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A smart-large-object data type stores text or binary data in sbspaces. (For information about how to create sbspaces, see your Administrator's Guide.) The database server can provide random access to a smart-large-object value. That is, it can access any portion of the smart-large-object value. These data types are recoverable.
The following table summarizes the smart-large-object data types that Dynamic Server supports.
| Data Type | Purpose |
|---|---|
| BLOB | Stores binary data of up to 4 terabytes (4*240 bytes). |
| CLOB | Stores text data of up to 4 terabytes (4*240 bytes). |
For more information, see the entries for these data types in the Informix Guide to SQL: Reference. For information about the built-in functions you use to import, export, and copy smart large objects, see Smart-Large-Object Functions and the Informix Guide to SQL: Tutorial.
The time data types allow the database server to store increments of time.
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The following table summarizes the time data types available.
User-Defined Data TypeA user-defined data type is a data type that a user defines for the database server.
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Dynamic Server supports the following categories of user-defined data types:
An opaque data type is a user-defined data type that can be used in the same way as a built-in data type. To create an opaque type, you must use the CREATE OPAQUE TYPE statement. Because an opaque type is encapsulated, you create support functions to access the individual components of an opaque type. The internal storage details of the type are hidden, or opaque.
For complete information about how to create an opaque type and its support functions, see Extending Informix Dynamic Server 2000.
A distinct data type is a user-defined data type that is based on an existing built-in type, opaque type, named row type, or distinct type. To create a distinct type, you must use the CREATE DISTINCT TYPE statement. For more information, see the CREATE DISTINCT TYPE statement.
Complex Data TypeComplex data types are data types that you create from built-in types, opaque types, distinct types, or other complex types.
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| Element | Purpose | Restrictions | Syntax |
|---|---|---|---|
| row_type_name | Name of a row type created with the CREATE ROW TYPE statement | The row type must already exist. | Identifier, p. 4-205 Data type, p. 4-53 |
When you create a complex type, you define the components of the complex type. However, unlike an opaque type, a complex type is not encapsulated. You can use SQL to access the individual components of a complex data type.
Dynamic Server supports the following categories of complex data types:
You can assign a named row type to a table or a column. To use a named row type to create a typed table or define a column, the named row type must already exist. To create a named row type, see CREATE ROW TYPE.
An unnamed row type is a group of fields that you create with the ROW constructor. You can use an unnamed row type to define a column. The syntax that you use to define a column as an unnamed row type is shown in the following diagram.
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An unnamed row type is identified by its structure. For the syntax you use to specify row values for an unnamed row type, see Expression.
The syntax you use to define a column as a collection type is shown in the following diagram.
For the syntax you use to specify collection values for a collection data type, see Collection Constructors.
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Privileges on a collection type are those of the column. You cannot specify privileges on specific elements of a collection.
SET Collection TypesA SET is an unordered collection of elements in which each element is unique. You define a column as a SET collection type when you want to store collections whose elements contain no duplicate values and no specific order associated with them.
MULTISET Collection TypesA MULTISET is an unordered collection of elements in which elements can have duplicate values. You define a column as a MULTISET collection type when you want to store collections whose elements might not be unique and have no specific order associated with them.
LIST Collection TypesA LIST is an ordered collection of elements that allows duplicate elements. A LIST differs from a MULTISET in that each element in a LIST collection has an ordinal position in the collection. You define a column as a LIST collection type when you want to store collections whose elements might not be unique but have a specific order associated with them.
Defining the Element TypeThe element type can be any data type except TEXT, BYTE, SERIAL, or SERIAL8. You can nest collection types. That is, an element type can be a collection type.
Every element in the collection must be of the same type. For example, if the element type of a collection type is INTEGER, every element in the collection must be of type INTEGER.
If the element type of a collection is an unnamed row type, the unnamed row type cannot contain fields that hold unnamed row types. That is, a collection cannot contain nested unnamed row types.
When you define a column as a collection type, you must specify that the elements of the collection cannot be null. That is, you must use the NOT NULL keywords after you specify the element type.
For more information about choosing a data type for your database, see the Informix Guide to Database Design and Implementation.
For more information about the specific qualities of individual data types, see the chapter on data types in the Informix Guide to SQL: Reference.
For more information about multi-byte data types, see the discussion of the NCHAR and NVARCHAR data types and the GLS aspects of other character data types in the Informix Guide to GLS Functionality.