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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.
Object-relational databases
Create and use extended data types in Informix®
Complex data types
Collection data types
Nested collection 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.

Nested collection types

A nested collection is a collection type that contains another collection type. You can nest any collection type within another collection type. There is no practical limit on how deeply you can nest a collection type. However, performing inserts or updates on a collection that has been nested more than one or two levels can be difficult.

The following example shows several ways in which you might create columns that are defined on nested collection types:

col_1 SET(MULTISET(VARCHAR(20) NOT NULL) NOT NULL);

col_2 MULTISET(ROW(x CHAR(5), y SET(INTEGER NOT NULL))
NOT NULL);

col_3 LIST(MULTISET(ROW(a CHAR(2), b INTEGER) NOT NULL)
NOT NULL);

For information about how to access a nested collection, see the Informix® Guide to SQL: Tutorial.