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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: 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.
Data types
Every column in a table in a database is assigned a data type. The data type precisely defines the kinds of values that you can store in that column.
Operator Precedence

SQL programming
You can use the HCL Informix® implementation of the SQL language to develop applications for Informix database servers.
- Guide to SQL: Syntax
- 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.
  - System catalog tables
    The system catalog consists of tables and views that describe the structure of the database. Sometimes called the data dictionary, these table objects contain everything that the database knows about itself. Each system catalog table contains information about specific elements in the database. Each database has its own system catalog.
  - Data types
    Every column in a table in a database is assigned a data type. The data type precisely defines the kinds of values that you can store in that column.
    - Summary of data types
      HCL Informix® supports the most common set of built-in data types. Additionally, an extended set of data types are supported on the database server.
    - ANSI to Informix data type mapping
    - Description of Data Types
    - Built-In Data Types
    - Extended Data Types
    - Data Type Casting and Conversion
    - Operator Precedence
  - Environment variables
    Various environment variables affect the functionality of your HCL Informix® products. You can set environment variables that identify your terminal, specify the location of your software and define other parameters.
  - Appendixes
- 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.

Operator Precedence

An operator is a symbol or keyword that can be in an SQL expression. Most SQL operators are restricted in the data types of their operands and returned values. Some operators only support operands of built-in data types; others can support built-in and extended data types as operands.

The following table shows the precedence of the operators thatHCL Informix® supports, in descending (highest to lowest) order of precedence. Operators with the same precedence are listed in the same row.


Operator Precedence	Example in Expression
. (membership) [ ] (substring)	customer.phone [1, 3]
UNITS	x UNITS DAY
+ - (unary)	- y
:: (cast)	NULL::TEXT
* /	x / y
+ - (binary)	x -y
\|\| (concatenation)	customer.fname \|\| customer.lname
ANY ALL SOME	orders.ship_date > SOME (SELECT paid_date FROM orders)
NOT	NOT y
< <= = > >= != <>	x >= y
IN BETWEEN ... AND LIKE MATCHES	customer.fname MATCHES y
AND	x AND y
OR	x OR y

See the Informix® Guide to SQL: Syntax for the syntax and semantics of these SQL operators.