Question

我想选择3个表，代码是777

Table 1 
Employee code    Company Name
001                  a
002                  b


Table 2
Employee code    Voucher NO      Date         Amount
001               123            12-4-14      100
001               456            2-5-14       500
002               789            3 -7 14      300

Table 3
Voucher No     Tax amt     code
123             50         777
789             100        888

输出应为

Company Name    Employee code  Voucher No    Date         Amount    Tax amt     code
a                 001             123           12-4-14      100       50         777
a                 001             456           2-5-14       500       null       null

但应用查询时有重复的行

SELECT DISTINCT
 table1.COMPANY_NAME,
 table2.EMPLOYEE_CODE,
 table2.VOUCHER_NO,
 table2.DATE,
 table2.AMOUNT,
 table3.TAX_AMT, 
 table3.CODE
 FROM table2
 INNER JOIN table1 ON (table2.EMPLOYEE_CODE = table1.EMPLOYEE_CODE)
INNER JOIN table3 ON (table2.VOUCHER_NO = table3.VOUCHER_NO ) 
WHERE table3.CODE = '777'

以上查询的输出

Company Name   Employee code   Voucher No    Date     Amount    Tax amt     code
a                 001           123        12-4-14      100       50         777
a                 001           456        2-5-14       500     **50       777**

我尝试使用DISTINCT但是因为没有用。请帮助我查询问题。

Answer 1

试试这个：

SELECT
    table1.COMPANY_NAME,
    table2.EMPLOYEE_CODE,
    table2.VOUCHER_NO,
    table2.DATE,
    table2.AMOUNT,
    table3.TAX_AMT, 
    table3.CODE
FROM table1
    INNER JOIN table2 ON (table2.EMPLOYEE_CODE = table1.EMPLOYEE_CODE)
    LEFT JOIN table3 ON (table2.VOUCHER_NO = table3.VOUCHER_NO ) 
HAVING
    (table3.CODE = '777' OR table3.CODE IS NULL)

如果您需要其他内容，或者您有特定问题，请给我留言。

Answer 2

由于您使用WHERE语句进行过滤，因此SQL命令不会生成您的示例输出。

如果只需要输出777代码，则应使用条件而不是WHERE的LEFT JOIN

 ..... 
 FROM table2
 INNER JOIN table1 ON (table2.EMPLOYEE_CODE = table1.EMPLOYEE_CODE)
 LEFT JOIN table3 ON (table2.VOUCHER_NO = table3.VOUCHER_NO ) 
                     AND (table3.CODE = '777')

Answer 3

您的输出中的第二行可能是因为它在table2中具有相同的EMPLOYEE_CODE，所以我认为这可能是您想要的查询：

SELECT
 table1.COMPANY_NAME,
 table2.EMPLOYEE_CODE,
 table2.VOUCHER_NO,
 table2.DATE,
 table2.AMOUNT,
 table3.TAX_AMT, 
 table3.CODE
 FROM table2
 INNER JOIN table1 ON (table2.EMPLOYEE_CODE = table1.EMPLOYEE_CODE)
LEFT JOIN table3 ON (table2.VOUCHER_NO = table3.VOUCHER_NO ) 
WHERE table1.EMPLOYEE_CODE IN
(SELECT table2.EMPLOYEE_CODE 
FROM table2 INNER JOIN table3 ON (table2.VOUCHER_NO = table3.VOUCHER_NO)
WHERE table3.code = '777')

连接多个表而不重复行

3 个答案: