oracle create table(转)

• //建测试表
• create table dept(
• deptno number(3) primary key,
• dname varchar2(10),
• loc varchar2(13)
• );
• create table employee_info(
• empno number(3),
• deptno number(3),
• ename varchar2(10),
• sex char(1),
• phone number(11),
• address varchar2(50),
• introduce varchar2(100)
• );
• --
• //0.重命名
• //0.1 表:rename dept to dt;
• rename dt to dept;
• //0.2 列:alter table dept rename column loc to location;
• alter table dept rename column location to loc;
• //1.添加约束
• //1.1 primary key
• alter table employee_info add constraint pk_emp_info primary key(empno);
• //1.2 foreign key
• alter table employee_info add constraint fk_emp_info foreign key(deptno)
• references dept(deptno);
• //1.3 check
• alter table employee_info add constraint ck_emp_info check
• (sex in ('F','M'));
• //1.4 not null
• alter table employee_info modify phone constraint not_null_emp_info not null;
• //1.5 unique
• alter table employee_info add constraint uq_emp_info unique(phone);
• //1.6 default
• alter table employee_info modify sex char(2) default 'M';
• //2.添加列
• alter table employee_info add id varchar2(18);
• alter table employee_info add hiredate date default sysdate not null;
• //3.删除列
• alter table employee_info drop column introduce;
• //3.修改列
• //3.1 修改列的长度
• alter table dept modify loc varchar2(50);
• //3.2 修改列的精度
• alter table employee_info modify empno number(2);
• //3.3 修改列的数据类型
• alter table employee_info modify sex char(2);
• //3.4 修改默认值
• alter table employee_info modify hiredate default sysdate+1;
• //4.禁用约束
• alter table employee_info disable constraint uq_emp_info;
• //5.启用约束
• alter table employee_info enable constraint uq_emp_info;
• //6.延迟约束
• alter table employee_info drop constraint fk_emp_info;
• alter table employee_info add constraint fk_emp_info foreign key(deptno)
• references dept(deptno)
• deferrable initially deferred;
• //7.向表中添加注释
• comment on table employee_info is 'information of employees';
• //8.向列添加注释
• comment on column employee_info.ename is 'the name of employees';
• comment on column dept.dname is 'the name of department';
• //9.清除表中所有数据
• truncate table employee_info;
• //10.删除表
• drop table employee_info;
• --
• //下面来看看刚刚才我们对表dept和表employee_info所做的更改
• //user_constraints视图里面包含了刚刚才我们创建的所有约束，以及其他信息，
• //你可以用desc user_constraints命令查看其详细说明
• select constraint_name,constraint_type,status,deferrable,deferred
• from user_constraints
• where table_name='EMPLOYEE_INFO';
• --
• CONSTRAINT_NAME                CONSTRAINT_TYPE STATUS   DEFERRABLE     DEFERRED
• ------------------------------ --------------- -------- -------------- ---------
• PK_EMP_INFO                    P               ENABLED  NOT DEFERRABLE IMMEDIATE
• FK_EMP_INFO                    R               ENABLED  DEFERRABLE     DEFERRED
• NOT_NULL_EMP_INFO              C               ENABLED  NOT DEFERRABLE IMMEDIATE
• SYS_C005373                    C               ENABLED  NOT DEFERRABLE IMMEDIATE
• UQ_EMP_INFO                    U               ENABLED  NOT DEFERRABLE IMMEDIATE
• CK_EMP_INFO                    C               ENABLED  NOT DEFERRABLE IMMEDIATE
• //我们可以通过user_cons_columns视图查看有关列的约束信息；
• select owner,constraint_name,table_name,column_name
• from user_cons_columns
• where table_name='EMPLOYEE_INFO';
• --
• OWNER                          CONSTRAINT_NAME                TABLE_NAME                     COLUMN_NAME
• ------------------------------ ------------------------------ ------------------------------ ---------------
• YEEXUN                         PK_EMP_INFO                    EMPLOYEE_INFO                  EMPNO
