Transpose multiple columns for differents tables in SQL

I have the next three tables:

Table A

Table B

Table C

I would want a table like this:

I try the next code:

CREATE TABLE FINAL_TB AS (
                          SELECT CLIENT FROM TABLE_A );

ALTER TABLE FINAL_TB ADD STOCK FLOAT(20);

INSERT INTO FINAL_TB(STOCK) SELECT TABLE_C.STOCK1 FROM TABLE_C 
                            UNION ALL 
                            SELECT TABLE_C.STOCK2 FROM TABLE_C
                            ...
                            UNION ALL 
                            SELECT TABLE_C.STOCK28 FROM TABLE_C;                         

But i don't get the result I want and the code is so extensive. Any help?

I created some temp tables with random values to illustrate:

create table #A
(
    Client int,
    Consumption1 int,
    Consumption2 int,
    Consumption3 int,
    Consumption4 int,
    Consumption5 int,
    Consumption6 int,
    Consumption7 int,
    Consumption8 int,
    Consumption9 int,
    Consumption10 int,
    Consumption11 int,
    Consumption12 int,
    Consumption13 int,
    Consumption14 int,
    Consumption15 int,
    Consumption16 int,
    Consumption17 int,
    Consumption18 int,
    Consumption19 int,
    Consumption20 int,
    Consumption21 int,
    Consumption22 int,
    Consumption23 int,
    Consumption24 int,
    Consumption25 int,
    Consumption26 int,
    Consumption27 int,
    Consumption28 int
)

create table #B
(
    Client int,
    Arrive1 int,
    Arrive2 int,
    Arrive3 int,
    Arrive4 int,
    Arrive5 int,
    Arrive6 int,
    Arrive7 int,
    Arrive8 int,
    Arrive9 int,
    Arrive10 int,
    Arrive11 int,
    Arrive12 int,
    Arrive13 int,
    Arrive14 int,
    Arrive15 int,
    Arrive16 int,
    Arrive17 int,
    Arrive18 int,
    Arrive19 int,
    Arrive20 int,
    Arrive21 int,
    Arrive22 int,
    Arrive23 int,
    Arrive24 int,
    Arrive25 int,
    Arrive26 int,
    Arrive27 int,
    Arrive28 int
)

create table #C
(
    Client int,
    Stock1 int,
    Stock2 int,
    Stock3 int,
    Stock4 int,
    Stock5 int,
    Stock6 int,
    Stock7 int,
    Stock8 int,
    Stock9 int,
    Stock10 int,
    Stock11 int,
    Stock12 int,
    Stock13 int,
    Stock14 int,
    Stock15 int,
    Stock16 int,
    Stock17 int,
    Stock18 int,
    Stock19 int,
    Stock20 int,
    Stock21 int,
    Stock22 int,
    Stock23 int,
    Stock24 int,
    Stock25 int,
    Stock26 int,
    Stock27 int,
    Stock28 int
)

insert into #A values
(4587, 1897163, 1750380, 5487230, 5086290, 3232280, 6014338, 5978823, 5864160, 8462496, 3945424, 6641780, 6268308, 924802, 9246014, 8089559, 6079526, 7332457, 4971714, 379325, 1651062, 5878994, 4987033, 9802665, 8163241, 180040, 3309288, 6966085, 6791869),
(1056, 3693126, 6085435, 2576225, 906414, 9308827, 7912118, 4690652, 2298023, 5333767, 1550576, 3324191, 8750357, 2135258, 3403408, 6807101, 1750717, 8367234, 5176016, 1008922, 9641689, 3564379, 5398274, 4521049, 5767916, 779819, 5466675, 4020480, 7245496),
(8977, 6496397, 7097447, 5026248, 3686617, 4583368, 4018366, 5718120, 318667, 2281474, 4044423, 9424092, 5355506, 7723824, 8635663, 7122301, 3401243, 2478769, 6540496, 8370652, 268827, 8858460, 4468893, 2184993, 416313, 5099858, 170593, 6609073, 7137023)

insert into #B values
(4587, 2667122, 2542268, 1118532, 2284504, 2147917, 1084679, 2729616, 1175793, 2649496, 1699428, 507390, 108714, 828544, 1358961, 1754942, 2084233, 1964319, 1751282, 2047706, 705322, 2918377, 1001676, 1494300, 2937679, 2216776, 2485884, 1217744, 366044),
(1056, 213746, 483120, 1689874, 2063834, 473576, 2063958, 2212633, 819822, 1569991, 1159024, 479248, 495937, 1923624, 1557142, 1164307, 2669944, 2161610, 1187291, 1083194, 1947235, 136211, 1749596, 692847, 1947817, 207300, 2784799, 2061996, 1248644),
(8977, 2085112, 2935995, 1977982, 633723, 2426369, 1156016, 1011041, 470338, 926361, 1244144, 625813, 945190, 1217648, 376607, 89393, 2944627, 1118893, 2939117, 213832, 2269515, 2261478, 1637021, 1961149, 1145781, 206511, 1563378, 1272576, 212847)

insert into #C values
(4587, 806, 797, 310, 784, 411, 629, 966, 134, 963, 313, 160, 136, 620, 690, 945, 649, 718, 207, 457, 125, 311, 911, 799, 629, 404, 510, 650, 793),
(1056, 599, 411, 843, 311, 752, 560, 797, 304, 805, 289, 476, 535, 315, 336, 805, 487, 820, 125, 589, 269, 415, 409, 329, 245, 316, 737, 561, 176),
(8977, 841, 583, 833, 372, 374, 776, 152, 676, 854, 404, 517, 571, 694, 315, 315, 116, 163, 948, 598, 681, 226, 691, 684, 372, 450, 772, 646, 581)

