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  • Oracle内置数据类型

    Oracle Built-in Data Types

    The table that follows summarizes Oracle built-in data types. Refer to the syntax in the preceding sections for the syntactic elements. The codes listed for the data types are used internally by Oracle Database. The data type code of a column or object attribute is returned by the DUMP function.

    Table 3-1 Built-in Data Type Summary

    CodeData TypeDescription

    1

    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.

    1

    NVARCHAR2(size)

    Variable-length Unicode character string having maximum length size characters. The number of bytes can be up to two times size for AL16UTF16 encoding and three times sizefor UTF8 encoding. Maximum size is determined by the national character set definition, with an upper limit of 4000 bytes. You must specify size for NVARCHAR2.

    2

    NUMBER [ (p [, s]) ]

    Number having precision p and scale s. The precision p can range from 1 to 38. The scales can range from -84 to 127. Both precision and scale are in decimal digits. A NUMBERvalue requires from 1 to 22 bytes.

    2

    FLOAT [(p)]

    A subtype of the NUMBER data type having precision p. A FLOAT value is represented internally as NUMBER. The precision p can range from 1 to 126 binary digits. A FLOAT value requires from 1 to 22 bytes.

    8

    LONG

    Character data of variable length up to 2 gigabytes, or 231 -1 bytes. Provided for backward compatibility.

    12

    DATE

    Valid date range from January 1, 4712 BC, to December 31, 9999 AD. The default format is determined explicitly by the NLS_DATE_FORMAT parameter or implicitly by theNLS_TERRITORY parameter. The size is fixed at 7 bytes. This data type contains the datetime fields YEARMONTHDAYHOURMINUTE, and SECOND. It does not have fractional seconds or a time zone.

    21

    BINARY_FLOAT

    32-bit floating point number. This data type requires 4 bytes.

    22

    BINARY_DOUBLE

    64-bit floating point number. This data type requires 8 bytes.

    180

    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 theSECOND datetime field. Accepted values of fractional_seconds_precision are 0 to 9. The default is 6. The default format is determined explicitly by the NLS_TIMESTAMP_FORMATparameter or implicitly by the NLS_TERRITORY parameter. The size is 7 or 11 bytes, depending on the precision. This data type contains the datetime fields YEARMONTHDAY,HOURMINUTE, and SECOND. It contains fractional seconds but does not have a time zone.

    181

    TIMESTAMP [(fractional_seconds)] WITH TIME ZONE

    All values of TIMESTAMP as well as time zone displacement value, wherefractional_seconds_precision is the number of digits in the fractional part of the SECONDdatetime field. Accepted values are 0 to 9. The default is 6. The default format is determined explicitly by the NLS_TIMESTAMP_FORMAT parameter or implicitly by theNLS_TERRITORY parameter. The size is fixed at 13 bytes. This data type contains the datetime fields YEARMONTHDAYHOURMINUTESECONDTIMEZONE_HOUR, and TIMEZONE_MINUTE. It has fractional seconds and an explicit time zone.

    231

    TIMESTAMP [(fractional_seconds)] WITH LOCAL TIMEZONE

    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.

    The default format is determined explicitly by the NLS_TIMESTAMP_FORMAT parameter or implicitly by the NLS_TERRITORY parameter. The size is 7 or 11 bytes, depending on the precision.

    182

    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. The size is fixed at 5 bytes.

    183

    INTERVAL DAY [(day_precision)] TO SECOND[(fractional_seconds)]

    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 theSECOND field. Accepted values are 0 to 9. The default is 6.

    The size is fixed at 11 bytes.

    23

    RAW(size)

    Raw binary data of length size bytes. Maximum size is 2000 bytes. You must specify sizefor a RAW value.

    24

    LONG RAW

    Raw binary data of variable length up to 2 gigabytes.

    69

    ROWID

    Base 64 string representing the unique address of a row in its table. This data type is primarily for values returned by the ROWID pseudocolumn.

    208

    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.

    96

    CHAR [(size [BYTE | CHAR])]

    Fixed-length character data of length size bytes or characters. Maximum size is 2000 bytes or characters. Default and minimum size is 1 byte.

    BYTE and CHAR have the same semantics as for VARCHAR2.

    96

    NCHAR[(size)]

    Fixed-length character data of length size characters. The number of bytes can be up to two times size for AL16UTF16 encoding and three times size for UTF8 encoding. Maximumsize is determined by the national character set definition, with an upper limit of 2000 bytes. Default and minimum size is 1 character.

    112

    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).

    112

    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.

    113

    BLOB

    A binary large object. Maximum size is (4 gigabytes - 1) * (database block size).

    114

    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.

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  • 原文地址:https://www.cnblogs.com/liuyuanyuanGOGO/p/datatype.html
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