通过客户端连接数据库，进行相应的操作
一、访问方式：SQL Plus ; PL Sql Developer
以system帐户连接数据库，链接标识符是:orcl
1. 通过SQL Plus 连接访问数据库
两种方式：web访问 通过菜单直接进入命令行窗口2.打开PL/SQL Developer，FILE->new-->SQL Window二、新建对象
创建用户及表如一个用户名为school 密码为school的用户帐户:
Create user school Identified by school; 为school用户分配：连接到数据库的权限、在自己的模式中创建对象的权限。 Grant create session,resource to school; 创建表 Oracle常用的字段类型有 CHAR 固定长度的字符串 VARCHAR2 可变长度的字符串 NUMBER(M,N) 数字型M是位数总长度, N是小数的长度 DATE 日期类型 示例： CREATE TABLE "SCHOOL"."STUDENT" ( "SNO" VARCHAR2(9), "SNAME" VARCHAR2(20), "SSEX" VARCHAR2(2), "SAGE" NUMBER, "SDEPT" VARCHAR2(20), PRIMARY KEY ("SNO") VALIDATE ) CREATE TABLE "SCHOOL"."COURSE" ( "CNO" VARCHAR2(4), "CNAME" VARCHAR2(40), "CPNO" VARCHAR2(4), "CCREDIT" NUMBER, PRIMARY KEY ("CNO") VALIDATE , FOREIGN KEY ("CPNO") REFERENCES "SCHOOL"."COURSE" ("CNO") VALIDATE ) CREATE TABLE "SCHOOL"."SC" ( "SNO" VARCHAR2(9), "CNO" VARCHAR2(4), "GRADE" NUMBER, PRIMARY KEY ("SNO", "CNO") VALIDATE , FOREIGN KEY ("SNO") REFERENCES "SCHOOL"."STUDENT" ("SNO") VALIDATE , FOREIGN KEY ("CNO") REFERENCES "SCHOOL"."COURSE" ("CNO") VALIDATE ) 约束状态 enable validate:是默认,新旧数据同时满足约束规则 enable novalidate:旧数据可以不满足,检新插入的数据要满足约束 disable validate:不允许在表上执行任何DML操作,主要用在分区表,对于主键和唯一约事,会删除相应的唯一索引,但约束状态任可用 disable novalidate数据可不满足约束规则,对于主键和唯一约事,会删除相应的唯一索引,三、 查询相关命令，以下是在SQL Plus中执行示例
1）用户 查看当前用户的缺省表空间 SQL>select username,default_tablespace from user_users; 查看当前用户的角色 SQL>select * from user_role_privs; 查看当前用户的系统权限和表级权限 SQL>select * from user_sys_privs; SQL>select * from user_tab_privs; 显示当前会话所具有的权限 SQL>select * from session_privs; 显示指定用户所具有的系统权限 SQL>select * from dba_sys_privs where grantee='GAME'; 2)表 查看用户下所有的表 SQL>select * from user_tables; 查看名称包含log字符的表 SQL>select object_name,object_id from user_objects where instr(object_name,'LOG')>0; 查看某表的创建时间 SQL>select object_name,created from user_objects where object_name=upper('&table_name'); 查看某表的大小 SQL>select sum(bytes)/(1024*1024) as "size(M)" from user_segments where segment_name=upper('&table_name'); 查看放在ORACLE的内存区里的表 SQL>select table_name,cache from user_tables where instr(cache,'Y')>0; 3)索引 查看索引个数和类别 SQL>select index_name,index_type,table_name from user_indexes order by table_name; 查看索引被索引的字段 SQL>select * from user_ind_columns where index_name=upper('&index_name'); 查看索引的大小 SQL>select sum(bytes)/(1024*1024) as "size(M)" from user_segments where segment_name=upper('&index_name'); 4)序列号 查看序列号，last_number是当前值 SQL>select * from user_sequences; 5)视图 查看视图的名称 SQL>select view_name from user_views; 查看创建视图的select语句 SQL>set view_name,text_length from user_views; SQL>set long 2000; 说明：可以根据视图的text_length值设定set long 的大小 SQL>select text from user_views where view_name=upper('&view_name'); 6)同义词 查看同义词的名称 SQL>select * from user_synonyms; 7)约束条件 查看某表的约束条件 SQL>select constraint_name, constraint_type,search_condition, r_constraint_name from user_constraints where table_name = upper('&table_name'); SQL>select c.constraint_name,c.constraint_type,cc.column_name from user_constraints c,user_cons_columns cc where c.owner = upper('&table_owner') and c.table_name = upper('&table_name') and c.owner = cc.owner and c.constraint_name = cc.constraint_name order by cc.position; 8)存储函数和过程 查看函数和过程的状态 SQL>select object_name,status from user_objects where object_type='FUNCTION'; SQL>select object_name,status from user_objects where object_type='PROCEDURE'; 查看函数和过程的源代码 SQL>select text from all_source where owner=user and name=upper('&plsql_name');