Appendix. Date and Time Types, Operations, and Functions

Each database system has a variety of functions that you can use to calculate or manipulate date and time values. Each database system also has its own rules regarding data types and date and time arithmetic. The SQL Standard specifically defines three functions, CURRENT_DATE(), CURRENT_TIME(), and CURRENT_TIMESTAMP(), but many commercial database systems do not support all three function calls. To help you work with date and time values in your database system, we provide a brief summary of the data types and arithmetic operations supported. Following that, we have compiled a list of functions for several of the major database systems that you can use to work with date and time values. ...

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