Working with Dates and Times

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Most host languages do not support the DATE, TIME, and TIMESTAMP data types. Instead, they treat dates as strings or structures. InterBase supports DATE and TIME data types that are stored as single long integers, and a TIMESTAMP data type that is stored in tables as two long integers. An InterBase DATE data type includes information about year, month, and day of the month, the TIME data type includes information about time, and the TIMESTAMP data type is a combination of the two.

This chapter discusses how to SELECT, INSERT, and UPDATE dates from tables in SQL applications using the following isc call interface routines:

  • isc_decode_sql_date() converts the InterBase internal date format to the C time structure.
  • isc_encode_sql_date() converts the C time structure to the internal InterBase date format.
  • isc_decode_sql_time() converts the InterBase internal time format to the C time structure.
  • isc_encode_sql_time() converts the C time structure to the internal InterBase time format.
  • isc_decode_timestamp() converts the InterBase internal timestamp format to the C time structure; this was formerly isc_decode_date().
  • isc_encode_timestamp() converts the C time structure to the InterBase internal timestamp format; this was formerly isc_encode_date().

See the API Guide for a description of each of these functions.

This chapter also discusses how to use the CAST() function to translate DATE, TIME, and TIMESTAMP data types into each other or into CHAR data types and back again, and how to use the DATE literals (YESTERDAY, TOMORROW, NOW, and TODAY) when selecting and inserting dates.

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