Date & Time Functions

DuckDB’s temporal scalar functions as free functions in better_duck_diesel::dsl::*.

use diesel::prelude::*;
use better_duck_diesel::dsl::*;

These need the chrono feature for the Rust-side mapping of Date/Time/Timestamp values (or core’s native date_native structs without it). chrono is not on by default in this crate — enable it first.

Extracting parts

Timestamp -> BigInt unless noted: year, month, day, hour, minute, second, epoch(ts) (→Double, seconds since the Unix epoch), date_trunc(part: Text, ts) (→Timestamp, truncate to 'day'/'month'/'hour'/…), strftime(ts, format: Text) (→Text, format a timestamp).

let months: Vec<i64> = events::table.select(month(events::ts)).load(&mut conn)?;

let stamp: String = diesel::select(
    strftime(now_ts, "%Y-%m-%d")
).get_result(&mut conn)?;

Calendar parts and differences

Timestamp -> BigInt unless noted: dayofweek(ts), isodow(ts), dayofyear(ts), weekofyear(ts), quarter(ts), dayname(ts) (→Text), monthname(ts) (→Text), last_day(d: Date) (→Date), datediff(part: Text, start, finish) (→BigInt, whole part units between two timestamps).

let span: i64 = diesel::select(datediff("day", start_ts, end_ts)).get_result(&mut conn)?;

Building dates, times, and timestamps

Function	Signature	Returns
`make_date(year, month, day)`	all `Integer`	`Date`
`make_time(hour, minute, seconds)`	`Integer, Integer, Double`	`Time`
`make_timestamp(micros)`	`BigInt`	`Timestamp`

let d: chrono::NaiveDate = diesel::select(make_date(2026, 1, 15)).get_result(&mut conn)?;

make_timestamp takes microseconds since the Unix epoch, matching DuckDB’s native TIMESTAMP resolution.

Type mapping

DATE / TIME / TIMESTAMP / TIMESTAMPTZ ↔ chrono.

Numeric & utility

Math on the BigInt/Double results.

Feature flags

chrono vs the native date path.

DSL overview

The rest of the DSL.

Getting Started

CRUD

DuckDB SQL DSL

Types & Pooling

Extracting parts

Calendar parts and differences

Building dates, times, and timestamps

See also

Type mapping

Numeric & utility

Feature flags

DSL overview

​Extracting parts

​Calendar parts and differences

​Building dates, times, and timestamps

​See also

Type mapping

Numeric & utility

Feature flags

DSL overview

Extracting parts

Calendar parts and differences

Building dates, times, and timestamps

See also