If you know that every possible Client value will exist in the Consumption table for example, you can just sum the fields and join the tables:

select 
    con.Client,
    sto.Stock1 + sto.Stock2 + sto.Stock3 + sto.Stock4 + sto.Stock5 + sto.Stock6 + sto.Stock7 + sto.Stock8 + sto.Stock9 + sto.Stock10 + sto.Stock11 + sto.Stock12 + sto.Stock13 + sto.Stock14 + sto.Stock15 + sto.Stock16 + sto.Stock17 + sto.Stock18 + sto.Stock19 + sto.Stock20 + sto.Stock21 + sto.Stock22 + sto.Stock23 + sto.Stock24 + sto.Stock25 + sto.Stock26 + sto.Stock27 + sto.Stock28 as Stock,
    con.Consumption1 + con.Consumption2 + con.Consumption3 + con.Consumption4 + con.Consumption5 + con.Consumption6 + con.Consumption7 + con.Consumption8 + con.Consumption9 + con.Consumption10 + con.Consumption11 + con.Consumption12 + con.Consumption13 + con.Consumption14 + con.Consumption15 + con.Consumption16 + con.Consumption17 + con.Consumption18 + con.Consumption19 + con.Consumption20 + con.Consumption21 + con.Consumption22 + con.Consumption23 + con.Consumption24 + con.Consumption25 + con.Consumption26 + con.Consumption27 + con.Consumption28 as Consumption,
    arr.Arrive1 + arr.Arrive2 + arr.Arrive3 + arr.Arrive4 + arr.Arrive5 + arr.Arrive6 + arr.Arrive7 + arr.Arrive8 + arr.Arrive9 + arr.Arrive10 + arr.Arrive11 + arr.Arrive12 + arr.Arrive13 + arr.Arrive14 + arr.Arrive15 + arr.Arrive16 + arr.Arrive17 + arr.Arrive18 + arr.Arrive19 + arr.Arrive20 + arr.Arrive21 + arr.Arrive22 + arr.Arrive23 + arr.Arrive24 + arr.Arrive25 + arr.Arrive26 + arr.Arrive27 + arr.Arrive28 as Arrive
from #A con
left join #B arr on con.Client = arr.Client
left join #C sto on con.Client = sto.Client

If it's possible that a Client might exist in only one or two of the tables and you can't know which one(s), then you need to distinct list of clients first:

select
    cli.Client,
    sto.Stock1 + sto.Stock2 + sto.Stock3 + sto.Stock4 + sto.Stock5 + sto.Stock6 + sto.Stock7 + sto.Stock8 + sto.Stock9 + sto.Stock10 + sto.Stock11 + sto.Stock12 + sto.Stock13 + sto.Stock14 + sto.Stock15 + sto.Stock16 + sto.Stock17 + sto.Stock18 + sto.Stock19 + sto.Stock20 + sto.Stock21 + sto.Stock22 + sto.Stock23 + sto.Stock24 + sto.Stock25 + sto.Stock26 + sto.Stock27 + sto.Stock28 as Stock,
    con.Consumption1 + con.Consumption2 + con.Consumption3 + con.Consumption4 + con.Consumption5 + con.Consumption6 + con.Consumption7 + con.Consumption8 + con.Consumption9 + con.Consumption10 + con.Consumption11 + con.Consumption12 + con.Consumption13 + con.Consumption14 + con.Consumption15 + con.Consumption16 + con.Consumption17 + con.Consumption18 + con.Consumption19 + con.Consumption20 + con.Consumption21 + con.Consumption22 + con.Consumption23 + con.Consumption24 + con.Consumption25 + con.Consumption26 + con.Consumption27 + con.Consumption28 as Consumption,
    arr.Arrive1 + arr.Arrive2 + arr.Arrive3 + arr.Arrive4 + arr.Arrive5 + arr.Arrive6 + arr.Arrive7 + arr.Arrive8 + arr.Arrive9 + arr.Arrive10 + arr.Arrive11 + arr.Arrive12 + arr.Arrive13 + arr.Arrive14 + arr.Arrive15 + arr.Arrive16 + arr.Arrive17 + arr.Arrive18 + arr.Arrive19 + arr.Arrive20 + arr.Arrive21 + arr.Arrive22 + arr.Arrive23 + arr.Arrive24 + arr.Arrive25 + arr.Arrive26 + arr.Arrive27 + arr.Arrive28 as Arrive
from
(
    select con.Client from #A con
    union
    select arr.Client from #B arr
    union
    select sto.Client from #C sto
) cli
left join #A con on cli.Client = con.Client
left join #B arr on cli.Client = arr.Client
left join #C sto on cli.Client = sto.Client

However, as has been pointed out in the comments, this table design seems pretty bad and should probably be changed, for example:

Or even:

In which case your query becomes much simpler:

select
    Client,
    sum(Stock) as Stock,
    sum(Consumption) as Consumption,
    sum(Arrive) as Arrive
from combined_table
group by Client