Data Type Identifiers and Descriptors

The data types listed in the SQL Data Types and C Data Types sections earlier in this appendix are "concise" data types: Each identifier refers to a single data type. There is a one-to-one correspondence between the identifier and the data type. Descriptors, however, do not in all cases use a single value to identify data types. In some cases, they use a "verbose" data type and a type subcode. For all data types except datetime and interval data types, the verbose type identifier is the same as the concise type identifier and the value in SQL_DESC_DATETIME_INTERVAL_CODE is equal to 0. For datetime and interval data types, however, a verbose type (SQL_DATETIME or SQL_INTERVAL) is stored in SQL_DESC_TYPE, a concise type is stored in SQL_DESC_CONCISE_TYPE, and a subcode for each concise type is stored in SQL_DESC_DATETIME_INTERVAL_CODE. Setting one of these fields affects the others. For more information about these fields, see the SQLSetDescField function description.

When the SQL_DESC_TYPE or SQL_DESC_CONCISE_TYPE field is set for some data types, the SQL_DESC_DATETIME_INTERVAL_PRECISION, SQL_DESC_LENGTH, SQL_DESC_PRECISION, and SQL_DESC_SCALE fields are automatically set to default values, as applicable for the data type. For more information, see the description of the SQL_DESC_TYPE field in SQLSetDescField. If any of the default values set is not appropriate, the application should explicitly set the descriptor field through a call to SQLSetDescField.

The following table shows the concise type identifier, verbose type identifier, and type subcode for each datetime and interval SQL and C type identifier. As this table indicates, for datetime and interval data types, the SQL_DESC_TYPE and SQL_DESC_DATETIME_INTERVAL_CODE fields have the same manifest constants both for SQL data types (in implementation descriptors) and for C data types (in application descriptors).

Concise SQL type	Concise C type	Verbose type	DATETIME_INTERVAL_CODE
SQL_TYPE_DATE	SQL_C_TYPE_DATE	SQL_DATETIME	SQL_CODE_DATE
SQL_TYPE_TIME	SQL_C_TYPE_TIME	SQL_DATETIME	SQL_CODE_TIME
SQL_TYPE_TIMESTAMP	SQL_C_TYPE_TIMESTAMP	SQL_DATETIME	SQL_CODE_TIMESTAMP
SQL_INTERVAL_MONTH	SQL_C_INTERVAL_MONTH	SQL_INTERVAL	SQL_CODE_MONTH
SQL_INTERVAL_YEAR	SQL_C_INTERVAL_YEAR	SQL_INTERVAL	SQL_CODE_YEAR
SQL_INTERVAL_YEAR_TO_MONTH	SQL_C_INTERVAL_YEAR_TO_MONTH	SQL_INTERVAL	SQL_CODE_YEAR_TO_MONTH
SQL_INTERVAL_DAY	SQL_C_INTERVAL_DAY	SQL_INTERVAL	SQL_CODE_DAY
SQL_INTERVAL_HOUR	SQL_C_INTERVAL_HOUR	SQL_INTERVAL	SQL_CODE_HOUR
SQL_INTERVAL_MINUTE	SQL_C_INTERVAL_MINUTE	SQL_INTERVAL	SQL_CODE_MINUTE
SQL_INTERVAL_SECOND	SQL_C_INTERVAL_SECOND	SQL_INTERVAL	SQL_CODE_SECOND
SQL_INTERVAL_DAY_TO_HOUR	SQL_C_INTERVAL_DAY_TO_HOUR	SQL_INTERVAL	SQL_CODE_DAY_TO_HOUR
SQL_INTERVAL_DAY_TO_MINUTE	SQL_C_INTERVAL_DAY_TO_MINUTE	SQL_INTERVAL	SQL_CODE_DAY_TO_MINUTE
SQL_INTERVAL_DAY_TO_SECOND	SQL_C_INTERVAL_DAY_TO_SECOND	SQL_INTERVAL	SQL_CODE_DAY_TO_SECOND
SQL_INTERVAL_HOUR_TO_MINUTE	SQL_C_INTERVAL_HOUR_TO_MINUTE	SQL_INTERVAL	SQL_CODE_HOUR_TO_MINUTE
SQL_INTERVAL_HOUR_TO_SECOND	SQL_C_INTERVAL_HOUR_TO_SECOND	SQL_INTERVAL	SQL_CODE_HOUR_TO_SECOND
SQL_INTERVAL_MINUTE_TO_SECOND	SQL_C_INTERVAL_MINUTE_TO_SECOND	SQL_INTERVAL	SQL_CODE_MINUTE_TO_SECOND