧóչСѺ

Ӥѭͧкҹ

                1. зѴѴ ( Compactness ) úѹ֡ŧк红繨ӹǹҡ㹷ǡѹ 硷͹ԡ觻Ѵ鹷 Сҧ͡÷繡д

                2. Ǵ ( Speed ) ͧкҹö鹤׹лѺا繻Ѩغѹ ǡҡ

                3. ˹¹¡ ( Less Drudgery ) 㹡ôѡŷ繡д繧ҹ˹ѡҡҡººѺ硷͹ԡ
кҹŤ

                4. ١ͧ繻Ѩغѹ ( Currency ) ѹкҹŨзբŷ١ͧзѹ еͺӶҵͧ÷Һء

ªͧкҹ ( Benefits of the database approach )

              ªͧкҹ ( Benefits of the database approach ) Դ鹨ҡкҹŷ ͧöǺẺٹ ѧ

           1. кҹöѹ ( The data can be shared ) ҧ кԹ͹ ö¡ʾѡҹҰҹǡѺкâ Ҿ㹵͹·ҹ 繵

             2. кҹöդӫ͹ŧ ( Redundancy can be reduced ) Ŵӫ͹ Ẻ ( Integrated )

           3. кҹŪա§Ŵ褧ͧ ( Inconsistency can be avoided to some extent. )

           4. кҹʹѺʹع÷Ӹá ( Transaction support can de provided ) á 鹵͹÷ӧҹ¡Ԩѹ

          5. кҹöѡҤҾͤ١ͧͧ ( Integrity can be maintained ) ¼ðҹ繼˹ͺѧѺҾ ( DBA implement integrity constraints or business rules. ) â ( DA ) ͺ ͻͧѹ¹ŧ㹰ҹŷ١ͧ Ҩµ㨡

         6. öѧѺҵáѡҤʹ ( Security can be enforced ) Ǥ ðҹö ˹ͺѧѺ ͧʹ ( Security Constraints )

         7. ͧ÷Դҧ öйջй ( conflicting requirements can be balanced. )

         8. öѧѺԴҵðҹ ( Standards can be enforced )

          9. кҹԴТͧ ( Data Independence ) 繻ªӤѭشзѺ᷹ҢԧҾ ( Physical Data Independence )

Тͧ 2 Դ

9.1 зҧҾ ( Physical Data Independence )

9.2 зҧá ( Logical Data Independence )

кҹ ءҴТͧҧ觢

                1. ء줹еǡѹеͧͧ͢ǡѹٻẺᵡҧѹ

                2. ðҹ ͧз¹ŧԸա᷹ҷҧҾ ¹෤Ԥ㹡Ҷ֧ʹͧͺ繷¹ŧ 繵ͧ¹ŧءҧ ѹ

               Тͧ ( Data Independence ) Ԥѹͧء ͡¹ŧ 㹡᷹ŷҧҾС¹ŧ෤ԤҶ֧ ͧѴŧ ա ¹ŧ ѧ ʴءǢͧѺԸա᷹ дѺҾ෤Ԥ Ҷ֧Ը ੾ ¹ԸըҡҶ֧ẺӴѺ 繡Ҷ֧Ẻ Ԩеͧա¹ ء仵෤ԤҶ֧Ẻ ͵çҧèѴ 繵

                ¹ŧðҹ DBA Ҩͧз ѧء ѹͧҹ

•  ࢵ ¹Դͧࢵ

•  º ź ҧ¹

•  ź ¹

              ѡɳТ᷹ͧūҨա¹ŧ¼ðҹ кðҹ ( DBMS ) еͧءԤѹ͡¹ŧҹ

•  ᷹ŵŢ Binary, Decimal

•  ᷹ŵѡ EBCDIC Unicode

•  ˹ͧŵŢ ૹ

•  ŧʢ ¹ҡ Green, Red 1 , 2

•  â ( Data Materialization ) 繡ùҢżҹкǹ ¹Ըա͢鹵͹кǹ ¹Ըաäӹdzٵäӹdz͡ ¹Ըաúǡࢵ

•  çҧ¹ ҡ 2 ¹¹ 1 ¹

 

 

 

 

 

 

• çҧ 㹴ʡ͹ǡѹ ¡͹

             ¹ŧѡɳС᷹Ŵѧǹռšзء¡ Ũҡҹ ҴԸա (¡鹻ԷҾҧ÷ӧҹҨзҧдѺѺ)