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SQL programming
You can use the HCL Informix® implementation of the SQL language to develop applications for Informix database servers.
Guide to SQL: Syntax
The Informix® Guide to SQL: Syntax describes the syntax of the statements, data types, expressions, operators, and built-in functions of the Informix dialect of the SQL language.
Data types and expressions
These topics describe the data types and expressions that Informix®supports.
Data Type
The Data Type segment specifies the data type of a column, of a component of a collection, of a field within a ROW type, of a routine parameter, or of a value returned by an expression or by a cast function. Use this segment whenever you see a reference to a data type in a syntax diagram.
Complex Data Type

SQL programming
You can use the HCL Informix® implementation of the SQL language to develop applications for Informix database servers.
- Guide to SQL: Syntax
  The Informix® Guide to SQL: Syntax describes the syntax of the statements, data types, expressions, operators, and built-in functions of the Informix dialect of the SQL language.
  - Overview of SQL syntax
    These topics provide an overview about how to use the SQL statements, SPL statements, and syntax segments.
  - SQL statements
    This chapter describes the syntax and semantics of SQL statements that are recognized by Informix®.
  - SPL statements
    These topics describe Stored Procedure Language (SPL) statements, which you use to write SPL routines. You can store these routines in the database as user-defined routines (UDRs).
  - Data types and expressions
    These topics describe the data types and expressions that Informix®supports.
    - Scope of Segment Descriptions
    - Use of Segment Descriptions
    - Data type and expression segments
      Data type and expression segments can appear in SQL statements.
    - Collection Subquery
    - Condition
    - Data Type
      The Data Type segment specifies the data type of a column, of a component of a collection, of a field within a ROW type, of a routine parameter, or of a value returned by an expression or by a cast function. Use this segment whenever you see a reference to a data type in a syntax diagram.
      - Built-In Data Types
      - User-Defined Data Type
      - Complex Data Type
        ROW Data Types
        A ROW data type is a complex data type that can store multiple data values within its ordered set of one or more fields. Informix supports two categories of ROW data types: named ROW types that the CREATE ROW TYPE statement registers in the system catalog, and unnamed ROW types that ROW constructor expressions define.
        Collection Data Types
    - DATETIME Field Qualifier
      Use a DATETIME Field Qualifier to specify the largest and smallest unit of time in a DATETIME column or value. Use this segment whenever you see a reference to a DATETIME Field Qualifier in a syntax diagram.
    - Expression
    - OLAP window expressions
      You can include On-Line Analytical Processing (OLAP) expressions in a SELECT statement to operate on subsets of the rows in the result set of a query or subquery. You can use OLAP window expressions to examine subsets of the qualifying rows for patterns, trends, or exceptions in the data.
    - INTERVAL Field Qualifier
    - Literal Collection
    - Literal DATETIME
      The Literal DATETIME segment specifies a DATETIME value
    - Literal INTERVAL
      The Literal INTERVAL segment specifies a literal INTERVAL value. Use this whenever you see a reference to a literal INTERVAL in a syntax diagram.
    - Literal Number
    - Literal Row
      The Literal Row segment specifies the syntax for literal values of named and unnamed ROW data types.
    - Quoted String
    - Relational Operator
  - Other syntax segments
    These topics describe syntax segments, which are language elements, such as database object names or optimizer directives, that appear as a subdiagram reference in the syntax diagrams of some SQL or SPL statements.
  - Built-In Routines
  - Appendixes
- Guide to SQL: Reference
  The Informix® Guide to SQL: Reference contains the reference information for the system catalog tables, data types, and environment variables of the HCL Informix dialect of the SQL language, as implemented in HCL Informix. These topics also include information about the stores_demo, sales_demo, and superstore_demo databases that are included with HCL Informix.
- Guide to SQL: Tutorial
  The Informix® Guide to SQL: Tutorial shows how to use basic and advanced structured query language (SQL) to access and manipulate the data in your databases. It discusses the data manipulation language (DML) statements as well as triggers and stored procedure language (SPL) routines, which DML statements often use.

Complex Data Type

Complex data types are ROW types or COLLECTION types that you create from built-in types, opaque types, distinct types, or other complex types.

^{(explicit id cdty001)
cdty001} ^{(explicit id cdty002)
cdty002}

Complex Data Type

{ <Row Data Types>^[] | <Collection Data Types>^[] }

A single complex data type can include multiple components. When you create a complex type, you define the components of the complex type. Unlike an opaque type, however, a complex type is not encapsulated. You can use SQL to access the individual components of a complex data type. The individual components of a complex data type are called elements.

Informix® supports the following categories of complex data types:

ROW data types: Named ROW types and unnamed ROW types
COLLECTION data types: SET, MULTISET, and LIST

The elements of a COLLECTION data type must all be of the same data type. You can use the keyword COLLECTION in SPL data type declarations to specify an untyped collection variable. NULL values are not supported in elements of COLLECTION data types.

The elements of a ROW data type can be of different data types, but the pattern of data types from the first to the last element cannot vary for a given ROW data type. NULL values are supported in elements of ROW data types, unless you specify otherwise in the data type declaration or in a constraint.

¹ See CREATE ROW TYPE statement

² See Collection Data Types