Data types in Oracle

One, scalar data types

1, varchar2 (size) nvarchar2 (size) variable length string

2, char (size) nchar (size) fixed-length string, where n begins with a character set that stores internationalized strings to support multiple languages.
3. Date type

Timesatmp includes up to 9 digits of the decimal point in addition to the date and time

Timesatmp with time zone

Timesatmp with local time zone

The above three data types are only used when developing a database system with a higher time requirement.

4. Number (p,s) numeric data type

5. LOB type objects for processing multimedia data types

BLOBs are used to store large, unstructured binary data objects, such as photo slideshows, in a database

CLOB and NCLOB are used to store fixed-length bytes of big data objects such as speeches and resumes, where NCLOB stores fixed-length national language character set data

Note: Some operations in CLOB and BLOB columns cannot be done directly using Oracle's database commands, so Oracle provides DBMS_LOB Plsql packages to maintain the LOB data type columns

6. Bfile is used to store large unstructured binary objects in operating system files outside the database system. The bfile data type is an external data type, so columns defined as BFILE data types cannot be manipulated by Oracle database commands, which can only be maintained by operating system commands and third-party software

7. Raw binary data stored directly in the database

Ii. Collection Data types

1. Collection data type

Varray variable-length array type defines a variable-length array that is stored in the column

The data stored in the column defined by the nested table type is itself a data table

III. Relational data types

1. Relational data type ref

Data bits stored in columns defined by the REF data type one address (pointer) to another data row, which speeds up the connection speed of the two tables. But at this point they are not relational models but have morphed into hierarchical models.

Data types in Oracle