Home
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_value_by_name() functionThe mi_value_by_name() function retrieves a column value from a row, given the column name.

The mi_value_by_name() function

The mi_value_by_name() function retrieves a column value from a row, given the column name.

Syntax

mi_integer mi_value_by_name(row, column_name, retbuf, retlen)
   MI_ROW *row;
   char *column_name;
   MI_DATUM *retbuf;
   mi_integer *retlen;

row: The row from which values are being extracted.
column_name: Name of the column for which the value is to be returned.
retbuf: A pointer to a location in the user space that is set to the address of a buffer that contains the returned value. This function allocates the buffer. You do not need to supply the buffer to contain the returned value.
retlen: The length of the returned column value.


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

Usage

The mi_value_by_name() function returns the value for the column that the column_name column name specifies. It retrieves this column value from the row structure that row references. The only difference between the mi_value_by_name() and mi_value() function is that the former accesses a column by its name while the latter accesses it by column identifier. Like mi_value(), the mi_value_by_name() function is typically called in a loop that terminates when mi_value_by_name() has retrieved values for all the columns in the row.

For more information about how to retrieve values, see the HCL OneDB™ DataBlade® API Programmer's Guide.

Return values

MI_NORMAL_VALUE: The retbuf value is not a row type or a collection. The mi_value_by_name() function places the value in retbuf.
MI_COLLECTION_VALUE: The retbuf value A pointer to a collection structure (MI_COLLECTION).
MI_ROW_VALUE: The retbuf value A pointer to a row structure (MI_ROW).
MI_NULL_VALUE: The retbuf value A NULL value.
MI_ERROR: The function was not successful.