CREATE TABLE #d1
(
    client       int             NULL,
    credit       int             NULL,
    deposit      int             NULL
)
CREATE TABLE #d2
(
    client       int             NULL,
    credit       int             NULL,
    deposit      int             NULL
)

INSERT INTO #d1 VALUES  ( 1 ,  1 , NULL)
INSERT INTO #d1 VALUES  ( 1 ,  2 , NULL)
INSERT INTO #d1 VALUES  ( 1 ,  3 , NULL)

INSERT INTO #d1 VALUES  ( 2 ,  11 , NULL)
INSERT INTO #d1 VALUES  ( 2 ,  12 , NULL)
INSERT INTO #d1 VALUES  ( 2 ,  13 , NULL)

INSERT INTO #d1 VALUES  ( 3 ,  21 , NULL)
INSERT INTO #d1 VALUES  ( 3 ,  22 , NULL)
INSERT INTO #d1 VALUES  ( 3 ,  23 , NULL)
INSERT INTO #d1 VALUES  ( 3 ,  24 , NULL)

INSERT INTO #d2 VALUES  ( 1 , NULL,  200 )
INSERT INTO #d2 VALUES  ( 1 , NULL,  100 )
INSERT INTO #d2 VALUES  ( 1 , NULL,  400 )
INSERT INTO #d2 VALUES  ( 1 , NULL,  300 )

INSERT INTO #d2 VALUES  ( 2 , NULL,  110 )
INSERT INTO #d2 VALUES  ( 2 , NULL,  120 )

/* Нужно получить результат в виде SELECT */
client credit deposit
     1 ,       1 ,     200 
     1 ,       2 ,     100 
     1 ,       3 ,     400 
     1 ,   NULL,     300 
     2 ,      11 ,     110 
     2 ,      12 ,     120 
     2 ,      13 ,   NULL
     3 ,      21 ,   NULL   
     3 ,      22 ,   NULL
     3 ,      23 ,   NULL
     3 ,      24 ,   NULL

DROP TABLE #d1
DROP TABLE #d2

select
d1.client,
coalesce(d1.credit,d2.credit) as credit,
coalesce(d1.deposit,d2.deposit) as deposit
from
#d1
left outer join #d2 on (d2.client=d1.client)

CREATE TABLE #d1
(
    id_1         numeric         identity,
    client       int             NULL,
    credit       int             NULL,
    deposit      int             NULL
)
CREATE TABLE #d2
(
    id_2         numeric         identity,
    client       int             NULL,
    credit       int             NULL,
    deposit      int             NULL
)

CREATE TABLE #d1
(
   id            numeric     identity,
    client       int             NULL,
    credit       int             NULL,
    deposet      int             NULL
)

CREATE TABLE #d2
(
   id            numeric     identity,
   client        int             NULL,
   credit        int             NULL,
   deposet       int             NULL
)

CREATE TABLE #d3
(
    client        int             NULL,
    count_credit  int             NULL,
    count_deposit int             NULL
)

CREATE TABLE #d4
(
    id           numeric     identity,
    client       int             NULL,
    credit       int             NULL,
    deposet      int             NULL,
    id_2         int             NULL
)

DECLARE @id     int
DECLARE @id_max int

/* Исходные данные */
INSERT INTO #d1 VALUES  ( 1 ,  1 , NULL)
INSERT INTO #d1 VALUES  ( 1 ,  2 , NULL)
INSERT INTO #d1 VALUES  ( 1 ,  3 , NULL)

INSERT INTO #d1 VALUES  ( 2 ,  11 , NULL)
INSERT INTO #d1 VALUES  ( 2 ,  12 , NULL)
INSERT INTO #d1 VALUES  ( 2 ,  13 , NULL)

