Data types
The smallest unit of data that can be manipulated in SQL is called a value.
How values are interpreted depends on the 
attributes
of
their source, which includes the data type, length, precision, scale,
and CCSID. The sources of values are:
- Columns
- Constants
- Expressions
- Functions
- Special registers
- Variables (such as host variables, SQL variables, global
variables, parameter markers and parameters of routines)
The DB2® relational database products support both built-in data types and user-defined data types. This section describes the built-in data types. For a description of distinct types, see User-defined types.
The following figure illustrates the various built-in data types supported by the DB2 for i program.
For information about specifying the data types of columns, see CREATE TABLE.
- Nulls
All data types include the null value. Distinct from all non-null values, the null value is a special value that denotes the absence of a (non-null) value. - Numbers
The numeric data types are binary integer, decimal, decimal floating-point, and floating-point. - Character strings
A character string is a sequence of bytes. The length of the string is the number of bytes in the sequence. If the length is zero, the value is called the empty string. The empty string should not be confused with the null value. - Character encoding schemes
Each character string is further defined as one of four types. - Graphic strings
A graphic string is a sequence of double-byte characters. The length of the string is the number of its characters. Like character strings, graphic strings can be empty. - Graphic encoding schemes
Each graphic string is further defined as one of two types. - Binary strings
A binary string is a sequence of bytes. Unlike a character string which usually contains text data, a binary string is used to hold non-traditional data such as pictures. The length of a binary string is the number of bytes in the sequence. A binary string has a CCSID of 65535. Only character strings of FOR BIT DATA are compatible with binary strings. - Large objects
The term large object and the generic acronym LOB are used to refer to any CLOB, DBCLOB, or BLOB data type. - Datetime values
Although datetime values can be used in certain arithmetic and string operations and are compatible with certain strings, they are neither strings nor numbers. - XML Values
An XML value represents well-formed XML in the form of an XML document, XML content, or an XML sequence. - DataLink values
A DataLink value is an encapsulated value that contains a logical reference from the database to a file stored outside the database. - Row ID values
A row ID is a value that uniquely identifies a row in a table. A column or a variable can have a row ID data type. A ROWID column enables queries to be written that navigate directly to a row in the table. - User-defined types
A user-defined type is a data type that is defined to the database using a CREATETYPE statement. There
are two types of user-defined type: distinct types and array types.
Parent topic: Language elements