摘要：
Constraint NameDescriblePRIMARY KEY主键约束，一张表中即可以有主键也可以没有；如果有，有且只能有一个PRIMARY KEY.FOREIGN KEY外键约束NOT NULL非空约束UNIQUE唯一约束.主键约束，从约束本身来讲就相当于(NOT NULL) + (UNIQUE)CHECK检查约束 阅读全文
摘要：
SynonymCreating a Synonym for an Object Simplify access to objects by creating a synonym(another name for an object).With synonyms ,you can：Create an easier reference to a table that is owned by another user Shorten length object namesCREATE [PUBLIC] SYNONYM synonym FRO object; PUBLIC关键词，如果指定了，则全局都可 阅读全文
摘要：
Indexes是可选项，可有可无；它存在的价值就是improves the performance of some queries.An index:Is a schema object Can be used by the Oracle server to speed up the retrieval of rows by using a pointerCan reduce disk input/output(I/O) by using a rapid path access method to locate data quicklyIs independent of the table t 阅读全文
摘要：
Data TypeDescriptionVARCHAR2(size)Variable-length character dataCHAR(size)Fixed-length character dataNUMBER(p,s)Variable-length numeric dataDATEDate and time valuesLONGVariable-length character data(up to 2G);Oracle推荐不使用此数据类型,推荐使用CLOB、BLOBCLOBCharacter data(up to 4GB)RAW and LONG RAWRaw binary dataB 阅读全文
摘要：
ObjectivesAfter completing this lesson,you should be able to do the following:Categorize the main database objectsReview the table structureList the data types that are available for columns.Create a simple tableExplain how constraints are created at the time of table creation.Describe how schema ob 阅读全文
摘要：
Oracle Database ObjectsObjectDescribtionTableBasic unit of storage;Composed of rowsViewLogically represents subsets of data from one or more tablesSequenceGenerates numeric valuesIndexImporves the performance of some queriesSynonymGives alternative name to an object 阅读全文