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Extending HCL OneDB™Beyond standard relational database objects, HCL OneDB™ can be extended to handle specialized data types, access methods, routines, and other objects. HCL OneDB™ includes many built-in extensions that are fully integrated in the database server. HCL OneDB™ also provides DataBlade® 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 HCL OneDB™.
Creating extensionsYou can create user-defined data types, routines, access methods, and other database objects to suit your needs. You can use application programming interfaces to write user-defined routines and applications that access data in HCL OneDB™ databases.
DataBlade® API Function ReferenceThe HCL OneDB™ DataBlade® API Function Reference describes the DataBlade® API functions and the subset of functions that the DataBlade® API supports.
Function descriptionsThis section gives comprehensive reference information about the functions that are valid within DataBlade® API modules. It lists the function descriptions in alphabetical order, with syntax, usage information, and return values for the functions.
The mi_column_typedesc() functionThe mi_column_typedesc() function obtains the type descriptor of the specified column from a row descriptor.

The mi_column_typedesc() function

The mi_column_typedesc() function obtains the type descriptor of the specified column from a row descriptor.

Syntax

MI_TYPE_DESC *mi_column_typedesc(row_desc, column_id)
   MI_ROW_DESC *row_desc;
   mi_integer column_id;

row_desc: A pointer to the row descriptor of the row that contains the column.
column_id: The column identifier, which specifies the position of the column in the specified row descriptor. Column numbering follows C array-indexing conventions: the first column in the row is at position zero.


Valid in client LIBMI application?	Valid in user-defined routine?
Yes	Yes

Usage

A row descriptor can describe the structure of a row in a table or the structure of a row type. From the row descriptor that row_desc references, the mi_column_typedesc() function obtains the type descriptor of a column for either structure:

The type descriptor for the column at position column_id in the row
The type descriptor for the field at position column_id for the row type

The type descriptor is a DataBlade® API structure that provides information about a data type.

For more information about row descriptors or about type descriptors, see the HCL OneDB™ DataBlade API Programmer's Guide.

Return values

An MI_TYPE_DESC pointer: A pointer to the type descriptor for the specified column or field.
NULL: The function was not successful.