SQL to C: Day-Time Intervals

The identifiers for the day-time interval ODBC SQL data types are:

SQL_INTERVAL_DAY	SQL_INTERVAL_DAY_TO_MINUTE
SQL_INTERVAL_HOUR	SQL_INTERVAL_DAY_TO_SECOND
SQL_INTERVAL_MINUTE	SQL_INTERVAL_HOUR_TO_MINUTE
SQL_INTERVAL_SECOND	SQL_INTERVAL_HOUR_TO_SECOND
SQL_INTERVAL_DAY_TO_HOUR	SQL_INTERVAL_MINUTE_TO_SECOND

The following table shows the ODBC C data types to which day-time interval SQL data may be converted. For an explanation of the columns and terms in the table, see “Converting Data from SQL to C Data Types.”

C type identifier

Test

*TargetValuePtr

*StrLen_or _IndPtr

SQL- STATE

SQL_C_INTERVAL_ DAY [a] SQL_C_INTERVAL_ HOUR [a] SQL_C_INTERVAL_ MINUTE [a] SQL_C_INTERVAL_ SECOND [a] SQL_C_INTERVAL_ DAY_TO_HOUR [a] SQL_C_INTERVAL_ DAY_TO_MINUTE [a] SQL_C_INTERVAL_ DAY_TO_SECOND [a] SQL_C_INTERVAL_ HOUR_TO_MINUTE [a] SQL_C_INTERVAL_ HOUR_TO_SECOND [a] SQL_C_INTERVAL_ MINUTE_TO_ SECOND [a]

Trailing fields portion not truncated Trailing fields portion truncated Leading precision of target is not big enough to hold data from source

Data Truncated data Undefined

Length of data Length of data Undefined

n/a 01S07 22015

SQL_C_STINYINT [b] SQL_C_UTINYINT [b] SQL_C_USHORT [b] SQL_C_SHORT [b] SQL_C_SLONG [b] SQL_C_ULONG [b] SQL_C_NUMERIC [b] SQL_C_BIGINT [b]

Interval precision was a single field and the data was converted without truncation. Interval precision was a single field and truncated fractional. Interval precision was a single field and truncated whole. Interval precision was not a single field.

Data Truncated data Truncated data Undefined

Size of the C data type Length of data Length of data Size of the C data type

n/a 01S07 22003

SQL_C_BINARY

Byte length of data <= BufferLength Byte length of data > BufferLength

Data Undefined

Length of data Undefined

n/a 22003

SQL_C_CHAR

Character byte length < BufferLength Number of whole (as opposed to fractional) digits < BufferLength Number of whole (as opposed to fractional) digits >= BufferLength

Data Truncated data Undefined

Size of the C data type Size of the C data type Undefined

n/a 01004 22003

[a] A day-time interval SQL type can be converted to any day-time interval C type. [b] If the interval precision is a single field (one of DAY, HOUR, MINUTE, or SECOND), then the interval SQL type can be converted to any exact numeric (SQL_C_STINYINT, SQL_C_UTINYINT, SQL_C_USHORT, SQL_C_SHORT, SQL_C_SLONG, SQL_C_ULONG, or SQL_C_NUMERIC).

The default conversion of an interval SQL type is to the corresponding C interval data type. The application then binds the column or parameter (or sets the SQL_DESC_DATA_PTR field in the appropriate record of the ARD) to point to the initialized SQL_INTERVAL_STRUCT structure (or passes a pointer to the SQL_ INTERVAL_STRUCT structure as the TargetValuePtr argument in a call to SQLGetData).

The following example demonstrates how to transfer data from a column of type SQL_INTERVAL_DAY_TO_MINUTE into the SQL_INTERVAL_STRUCT structure such that it comes back as a DAY_TO_HOUR interval.

SQL_INTERVAL_STRUCT is;

SQLINTEGER cbValue;

SQLUINTEGER days, hours;

// Execute a select statement; “interval_column” is a column

// whose data type is SQL_INTERVAL_DAY_TO_MINUTE.

SQLExecDirect(hstmt, “SELECT interval_column FROM table”, SQL_NTS);

// Bind

SQLBindCol(hstmt, 1, SQL_C_INTERVAL_DAY_TO_MINUTE, &is, sizeof(SQL_INTERVAL_STRUCT), &cbValue);

//Fetch

SQLFetch(hstmt);

// Process data

days = is.intval.day_second.day;

hours = is.intval.day_second.hour;