Oracle - DataType

1 - About

Each value manipulated by Oracle Database has a datatype.

3 - Type

3.1 - Built-In

Large Object: Oracle - LOB Datatype

Data Type Description
Oracle Database - Character DataType
VARCHAR2(size [BYTE | CHAR]) Variable-length character string having maximum length size bytes or characters. Maximum size is 4000 bytes or characters, and minimum is 1 byte or 1 character. You must specify size for VARCHAR2. BYTE indicates that the column will have byte length semantics; CHAR indicates that the column will have character semantics.
NVARCHAR2(size) Variable-length character string having maximum length size characters. Maximum size is determined by the national character set definition, with an upper limit of 4000 bytes. You must specify size for NVARCHAR2.
LONG Character data of variable length up to 2 gigabytes, or 231 -1 bytes. no more supported
CHAR(size [BYTE | CHAR]) Fixed-length character data of length size bytes. Maximum size is 2000 bytes or characters. Default and minimum size is 1 byte. BYTE and CHAR have the same semantics as for VARCHAR2.
NCHAR(size) Fixed-length character data of length size characters. Maximum size is determined by the national character set definition, with an upper limit of 2000 bytes. Default and minimum size is 1 character.
CLOB A character large object containing single-byte or multibyte characters. Both fixed-width and variable-width character sets are supported, both using the database character set. Maximum size is (4 gigabytes - 1) * (database block size).
NCLOB A character large object containing Unicode characters. Both fixed-width and variable-width character sets are supported, both using the database national character set. Maximum size is (4 gigabytes - 1) * (database block size). Stores national character set data.
Oracle Database - Datatype Datetime
DATE Valid date range from January 1, 4712 BC to December 31, 9999 AD.
TIMESTAMP (fractional_seconds_precision) Year, month, and day values of date, as well as hour, minute, and second values of time, where fractional_seconds_precision is the number of digits in the fractional part of the SECOND datetime field. Accepted values of fractional_seconds_precision are 0 to 9. The default is 6.
TIMESTAMP (fractional_seconds_precision) WITH TIME ZONE All values of TIMESTAMP as well as time zone displacement value, where fractional_seconds_precision is the number of digits in the fractional part of the SECOND datetime field. Accepted values are 0 to 9. The default is 6.
TIMESTAMP (fractional_seconds_precision) WITH LOCAL TIME ZONE All values of TIMESTAMP WITH TIME ZONE, with the following exceptions:
* Data is normalized to the database time zone when it is stored in the database.
* When the data is retrieved, users see the data in the session time zone.
INTERVAL YEAR (year_precision) TO MONTH Stores a period of time in years and months, where year_precision is the number of digits in the YEAR datetime field. Accepted values are 0 to 9. The default is 2.
INTERVAL DAY (day_precision) TO SECOND (fractional_seconds_precision) Stores a period of time in days, hours, minutes, and seconds, where:
* day_precision is the maximum number of digits in the DAY datetime field. Accepted values are 0 to 9. The default is 2.
* fractional_seconds_precision is the number of digits in the fractional part of the SECOND field. Accepted values are 0 to 9. The default is 6.
Oracle Database - Numeric Datatype
NUMBER(p,s) for fixed-point or floating-point number and integer
BINARY_FLOAT for floating-point number
BINARY_DOUBLE for floating-point number
Others
RAW(size) Raw binary data of length size bytes. Maximum size is 2000 bytes. You must specify size for a RAW value.
LONG RAW Raw binary data of variable length up to 2 gigabytes.
ROWID Base 64 string representing the unique address of a row in its table. This datatype is primarily for values returned by the ROWID pseudocolumn.
UROWID [(size)] Base 64 string representing the logical address of a row of an index-organized table. The optional size is the size of a column of type UROWID. The maximum size and default is 4000 bytes.
BLOB A binary large object. Maximum size is (4 gigabytes - 1) * (database block size).
BFILE Contains a locator to a large binary file stored outside the database. Enables byte stream I/O access to external LOBs residing on the database server. Maximum size is 4 gigabytes.

3.2 - user-defined

see CREATE TYPE

4 - Management

4.1 - View

To view the data types contained in a database table, such as the employees table, you can use:

4.2 - Modify

alter table modify column clause

Example:

ALTER schema.table MODIFY COLUMN columnName [datatype] [DEFAULT expr];

5 - Documentation / Reference

db/oracle/datatype.txt · Last modified: 2017/09/06 19:27 by gerardnico