How do i use date_add with postgresql?

PostgreSQL is a powerful, open source Relational Database Management System (RDBMS) that offers users a variety of database features like indexing and advanced SQL commands. The date_add command in PostgreSQL provides a way for users to easily add certain intervals or amounts of time to dates and times.

To use date_add in PostgreSQL, you will have to specify three things: the date field, the time interval that you want to add, and an amount for the interval. For example, if you wanted to add one month to a given date, you would use the following command:

SELECT DATE_ADD(date_field, '1 month', amount) FROM table_name;

This command uses the syntax SELECT … FROM … which is used in all Postgres commands. It specifies that you want to select the results of adding one month (the second argument), and an amount (the third argument), to the specified date field (the first argument).

The unit of time can be based on days ('1 day'), weeks ('1 week'), months ('1 month'), years ('1 year), etc. In addition, the amount field takes an integer value so you can add more than one day or week or whatever unit is specified. For example if we wanted to add two years we could use:

SELECT DATE_ADD(date_field, '2 years', amount) FROM table_name;

You can also subtract from dates by simply prepending '-' before your integer value e.g. '-2 year' or '-5 month' etc.

As well as being able to specify dates as strings e.g. "2018-01-02"; Postgres also allows for several other kinds of formats such as timestamps and even epoch values e.g.:

SELECT DATE_ADD(timestamp '2002-01-21 12:27:20', '3 months', 1);

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