public static <D extends Comparable> DateExpression<D> datetrunc(DatePart unit, DateExpression<D> expr) {
        return Expressions.dateOperation(expr.getType(), DATE_TRUNC_OPS.get(unit), expr);
    }
Truncate the given date expression

@param unit date part to truncate to
@param expr truncated date
querydsl-sql/src/main/java/com/querydsl/sql/SQLExpressions.java