Data Type (data_type)

A column definition (column_definition) can contain both the column name (column_name) and data types.

The following data types can be distinguished:

NULL Value
Special NULL Value
Non-NULL values
Character String, LOB Column (CLOB, BLOB), Number, Date Value, Time Value, Time Stamp Value, BOOLEAN

The non-NULL values can be specified using the syntax element data_type.

Structure

Syntax Syntax

<data_type> ::=
  CHAR[ACTER][(<unsigned_integer>)] [ASCII | BYTE | UNICODE]
| VARCHAR[(<unsigned_integer>)] [ASCII | BYTE | UNICODE]
| CLOB [ASCII | UNICODE]
| BLOB
| BOOLEAN
| FIXED(<unsigned_integer> [,<unsigned_integer>])
| FLOAT(<unsigned_integer>)
| INT[EGER]
| SMALLINT
| DATE
| TIME
| TIMESTAMP

End of the code.

For more information on ASCII, BYTE or UNICODE, see the section Code Attribute.

Examples

SQL Tutorial, Tables, Number Generator for a Single Column of a Table

Explanation

In addition to the data types defined above, the following data types are also permitted in a column definition. The table below also indicates the way these are mapped to the above-mentioned data types.

Data Type (data_type)
Data Type	Is Mapped To
BINARY(p)	FIXED(p)
DEC[IMAL](p,s)	FIXED(p,s)
DEC[IMAL](p)	FIXED(p)
DEC[IMAL]	FIXED(5)
DOUBLE PRECISION	FLOAT(38)
FLOAT	FLOAT(16)
FLOAT(39..64)	FLOAT(38)
LONG [ASCII]	CLOB
LONG BYTE	BLOB
LONG UNICODE	CLOB UNICODE
LONG VARCHAR	CLOB
NCHAR(p)	CHAR(p) UNICODE
NCLOB	CLOB UNICODE
NVARCHAR(p)	VARCHAR(p) UNICODE
NUMERIC(p,s)	FIXED(p,s)
NUMERIC(p)	FIXED(p)
NUMERIC	FIXED(5)
REAL(p)	FLOAT(p)
REAL	FLOAT(16)
SERIAL	FIXED(10) DEFAULT SERIAL
SERIAL(p)	FIXED(10) DEFAULT SERIAL(p)

More Information

Memory Requirements of a Column Value According to Data Type

SQL Tutorial, Converting Values