INSERT INTO #d1 VALUES  ( 3 ,  21 , NULL)
INSERT INTO #d1 VALUES  ( 3 ,  22 , NULL)
INSERT INTO #d1 VALUES  ( 3 ,  23 , NULL)
INSERT INTO #d1 VALUES  ( 3 ,  24 , NULL)

INSERT INTO #d2 VALUES  ( 1 , NULL,  200 )
INSERT INTO #d2 VALUES  ( 1 , NULL,  100 )
INSERT INTO #d2 VALUES  ( 1 , NULL,  400 )
INSERT INTO #d2 VALUES  ( 1 , NULL,  300 )

INSERT INTO #d2 VALUES  ( 2 , NULL,  110 )
INSERT INTO #d2 VALUES  ( 2 , NULL,  120 )

/* Получаем список клиентов */
INSERT INTO #d3( client ) SELECT DISTINCT client  FROM #d1
INSERT INTO #d3( client ) SELECT DISTINCT client  FROM #d2 WHERE #d2.client not in (SELECT client FROM #d3)

/* Проставляем кол-во кредитов депозитов */
UPDATE #d3 SET count_credit  = (SELECT count(client) FROM #d1 WHERE  #d1.client = #d3.client)
UPDATE #d3 SET count_deposit = (SELECT count(client) FROM #d2 WHERE  #d2.client = #d3.client)

/* Получаем результирующую табличку */
INSERT INTO 
        #d4 (client, credit) 
SELECT 
        #d1.client,  #d1.credit 
  FROM 
        #d1, #d3 
 WHERE 
        #d3.client          = #d1.client       and 
        #d3.count_credit    >= #d3.count_deposit


INSERT INTO
       #d4 (client, deposet)
SELECT
       #d2.client,  #d2.deposet
  FROM
       #d2, #d3
 WHERE 
       #d3.client           = #d2.client        and 
       #d3.count_credit     < #d3.count_deposit

/* Результирующая таблица */
--SELECT client, credit, deposet FROM #d4 ORDER BY client

/* проставляем флаг не обработанной строки */
UPDATE #d4 SET #d4.id_2 =  0 

/* Начальная и максимальная строка */
select  @id = min(id) from #d4
select  @id_max = max(id) from #d4

/* Цикл для каждой строчкам в результирующей таблицы (лучше не придумал) */
WHILE @id < @id_max
BEGIN
    /* Поиск ID депозита */
    UPDATE
           #d4
       SET
           #d4.id_2 = (
                           SELECT 
                                  Min(#d2.id)
                             FROM 
                                   #d2
                            WHERE 
                                   #d4.client = #d2.client and 
                                   #d2.id >  (SELECT Max(id_2) FROM #d4 WHERE #d4.client = #d2.client)
                          )
    WHERE 
          #d4.deposet = null and #d4.id = @id
  
    /* Проставляем депозит */
    UPDATE
            #d4
       SET
            #d4.deposet = #d2.deposet
      FROM 
            #d2
     WHERE 
            #d4.id_2    = #d2.id and 
            #d4.id      = @id

    /* Поиск кредита */
    UPDATE
           #d4
       SET
           #d4.id_2 = (
                           SELECT 
                                   Min(#d1.id)
                             FROM 
                                   #d1
                            WHERE 
                                   #d4.client = #d1.client and 
                                   #d1.id >  (SELECT Max(id_2) FROM #d4 WHERE #d4.client = #d1.client)
                          )
    WHERE 
           #d4.credit   = null and 
           #d4.id       = @id

    /* Проставляем креди */
    UPDATE
           #d4
       SET
           #d4.credit = #d1.credit
      FROM 
           #d1
     WHERE 
           #d4.id_2 = #d1.id and #d4.id = @id

    /* Номер следующей строки */
    SELECT @id = @id +  1 
    
END

/* Столь нужный результат */
SELECT client, credit, deposet  FROM #d4 ORDER BY client

DROP TABLE #d1
DROP TABLE #d2
DROP TABLE #d3
DROP TABLE #d4