數(shù)據(jù)庫(kù)表的設(shè)計(jì)?案1、?對(duì)多或者多對(duì)?的對(duì)象在數(shù)據(jù)庫(kù)??如何設(shè)置表來(lái)保存數(shù)據(jù)原理解說(shuō)當(dāng)在程序中對(duì)象的關(guān)系為1對(duì)多或者多對(duì)1的關(guān)系時(shí)，在數(shù)據(jù)庫(kù)??我們?cè)鯓釉O(shè)計(jì)表來(lái)保存數(shù)據(jù)呢？(1)?先分別設(shè)計(jì)兩個(gè)表來(lái)保存兩個(gè)對(duì)象的基本屬性，不?管他們之間的關(guān)系(2)然后再在多的對(duì)象的表??設(shè)置外鍵來(lái)描述兩個(gè)表之間數(shù)據(jù)的關(guān)系即可滿?需求?對(duì)多或多對(duì)?的對(duì)象存到數(shù)據(jù)庫(kù)時(shí)，表的設(shè)計(jì)?案部門和員?createtabledepartment(idintprimarykey,namevarchar(40));createtableemployee(idintprimarykey,namevarchar(40),salarydecimal(8,2),department_idint,constraintdepartment_id_FKforeignkey(department_id)referencesdepartment(id));2、多對(duì)多對(duì)象的表的設(shè)計(jì)（?師和學(xué)?）當(dāng)在程序中對(duì)象的關(guān)系為多對(duì)多時(shí)，在數(shù)據(jù)庫(kù)??我們?cè)鯓釉O(shè)計(jì)表來(lái)保存數(shù)據(jù)呢？(1)?先分別設(shè)計(jì)兩個(gè)表來(lái)保存兩個(gè)對(duì)象的基本屬性，不?管他們之間的關(guān)系(2)然后再設(shè)置?個(gè)中間表來(lái)存放兩個(gè)表的主鍵，并把兩個(gè)表的主鍵設(shè)置為這個(gè)中間表的聯(lián)合主鍵，并把它們?cè)O(shè)置為外鍵即可多對(duì)多對(duì)象的表的設(shè)計(jì)（?師和學(xué)?）createtableteacher(idintprimarykey,namevarchar(40),salarydecimal(8,2));createtablestudent(idintprimarykey,namevarchar(40));createtableteacher_student(teacher_idint,student_idint,primarykey(teacher_id,student_id),constraintteacher_id_FKforeignkey(teacher_id)referencesteacher(id),constraintstudent_id_FKforeignkey(student_id)referencesstudent(id));3、?對(duì)?對(duì)象的表的設(shè)計(jì)注意?對(duì)?對(duì)象的關(guān)系?般為主從關(guān)系，如?和?份證的關(guān)系，主可以沒有從，從不能沒有主當(dāng)在程序中對(duì)象的關(guān)系為?對(duì)?時(shí)，在數(shù)據(jù)庫(kù)??我們?cè)鯓釉O(shè)計(jì)表來(lái)保存數(shù)據(jù)呢？(1)?先分別設(shè)計(jì)兩個(gè)表來(lái)保存兩個(gè)對(duì)象的基本屬性，不?管他們之間的關(guān)系(2)然后再在從關(guān)系的表??把主鍵定義外鍵約束即可，注意從關(guān)系的主鍵與主關(guān)系的主鍵是?致的?對(duì)?的對(duì)象的數(shù)據(jù)庫(kù)設(shè)計(jì)createtableperson(idintprimarykey,namevarchar(40));createtableidcard(idintprimarykey,cityvarchar(40),constraintid_FKforeignkey(id)referencesperson(id));4、?關(guān)聯(lián)對(duì)象表的設(shè)計(jì)(1)?先設(shè)計(jì)?個(gè)表來(lái)保存這個(gè)對(duì)象的基本屬性(2)然后再在這個(gè)表的內(nèi)部設(shè)置?個(gè)同類型的外鍵約束即可?連接的表createtableperson(idintprimarykey,namevarchar(40),parent_idint,constraintparent_id_FKforeignkey(parent_id)referencesperson(id));5、?關(guān)聯(lián)對(duì)象練習(xí)題：設(shè)置?個(gè)表來(lái)保存?限極分類6、在實(shí)際