# DATE

The `DATE`

data type stores calendar dates with a Year/Month/Day
representation.

## Syntax

`DATE`

## Usage

Storage of `DATE`

variables is based on a 4 byte integer representing
the number of days since 1899/12/31.

The value range is from 0001-01-1 (-693594) to 9999-12-31 (2958464) .

`DATE`

variables are initialized to zero (=1899/12/31) in functions,
modules and globals.

Several built-in functions and operators specific to the `DATE`

type
are available, such as `MDY()`

and `TODAY`

. For more
details, see Date and time operators.

Data type conversions, input and display of `DATE`

values are ruled by
environment settings, such as the DBDATE and DBCENTURY enviroment variables. Dates
can be formatted with the `USING`

operator. For more details, see
Formatting DATE values.

Note: As date-to-string conversion is based on an environment settings, it is not
recommended that you hard code strings representing
dates:

```
LET date_var = "24/12/1998" -- DBDATE dependant code
LET date_var = MDY(12,24,1998) -- Portable code
```

To add or subtract a given number of days to a

`DATE`

, simply use a
`+`

or `-`

arithmetic operator followed by an integer
expression representing a number of days:```
MAIN
DEFINE d DATE
LET d = TODAY
LET d = d + 10 -- Add 10 days
LET d = d - 20 -- Subtract 20 days
DISPLAY "d = ", d USING "yyyy-mm-dd"
END MAIN
```

The difference of two dates returns the number of days:

```
MAIN
DEFINE d1, d2 DATE
LET d1 = MDY(12,24,1998)
LET d2 = MDY(5,11,2010)
DISPLAY "d2 - d1 = ", (d2-d1)
END MAIN
```

`DATE`

values can be converted directly from/to `DATETIME`

values:```
MAIN
DEFINE d DATE,
dt DATETIME YEAR TO FRACTION(3)
LET d = TODAY
LET dt = d; DISPLAY "dt = ", dt
LET dt = CURRENT
LET d = dt; DISPLAY "d = ", d
END MAIN
```

In order to add or subtract a number of months to a

`DATE`

, use the
`UNITS`

operator:```
MAIN
DEFINE d0, d date
LET d0 = MDY(01, 31, 2015)
LET d = d0 + 1 UNITS MONTH; DISPLAY d
LET d = d0 - 1 UNITS MONTH; DISPLAY d
LET d = d0 - 2 UNITS MONTH; DISPLAY d
END MAIN
```

Note: In fact, the

`UNITS`

operator will produce an `INTERVAL`

.
Then the `DATE`

value is converted to a `DATETIME`

, to
add or subtract the `INTERVAL`

value. Finally the `DATETIME`

is converted to a `DATE`

, in order to assign the result to the target variable.