Access SQL data types

This section provides an overview of the data types that the supports.

It also describes support for the following types of data:
  • Text and strings
  • Varying-length structures
  • Byte data
  • Miscellaneous SQL data types: POINTER, BOOLEAN, and simple large objects
  • The MI_DATUM structure
  • The NULL constant

For references to discussions of different SQL data types in these topics, see Correspondence of SQL data types to data types.

, C, and SQL data types lists the correspondences between SQL and data types. To declare a variable for an SQL data type, use the appropriate predefined data type or structure for the variable. The mi.h header file includes the header files for the definitions of all data types. Include mi.h in all modules that use data types.
The represents the SQL data type of a column value with the following data type structures:
  • A short name, called the type identifier, which identifies only the data type
  • A long name, called the type descriptor, which provides the data type and information about this type
Server only: Type descriptors and type identifiers do not have an associated memory duration. The allocates them from a special data type cache.