IF OBJECT_ID(N'[奶粉销售表]') IS NOT NULL DROP TABLE [奶粉销售表]
IF OBJECT_ID(N'[玩具销售表]') IS NOT NULL DROP TABLE [玩具销售表]
IF OBJECT_ID(N'[客户表]') IS NOT NULL DROP TABLE [客户表]
GO
CREATE TABLE [奶粉销售表]([客户表ID] varchar(20),[客户姓名] varchar(20),[销售金额] int)
CREATE TABLE [玩具销售表]([客户表ID] varchar(20),[客户姓名] varchar(20),[销售金额] int)
CREATE TABLE [客户表]([客户表ID] varchar(20),[客户姓名] varchar(20),[联系电话] int)
GO
insert into [奶粉销售表]
select 'A001','张三',210 union all
select 'A002','李四',135 union all
select 'A001','张三',140

insert into [玩具销售表]
select 'A002','李四',120 union all
select 'A003','王五',380 union all
select 'A001','张三',110 union all
select 'A003','王五',30 

insert into [客户表]
select 'A001','张三',111 union all
select 'A002','李四',222 union all
select 'A003','王五',333 union all
select 'A004','赵六',444


SELECT a.[客户表ID],a.[客户姓名],ISNULL(b.[奶粉销售金额],0) AS '奶粉销售金额',ISNULL([玩具销售金额],0)AS '玩具销售金额',a.[联系电话] FROM [客户表] a
LEFT JOIN (SELECT [客户表ID],SUM([销售金额]) AS '奶粉销售金额' FROM [奶粉销售表] GROUP BY [客户表ID]) b
ON a.[客户表ID]=b.[客户表ID]
LEFT JOIN (SELECT [客户表ID],SUM([销售金额]) AS '玩具销售金额' FROM [玩具销售表] GROUP BY [客户表ID]) c
ON a.[客户表ID]=c.[客户表ID]

/*
(3 行受影响)

(4 行受影响)

(4 行受影响)
客户表ID                客户姓名                 奶粉销售金额      玩具销售金额      联系电话
-------------------- -------------------- ----------- ----------- -----------
A001                 张三                   350         110         111
A002                 李四                   135         120         222
A003                 王五                   0           410         333
A004                 赵六                   0           0           444

(4 行受影响)

*/

------解决方案--------------------
SQL code

--借用下关将军的数据
IF OBJECT_ID(N'[奶粉销售表]') IS NOT NULL DROP TABLE [奶粉销售表]
IF OBJECT_ID(N'[玩具销售表]') IS NOT NULL DROP TABLE [玩具销售表]
IF OBJECT_ID(N'[客户表]') IS NOT NULL DROP TABLE [客户表]
GO
CREATE TABLE [奶粉销售表]([客户表ID] varchar(20),[客户姓名] varchar(20),[销售金额] int)
CREATE TABLE [玩具销售表]([客户表ID] varchar(20),[客户姓名] varchar(20),[销售金额] int)
CREATE TABLE [客户表]([客户表ID] varchar(20),[客户姓名] varchar(20),[联系电话] int)
GO
insert into [奶粉销售表]
select 'A001','张三',210 union all
select 'A002','李四',135 union all
select 'A001','张三',140

insert into [玩具销售表]
select 'A002','李四',120 union all
select 'A003','王五',380 union all
select 'A001','张三',110 union all
select 'A003','王五',30 

insert into [客户表]
select 'A001','张三',111 union all
select 'A002','李四',222 union all
select 'A003','王五',333 union all
select 'A004','赵六',444


SELECT 
        a.[客户表ID],
        a.[客户姓名],
        ISNULL(b.[奶粉销售金额],0) AS '奶粉销售金额',
        ISNULL([玩具销售金额],0)AS '玩具销售金额',
        ISNULL(a.[联系电话],0) FROM [客户表] a
LEFT JOIN 
            (SELECT 
                   [客户表ID],
                   SUM([销售金额]) AS '奶粉销售金额' 
               FROM [奶粉销售表] GROUP BY [客户表ID]) b
ON a.[客户表ID]=b.[客户表ID]
LEFT JOIN
            (SELECT 
                   [客户表ID],
                   SUM([销售金额]) AS '玩具销售金额' 
               FROM [玩具销售表] GROUP BY [客户表ID]) c
ON a.[客户表ID]=c.[客户表ID]