Oracle DML Data Types

Simple Datatypes

Internal Datatypes

• CHAR/NCHAR - fixed length string upto 2000 characters.
• VARCHAR/VARCHAR2/NVARCHAR2 - variable length string upto 4000 characters.
• DATE - fixed length, 7 byte date field. Default format is DD-MON-YY.
• NUMBER (p, s) - p represents precision or number of digits (excluding the decimal point) and s represents scale (number of digits after decimal point). Note that NUMBER declared without precision or scale is a floating point number and NUMBER(p) stores an integer into a floating point number. All numeric data in Oracle7 is stored internally as a modified floating point representation with the datatype NUMBER. A NUMBER datatype is signed (positive or negative), may contain upto 40 decimal digits and ranges from 10^-63 to 10⁺⁶³.
• FLOAT (n) - floating point number of a specified length.
• INTEGER (Oracle7) - an integer.
• SMALLINT (Oracle7) - a short integer.
• LONG - 2Gb variable length field. Superceded by the LOB datatypes.

External Datatypes

The LOB Datatypes

• BLOB - binary large object upto 4Gb for storing binary objects within the database. This is extremely inefficient. Use BFILE instead.
• CLOB - large string object upto 4Gb.
• NCLOB - multibyte character set string object datatype upto 4Gb.
• BFILE - externally stored and internally referenced binary file such as an image.
• RAW (Oracle7) - upto 4000 characters of binary data.Superceded by the LOB datatypes.
• LONG RAW (Oracle7) - binary data upto 2Gb. Superceded by the LOB datatypes.