Create tables and constraints in Oracle

Creating a table in Oracle focuses on the table field type and corresponding constraints. 1. create table statement Createtabletname (Fied1 Type 1, Fied1 type 2,

Creating a table in Oracle focuses on the table field type and corresponding constraints. 1. Create table statement Create table tname (Fied1 Type 1, Fied1 type 2,

Creating a table in Oracle focuses on the table field type and corresponding constraints.

1. Create a table statement

Create table tname

(

Fied1 Type 1,

Fied1 type 2,

........

);

Create table tname as subquery -- copy existing tables

2. Field Type

Varchar (n) ---- create a field that can store n characters. The data length can be automatically extended. It is compatible with other databases and only occupies two bytes of Chinese characters and full-angle characters, numbers, each English character is a byte;

Varchar2 (n) ---- create a field that can store n characters. The data length can also be increased automatically. It is compatible with other databases. All characters are processed in two bytes (generally ).

Number (n, d) --- create a number. n is an integer, and d is the precision bit.

Date --- create Date Format Field

CLog --- stores large volumes of text

Constraints

Primary key --- Primary key constraint, uniqueness and non-null

Unique ----- uniqueness

Not Null ----- non-Null

Check ------ check and processing sex Check ('M', 'w') restrict the inserted sex field to only two types

Foreign key refrence table (fied) ----- Foreign key, associated with the fied field of the table

Statements for manually creating constraints (except foreign keys) are

Constraint nameconditon (Fild )-----

Statements for manually creating foreign keys

Constraint foreign_name foreign key (fied1) refrence t (f2 );

Modify Table Structure

Alter table tname [Add | Drop | modify] ----- You can Add, delete, or modify table fields.

Related reading:

ORA-02291: violating full constraints (*)-parent keywords not found

Obtain the table storage location and create a tablespace in Oracle

Precautions for creating and inserting tables in Oracle

Oracle creates tablespaces, creates users, authorizes, revokes permissions, deletes users, and deletes tablespaces.

Create Table, prompting ORA-00959: tablespace 'mc _ data' does not exist