• YEEXUN                         CK_EMP_INFO                    EMPLOYEE_INFO                  SEX
• YEEXUN                         NOT_NULL_EMP_INFO              EMPLOYEE_INFO                  PHONE
• YEEXUN                         SYS_C005373                    EMPLOYEE_INFO                  HIREDATE
• YEEXUN                         UQ_EMP_INFO                    EMPLOYEE_INFO                  PHONE
• YEEXUN                         FK_EMP_INFO                    EMPLOYEE_INFO                  DEPTNO
• //我们将user_constraints视图与user_cons_columns视图连接起来
• //查看约束都指向哪些列
• column column_name format a15;
• select ucc.column_name,ucc.constraint_name,uc.constraint_type,uc.status
• from user_constraints uc,user_cons_columns ucc
• where uc.table_name=ucc.table_name and
• uc.constraint_name=ucc.constraint_name and
• ucc.table_name='EMPLOYEE_INFO';
• --
• COLUMN_NAME     CONSTRAINT_NAME                CONSTRAINT_TYPE STATUS
• --------------- ------------------------------ --------------- --------
• EMPNO           PK_EMP_INFO                    P               ENABLED
• DEPTNO          FK_EMP_INFO                    R               ENABLED
• PHONE           NOT_NULL_EMP_INFO              C               ENABLED
• HIREDATE        SYS_C005373                    C               ENABLED
• PHONE           UQ_EMP_INFO                    U               ENABLED
• SEX             CK_EMP_INFO                    C               ENABLED
• --
• //这里有个constraint_type，他具体指下面几种类型:
• //C:check,not null
• //P:primary key
• //R:foreign key
• //U:unique
• //V:check option
• //O:read only
• --
• //我们可以通过user_tab_comments视图获得对表的注释
• select * from user_tab_comments
• where table_name='EMPLOYEE_INFO';
• TABLE_NAME                     TABLE_TYPE  COMMENTS
• ------------------------------ ----------- --------------------------
• EMPLOYEE_INFO                  TABLE       information of employees
• --
• //我们还可以通过user_col_comments视图获得对表列的注释：
• select * from  user_col_comments
• where table_name='EMPLOYEE_INFO';
• --
• TABLE_NAME                     COLUMN_NAME                    COMMENTS
• ------------------------------ ------------------------------ ---------------------------
• EMPLOYEE_INFO                  EMPNO
• EMPLOYEE_INFO                  DEPTNO
• EMPLOYEE_INFO                  ENAME                          the name of employees
• EMPLOYEE_INFO                  SEX
• EMPLOYEE_INFO                  PHONE
• EMPLOYEE_INFO                  ADDRESS
• EMPLOYEE_INFO                  ID
• EMPLOYEE_INFO                  HIREDATE
• --
• select * from user_col_comments
• where table_name='EMPLOYEE_INFO' and
• comments is not null;
• --
• TABLE_NAME                     COLUMN_NAME                    COMMENTS
• ------------------------------ ------------------------------ ------------------------
• EMPLOYEE_INFO                  ENAME                          the name of employees
• --
• //最后我们来查看一下修改后的表:
• desc employee_info;
• Name     Type         Nullable Default   Comments
• -------- ------------ -------- --------- ---------------------
• EMPNO    NUMBER(2)
• DEPTNO   NUMBER(3)    Y
• ENAME    VARCHAR2(10) Y                  the name of employees
• SEX      CHAR(2)      Y        'M'
• PHONE    NUMBER(11)
• ADDRESS  VARCHAR2(50) Y
• ID       VARCHAR2(18) Y
• HIREDATE DATE                  sysdate+1
• --
• desc dept;
• Name   Type         Nullable Default Comments
• ------ ------------ -------- ------- ----------------------
• DEPTNO NUMBER(3)
• DNAME  VARCHAR2(10) Y                the name of department
• LOC    VARCHAR2(50) Y