ALTER TABLE UserInfo Add (msn varchar2 (20));
1. Build a table
CREATE TABLE UserInfo (
ID Number (6),
Name VARCHAR2 (20),
Sex number (1),
Age Number (3),
Birthday date,
Address VARCHAR2 (50),
Email VARCHAR2 (25),
Tel Number (11)
);
2. Create a constraint
Without a constraint name:
CREATE TABLE UserInfo (
ID Number (6) primary key,--primary key
Name VARCHAR2 () NOT null,--non-null
Sex number (1),
Age Number (3) default 18,
Birthday date,
Address VARCHAR2 (50),
Email varchar2 Unique,--only
Tel Number (11),
Deptno Number (2) References Dept (DEPTNO)-FOREIGN key
With constraint name:
CREATE TABLE UserInfo (
ID number (6) Constraint ID_PK primary key,
Name VARCHAR2 (constraint) name_nn NOT NULL,
Sex number (1),
Age Number (3) default 18,
Birthday date,
Address VARCHAR2 (50),
Email VARCHAR2 (+) constraint Email_uqe unique,
Tel Number (11),
Deptno number (2) Constraint Dept_deptno_ref references dept (DEPTNO)
);
Column mode:
CREATE TABLE UserInfo (
ID Number (6),
Name VARCHAR2 (20),
Sex number (1),
Age Number (3) default 18,
Birthday date,
Address VARCHAR2 (50),
Email VARCHAR2 (25),
Tel Number (11),
Deptno Number (2),
Constraint ID_PK primary key (ID),--can also be more than two, federated primary key
Constraint Dept_deptno_ref foreign KEY (DEPTNO) References Dept (DEPTNO),
Constraint emial_name_uqe Unique (email, name)
);
Alter mode:
ALTER TABLE UserInfo Add (msn varchar2 (20));
ALTER TABLE UserInfo Modify (msn Varchar2 (25));
ALTER TABLE UserInfo drop (MSN);
ALTER TABLE userInfo drop constraint id_pk;
ALTER TABLE USERINFO ADD constraint ID_PK primary key (ID);
3. Create a View
CREATE TABLE V$_dept_view
As
Select Deptno, dname from dept;
--Recompile the view
Alter VIEW V$_dept_view compile;
Tip: A view is typically a query or subquery for a table or multiple tables, which reduces the amount of code, but also increases the level of maintenance of the database view, such as: A table field is deleted or modified, the view is recreated or modified, and a portion of the database is occupied; The view is a virtual table;
4. Create an index
Normal index: CREATE index idx_dpt_dname on dept (Dname);
Federated Index: CREATE index Idx_dept_dname_deptno on dept (Dname, Deptno);
--Unique index
Create unique index idx_emp_ename on scott.emp (ename);
--Reverse Key index
Create INDEX Idx_emp_rev_no on scott.emp (empno) reverse;
--Bitmap Index
Create bitmap index idx_emp_name on scott.emp (dname);
--Index organization table, must have primary key
CREATE Table Tab (
ID int PRIMARY KEY,
Name VARCHAR2 (20)
) organization Index;
--The Insert efficiency of Index Organization table is very low
--Partition Table Index
CREATE index idx_name on table (col) Local/global;
--Index partition
Tip: When you create a primary KEY or UNIQUE key constraint for a table, the system also creates a constraint to that field, and also creates an index that takes up the database space, which improves efficiency when accessing and querying, but slows down when the table is modified;
5. Create a sequence
Create sequence seq;
Select Seq.nextval from dual;
Insert into tab values (Sql.nextval, ' music ');
Create sequence Seqtab
Start with and from 2
Increment by 3-each plus 3
nomaxvalue-No maximum value
MinValue 1-Minimum value 1
Nocycle-does not cycle
nocache;--does not cache
--Modify the sequence, cannot modify the starting value
Alter sequence Seqtab
MaxValue 1000;
6. Create synonyms
A synonym, as the name implies, is an alias or another name.
Create synonym scott_emp for scott.emp;
Create public synonym scott_dept for scott.dept;
SELECT * from Scott_emp;
SELECT * from Scott_dept;
7. CREATE TABLE Space
Create Tablespace Hooms
DataFile ' E:\HooMS.dbf '
Size 5M
Autoextend on next 2M maxsize 10M;
--Create user, assign can manipulate table space
Create user Hoo
Identified by Hoo
Default Tablespace hooms
Temporary tablespace temp;
--Create TABLE space
Create Tablespace myms
DataFile ' c:\myMS.dbf '
Size 1M
Autoextend on;
--scale table space--Modify table space size
ALTER DATABASE
DataFile ' c:\myMS.dbf '
Resize 2M;
--Extension tablespace--Add data file
Alter Tablespace myms
Add datafile ' c:\myMS_2.dbf '
Size 1M;
--Set the DBF file to grow automatically
DataFile ' c:\myMS_2.dbf '
Autoextend on next 2M maxsize 4M;
--Table Space renaming
Alter Tablespace myms
Rename to Hooms;
--Detach table space (offline)
Alter Tablespace Hooms
Offline temporary;
--Offline in archive mode
Alter Tablespace Hooms
Offline immediate;
--Bring the table space online
Alter tablespace hooms Online;
--Delete table spaces with no data
Drop Tablespace hooms;
--Delete table space with data
Drop Tablespace hooms
including contents;
Oracle Notes v. Create tables, constraints, views, indexes, sequences, synonyms, table spaces