Oracle field type

Oracle field type

Http://www.cnblogs.com/lihan/archive/2010/01/06/1640547.html

Field type	Describe	Field length and its default value
CHAR (size)	String data used to hold the fixed length (size) byte.	The length of each line is fixed (the insufficient part is blank), the maximum is 2000 bytes per line, and the default value is 1 bytes per line. Consider the character set to be single-byte or multibyte before setting the length (size).
VARCHAR2 (size )	Used to save variable-length string data. Where the maximum byte length is specified by (size).	Each line is variable in length, with a maximum length of 4000 bytes per line. Consider the character set to be single-byte or multibyte before setting the length (size).
NCHAR (size)	The character or byte of a fixed length (size) is determined by the character set.	The length of each line is fixed (the insufficient part is blank). For a fixed-width character set, length (size) refers to the number of characters, and the length (size) is the number of bytes in the width of the character set. The maximum length (size) depends on the length of the bytes held in one character, and the maximum length of each line is 2000 bytes. The default value is 1 characters or 1 bytes, as determined by the character set.
NVARCHAR2 (size )	The character or byte of the variable length is determined by the character set. The maximum length is specified by (size).	Each line becomes longer. For a fixed-width character set, length (size) refers to the number of characters, and the length (size) is the number of bytes in the width of the character set. The maximum length (size) depends on the length of the bytes held in one character, and the maximum length of each line is 4000 bytes. The default value is 1 characters or 1 bytes, as determined by the character set.
LONG	Saves variable-length string data.	The length of each row in the table is variable, with a maximum length of 231-1 bytes per row or 2G.
Number (p, s )	Save the variable length number. Where the maximum value of precision is p, and/or the maximum value of a valid number of digits S is 38.	Each line becomes longer. The maximum length for each row is 21 bytes.
DATE	Save a fixed-length date or time data, in the range of 4712/01/01 BC to A.D. 9999/12/31.	Each row is fixed to a length of 7 bytes, and the default value of the date description (for example, Dd-mon-yy) is set by the Nls_date_format parameter.
RAW (size )	Saves the variable-length binary data. The maximum length is specified by size.	The length of each row in the table is variable, with a maximum length of 2000 bytes per line.
LONG RAW	Saves the variable-length binary data.	The length of each row in the table is variable, with a maximum length of 231-1 bytes per row or 2G.
Blob	Save the binary data.	The maximum length is 232-1 bytes or 4G.
Clob	Saves single-byte character data.	The maximum length is 232-1 bytes or 4G.
NCLOB	Saves the single-byte or fixed-width multibyte or wide multibyte character data specified by the character set.	The maximum length is 232-1 bytes or 4G.
BFILE	Binary data saved in an external file.	The maximum length is 232-1 bytes or 4G.

Char is used to describe fixed-length character data, length <=2000 bytes
VARCHAR2 for describing variable-length character data, <=4000 bytes
NCHAR the fixed-length character data used to store the Unicode character set, length <=1000 bytes
NVARCHAR2 variable-length character data used to store Unicode character sets, length <=1000 bytes
Number is used to store integer or floating-point values
Date used to store data for dates
Long is used to store variable-length character data up to 2GB long
Raw used to store the variable-length character data for unstructured data, length <=2000 bytes
Long Raw is used to store the variable-length character data for unstructured data, length <=2GB
ROWID binary data used to store the physical address of a column in a table, taking up a fixed 10 bytes
BLOBs are used to store up to 4GB of unstructured binary data
Clob used to store up to 4GB of character data
Nclob used to store up to 4GB of Unicode character data
Bfile is used to store unstructured binary data in operating system files other than the database
Urowid used to store binary data representing any type of column address
Float is used to store floating-point numbers

Field type	Chinese description	Restriction conditions	Other instructions
CHAR	Fixed-length strings	Maximum Length 2000	bytes
VARCHAR2	Variable-length strings	Maximum Length 4000	Bytes, maximum length of index can be done 749
NCHAR	Fixed-length strings based on character set	Maximum Length 2000	bytes
NVARCHAR2	Variable-length strings based on character set	Maximum Length 4000	bytes
DATE	Date (day-month-year)	Dd-mm-yy (HH-MI-SS)	After rigorous testing, no problem of thousand worms
LONG	Super Long string	Maximum length 2G (231-1)	Enough to store big data
RAW	Fixed-length binary data	Maximum Length 2000	Bytes can store multimedia image sound, etc.
LONG RAW	Variable-length binary data	Maximum length 2G	Ditto
Blob	Binary data	Maximum length 4G	Greater capacity, ibid.
Clob	Character data	Maximum length 4G
NCLOB	Character data based on the character set	Maximum length 4G
BFILE	Binary data stored outside the database	Maximum length 4G
ROWID	Unique line number recorded in the datasheet	Ten bytes	. ****.**** format, * is 0 or 1
Nrowid	Unique line number recorded in a Binary data table	Maximum Length 4000	bytes
Number (P,s)	Number Type	P is the integer digit, S is the decimal digit
DECIMAL (P,s)	Number Type	P is the integer digit, S is the decimal digit
INTEGER	Integer type	A small integer
FLOAT	Floating-point type	Number (38), double precision
REAL	Real type	Number (63), higher accuracy

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Character Char range Max 2000 byte fixed length
char (10) ' Zhang San ' after adding space 6 to fill 10 bytes of ' Zhang San '
Sex char (2) ' Male '

Varchar2 range maximum 4,000 bytes longer
VARCHAR2 (10) ' Zhang San ' in the database ' Zhang San '

Large object character type large object >4000 byte Max 4G
CLOB (Character Large OBject)

Number range 10-38 square to 10 38-time
You can represent decimals or integers
Number (4) maximum represents 4-bit integer-9999 to 9999
Number (5,2) represents a fraction of 2 decimal places for 5 significant digits-999.99 to 999.99

Date dates include month and day and time Division 7 bytes
Picture blob binary Large object image/sound 4G

Oracle field type