Management of Oracle Tables

Character type

Char fixed length, Max 2000 characters

char (10) ' xiaoming ', followed by 6 characters will be wasted, suitable for defining fixed-length and frequently queried fields, such as ID number, high efficiency

VARCHAR2 variable length, max 4000 characters

VARCHAR2 (10) ' Xiaoming ' behind 6 character space will be saved

Clob character type large object, Max 4G

Digital type

NUMBER-10 's 38-time-square-38-square

Number (5,2) represents 5 significant digits, with two decimal places -999.99~999.99

Number (5) represents a 5-bit integer

Date type

Date contains the day of the month and seconds

Image

blobs can hold sounds and pictures

Build table

Create TableStudent (--Table nameId Number(4),--School NumberNamevarchar2( -),--nameSexChar(2),--SexBirthday date,--BirthdaySal Number(7,2)--Scholarships)

SELECT  from WHERE PARAMETER = ' Nls_characterset '; If Value=al32utf8  a Chinese character takes 3 bytes, you have to set char (3)

Query table structure

DESC student;

Add Field

Alter Table Add (ClassID number (2));

Modify the length of a field

Delete a field

Alter Table Drop column sal;

Modify Table Name

 to Stu;

Add data

INSERT into student values (' 01 ', ' Zhang San ', ' Male ', ' November-November-82 ', 10000.98);

Management of Oracle Tables