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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.
Designing and Implementing a Database
The Informix® Database Design and Implementation Guide provides information to help you design, implement, and manage your Informix databases. It includes data models that illustrate different approaches to database design and shows you how to use structured query language (SQL) to implement and manage your databases.
Basics of database design and implementation
Plan a database
Use ANSI-compliant databases
Differences between ANSI-compliant and non-ANSI-compliant databases
Character data types

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.
- Designing and Implementing a Database
  The Informix® Database Design and Implementation Guide provides information to help you design, implement, and manage your Informix databases. It includes data models that illustrate different approaches to database design and shows you how to use structured query language (SQL) to implement and manage your databases.

Character data types

If a database is not ANSI-compliant, you get no error if a character field (CHAR, CHARACTER, LVARCHAR, NCHAR, NVARCHAR, VARCHAR, CHARACTER VARYING) receives a string that is longer than the specified length of the field. The database server truncates the extra characters without resulting in an error message. Thus the semantic integrity of data for a CHAR(n) column or variable is not enforced when the value inserted or updated exceeds n bytes.

In an ANSI-compliant database, you get an error if any character field (CHAR, CHARACTER, LVARCHAR, NCHAR, NVARCHAR, VARCHAR, CHARACTER VARYING) receives a string that is longer than the specified width of the field.