SELECT
    base.skaititajs_numurs,
    base.objekts_nosaukums,
    base.pedejais_datums,
    base.pedeja_vertiba,
    prev.prieksejais_datums,
    prev.priekseja_vertiba,
    (base.pedeja_vertiba - prev.priekseja_vertiba) AS pieaugums
FROM (
    -- Latest reading per counter
    SELECT
        md.number AS skaititajs_numurs,
        mot.old_name AS objekts_nosaukums,
        md.date AS pedejais_datums,
        md.value AS pedeja_vertiba
    FROM metter_data md
    JOIN metter_meter mm ON md.number = mm.number
    JOIN metter_object_temp mot ON mm.id = mot.object_id
    WHERE (md.number, md.date) IN (
        SELECT md2.number, MAX(md2.date)
        FROM metter_data md2
        GROUP BY md2.number
    )
) base
LEFT JOIN (
    -- Second latest reading per counter
    SELECT
        md.number AS skaititajs_numurs,
        md.date AS prieksejais_datums,
        md.value AS priekseja_vertiba
    FROM metter_data md
    WHERE (md.number, md.date) IN (
        SELECT d1.number, MAX(d1.date) AS date
        FROM metter_data d1
        WHERE d1.date < (
            SELECT MAX(d2.date)
            FROM metter_data d2
            WHERE d2.number = d1.number
        )
        GROUP BY d1.number
    )
) prev ON base.skaititajs_numurs = prev.skaititajs_numurs;