# TIMESTAMPDIFF

The TIMESTAMPDIFF function returns an estimated number of intervals of the type defined by the first argument, based on the difference between two timestamps.

- numeric-expression
- The first argument must be a built-in data type of either INTEGER
or SMALLINT. The value specifies the interval that is used to determine
the difference between two timestamps. Valid values of the interval
follow.
Table 1. Valid values for numeric-expression and equivalent intervals that are used to determine the difference between two timestamps Valid values for *numeric-expression*Equivalent intervals 1 Microseconds 2 Seconds 4 Minutes 8 Hours 16 Days 32 Weeks 64 Months 128 Quarters 256 Years - string-expression
- string-expression is the result of subtracting
two timestamps and converting the result to a string of length 22. If the
*string-expression*has more than 6 digits to the right of the decimal point, the string will be truncated to 6 digits. The argument must be an expression that returns a value of a built-in character string or a graphic string.If a positive or negative sign is present, it is the first character of the string. The following table describes the elements of the character string duration:Table 2. TIMESTAMPDIFF String Elements String elements Valid values Character position from the decimal point (negative is left) Years 1-9998 or blank -14 to -11 Months 0-11 or blank -10 to -9 Days 0-30 or blank -8 to -7 Hours 0-24 or blank -6 to -5 Minutes 0-59 or blank -4 to -3 Seconds 0-59 -2 to -1 Decimal separator period 0 Microseconds 000000-999999 1 to 6

The result of the function is an integer with the same
sign as *string-expression*. If either argument can be null,
the result can be null; if either argument is null, the result is
the null value.

The returned value is determined for each interval as
indicated by the following table:

Result interval | Computation using duration elements |
---|---|

Years | years |

Quarters | integer value of (months+(years*12))/3 |

Months | months + (years*12) |

Weeks | integer value of ((days+(months*30))/7)+(years*52) |

Days | days + (months*30)+(years*365) |

Hours | hours + ((days+(months*30)+(years*365))*24) |

Minutes (the absolute value of the duration must not exceed 40850913020759.999999) | minutes + (hours+((days+(months*30)+(years*365))*24))*60 |

Seconds (the absolute value of the duration must be less than 680105031408.000000) | seconds + (minutes+(hours+((days+(months*30)+(years*365))*24))*60 )*60 |

Microseconds (the absolute value of the duration must be less than 3547.483648) | microseconds + (seconds+(minutes*60))*1000000 |

The following assumptions are used when converting the element values to the requested interval type:

- One year has 365 days.
- One year has 52 weeks.
- One year has 12 months.
- One quarter has 3 months.
- One month has 30 days.
- One week has 7 days.
- One day has 24 hours.
- One hour has 60 minutes.
- One minute has 60 seconds.
- One second has 1000000 microseconds.

The use of these assumptions imply that some result values
are an estimate of the interval. Consider the following examples:

- Difference of 1 month where the month has less than 30 days.

The result of the timestamp arithmetic is a duration of 00000100000000.000000, or 1 month. When the TIMESTAMPDIFF function is invoked with 16 for the interval argument (days), the assumption of 30 days in a month is applied and the result is 30.`TIMESTAMPDIFF(16, CHAR(TIMESTAMP('1997-03-01-00.00.00') - TIMESTAMP('1997-02-01-00.00.00') ) )`

- Difference of 1 day less than 1 month where the month has less
than 30 days.

The result of the timestamp arithmetic is a duration of 00000027000000.000000, or 27 days. When the TIMESTAMPDIFF function is invoked with 16 for the interval argument (days), the result is 27.`TIMESTAMPDIFF(16, CHAR(TIMESTAMP('1997-03-01-00.00.00') - TIMESTAMP('1997-02-02-00.00.00') ) )`

- Difference of 1 day less than 1 month where the month has 31 days.

The result of the timestamp arithmetic is a duration of 00000030000000.000000, or 30 days. When the TIMESTAMPDIFF function is invoked with 64 for the interval argument (months), the result is 0. The days portion of the duration is 30, but it is ignored because the interval specified months.`TIMESTAMPDIFF(64, CHAR(TIMESTAMP('1997-09-01-00.00.00') - TIMESTAMP('1997-08-02-00.00.00') ) )`

## Example

- The following statement estimates the age of employees in months
and returns that value as AGE_IN_MONTHS:
`SELECT TIMESTAMPDIFF(64, CAST(CURRENT_TIMESTAMP-CAST(BIRTHDATE AS TIMESTAMP) AS CHAR(22))) AS AGE_IN_MONTHS FROM EMPLOYEE`