Welcome
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 HCL® 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.
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.
Return Clause
Subset of SQL Data Types
The built-in SQL data types that a user-defined function (UDF) can return are language-dependent.

HCL Informix® V15.0.0 documentation
Welcome to the documentation for HCL Informix® 15.0.0 and related client tools and products.
Product overview
HCL Informix® is a fast and scalable database server that manages traditional relational, object-relational, and dimensional databases. Its small footprint and self-managing capabilities are suited to embedded data-management solutions.
Installing
These topics describe how to install HCL Informix® database servers, client products, and modules.
Administering
In addition to administering the database server, you can tune performance, replicate data, and archive data.
Migrating and upgrading
You can upgrade to the 15.0.0 release of HCL Informix® or migrate from other database servers to Informix. Upgrading is an in-place migration method that uses your existing hardware and operating system software. Some changes to the Informix database server can affect upgrading from a previous release.
Client APIs and tools
You can use the HCL Informix® implementation of client APIs to develop applications for Informix database servers.
Embedding Informix®
When you embed HCL Informix®, you can use enterprise-class high-availability and high performance with embeddability features such as easy programmability, a small disk and memory footprint, and silent deployment.
Extending Informix®
Beyond standard relational database objects, HCL Informix® can be extended to handle specialized data types, access methods, routines, and other objects. Informix includes many built-in extensions that are fully integrated in the database server. Informix also provides modules, which are packages of extended database objects for a particular purpose and that are installed separately from the database server. Alternatively, you can create your own user-defined objects for Informix.
Data warehousing
In addition to designing and implementing Informix® dimensional databases, you can use tools to create data warehouse applications and optimize your data warehouse queries.
Designing databases
The first step in creating a relational database is to construct a data model, which is a precise, complete definition of the data you want to store. After you prepare your data model, you must implement it as a database and tables. To implement your data model, you first select a data type for each column and then you create a database and tables and populate the tables with data. You can also implement fragmentation strategies and control access to your data.
JSON compatibility
You can use the popular JSON-oriented query language created by MongoDB to interact with data stored in HCL Informix®.
Security
You can secure your Informix® database server and the data that is stored in your Informix databases. You can encrypt data, secure connections, control user privileges and access, and audit data security.
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 HCL® 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.
  - 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.
    - Arguments
    - Collection-Derived Table
      A collection-derived table is a virtual table in which the values in the rows of the table are equivalent to elements of a collection. Use this segment where you see a reference to Collection-Derived Table in a syntax diagram. This syntax is an extension to the ANSI/ISO standard for SQL.
    - Database Name
    - Database Object Name
    - External Routine Reference
      Include the External Routine Reference clause when you write an external routine. This option is not available for SPL routines.
    - Identifier
      An identifier specifies the unqualified name of a database object, such as an access method, aggregate, alias, blobspace, cast, column, constraint, correlation, data type, index, operator class, partition, procedure, table, trigger, sequence, synonym, or view. Use the Identifier segment whenever you see a reference to an identifier in a syntax diagram.
    - Jar Name
      Use the Jar Name segment to specify the name of a jar ID. Use this segment whenever you see a reference to Jar Name in a syntax diagram.
    - Optimizer Directives
      The Optimizer Directives segment specifies keywords that you can use to partially or fully specify the query plan of the optimizer. Use this segment whenever you see a reference to Optimizer Directives in a syntax diagram.
    - Owner name
      The owner name specifies the owner of a database object. Use this segment whenever you see a reference to Owner Name in a syntax diagram.
    - Purpose Options
    - Return Clause
      - Limits on Returned Values
      - Subset of SQL Data Types
        The built-in SQL data types that a user-defined function (UDF) can return are language-dependent.
      - Using the REFERENCES Clause to Point to a Simple Large Object
      - Returning a Value from Another Database (IDS)
      - Named Return Parameters (IDS)
      - Cursor and Noncursor Functions
    - Routine modifier
      A routine modifier specifies characteristics of how a user-defined routine (UDR) behaves.
    - Routine Parameter List
    - Shared-Object Filename
      Use a shared-object filename to specify a pathname to an executable object file when you register or alter an external routine.
    - Specific Name
    - Statement Block
  - Built-In Routines
  - Appendixes
- Guide to SQL: Reference
  The HCL® 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 HCL® 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.
Troubleshooting HCL Informix®
Several troubleshooting techniques, tools, and resources are available for resolving problems that you encounter in your HCL Informix® database server environment.

Subset of SQL Data Types

The built-in SQL data types that a user-defined function (UDF) can return are language-dependent.

For more information, see the table that follows. See also Data Type.

UDFs written in a given language can return values of any built-in data type except the types that are marked with an X in the following table.


Data Type	C	Java™	SPL
BIGSERIAL	X	X	X
BLOB	X
CLOB	X
BYTE	X	X
TEXT	X	X
BSON	?	X	?
JSON	?	X	?
COLLECTION		X
LIST		X
MULTISET		X
ROW		X
SET		X
SERIAL	X	X	X
SERIAL8	X	X	X

In Informix®, if you use a complex data type in the Return clause, the calling user-defined routine must define variables of the appropriate complex types to hold the values that the C or SPL user-defined function returns.

User-defined functions can return a value of opaque or distinct data types that are defined in the database.

The default precision of a DECIMAL value that an SPL function returns is 16 digits. For a function to return a DECIMAL with a different number of significant digits, you must specify the returned precision explicitly in the data type specification of the Return clause.