ORACLE中增添删除主键、外键
1、创立表的同时创立主键拘束
1)无命名createtablestudent(studentidintprimarykeyno
ORACLE中增添删除主键、外键
1、创立表的同时创立主键拘束
1)无命名createtablestudent(studentidintprimarykeynotnull,studentnamevarchar(8),ageint);
2)有命名createtablestudents(studentidint,
studentnamevarchar(8),ageint,constraintyyprimarykey(studentid));
2、删除表中已有的主键拘束
(1)无命名可用SELECT*fromuser_cons_columns;查
找表中主键名称得student表中的主键名为SYS_C002715
altertablestudentdropconstraintSYS_C002715;
2)有命名altertablestudentsdropconstraintyy;
3、向表中增添主键拘束altertablestudentaddconstraint
pk_studentprimarykey(studentid);
4、向表中增添外键拘束ALTERTABLEtable_AADD
CONSTRAINTFK_nameFOREIGNKEY(id)
REFERENCEStable_B(id);
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