Obtain normal values

The mi_value() and mi_value_by_name() functions return the MI_NORMAL_VALUE value status for a column with any data type other than a row type or collection. Therefore, these functions return MI_NORMAL_VALUE for columns that have a built-in data type, smart large object, opaque type, or distinct type.

When the mi_value() or mi_value_by_name() function returns MI_NORMAL_VALUE, the contents of the MI_DATUM structure that holds the column value depends on whether the control mode for the query data is text or binary representation, as follows:

Text representation: the MI_DATUM structure contains a pointer to a null-terminated string, which has the text representation of the column value.
Binary representation: the MI_DATUM structure contains a value whose interpretation depends on the passing mechanism used, as follows:
- When mi_value() or mi_value_by_name() passes back a column value to a C UDR, it can pass the value by reference or by value, depending on the data type of the column value. If the function passes back the value by value, the MI_DATUM structure contains the value. If the function passes back the value by reference, the MI_DATUM structure contains a pointer to the value.
- When mi_value() or mi_value_by_name() passes back a column value to a client LIBMI application, it always passes the value by reference. Even for values that you can pass by value in a C UDR (such as an INTEGER value), these functions return the column value by reference. The MI_DATUM structure contains a pointer to the value.

For a list of the text and binary representations of built-in, opaque, and distinct data types, see Table 1.

Important: The difference in behavior of mi_value() and mi_value_by_name() between C UDRs and client LIBMI applications means that row-retrieval code is not completely portable between these two types of DataBlade API modules. When you move your DataBlade API code from one of these uses to another, you must change the row-retrieval code to use the appropriate passing mechanism for column values that mi_value() or mi_value_by_name() returns.