Oracle column type description

In work, you often need to determine the type of columns in the table according to the actual situation. The following table records the description of column types in oralce.

Field Type	Description	Restrictions	Other Instructions
Char	Fixed-length string	Maximum length: 2000 bytes	Maximum index length: 749
Varchar2	Variable-length string	Maximum length: 4000 bytes
Nchar	Character Set-based fixed-length string	Maximum length: 2000 bytes
Nvarchar2	Variable-length String Based on Character Set	Maximum length: 4000 bytes
Date	Date (day-month-year)	DD-MM-YY (HH-MI-SS) has been strictly tested, no problems
Long	Super long string	A maximum length of 2 GB (231-1) is enough to store big part books.	Multimedia Image sound storage
Raw	Fixed-length binary data	Maximum length: 2000 bytes
Long raw	Variable-length binary data	Maximum length: 2 GB
Blob	Binary data	Maximum length: 4 GB
Clob	Character data	Maximum length: 4 GB
Nclob	Character data based on character sets	Maximum length: 4 GB
Bfile	Binary data stored outside the database	Maximum length: 4 GB
Rowid	Unique row number recorded in the data table	10 bytes	* *******. *****. ***** Format, * 0 or 1
Nrowid	The unique row number recorded in the binary data table.	Maximum length: 4000 bytes
Number (P, S)	Numeric type	P is the integer, and s is the decimal place.
Decimal (P, S)	Numeric type	P is the integer, and s is the decimal place.
Integer	Integer type	Small integer
Float	Floating Point Type	Number (38), Double Precision
Real	Real Number Type	Number (63), higher accuracy