Question

我有这些表格：

customer:
    customer_id vat_number
    =========== ==========
              1 ES-0000001
              2 ES-0000002
              3 ES-0000003


invoice:
    invoice_id customer_id vat_number
    ========== =========== ==========
           100           1 NULL
           101           3 NULL
           102           3 NULL
           103           2 NULL
           104           3 NULL
           105           1 NULL

我想使用invoice.vat_number的当前值填充customer.vat_number处的NULL值。是否可以使用单个SQL语句执行此操作？

我到目前为止触发了语法错误：

UPDATE invoice
SET vat_number=cu.vat_number /* Syntax error around here */
FROM invoice iv
INNER JOIN customer cu ON iv.customer_id=cu.customer_id
WHERE invoice.invoice_id=iv.invoice_id;

Answer 1

UPDATE invoice i, customer cu SET i.vat_number=cu.vat_number 
WHERE i.customer_id = cu.customer_id;

你去吧

SET vat_number = cu.vat_number / *这里的语法错误* / 该错误是因为var_number列名称不明确 - MySQL不知道这是i.vat_number还是cu，vat_number。

Answer 2

使用MySQL，ANSI-92 JOIN语法：

UPDATE INVOICE
  JOIN CUSTOMER ON CUSTOMER.customer_id = INVOICE.customer_id
   SET vat_number = CUSTOMER.vat_number  
 WHERE INVOICE.vat_number IS NULL

使用MySQL，ANSI-89 JOIN语法：

UPDATE INVOICE, CUSTOMER 
   SET INVOICE.vat_number = CUSTOMER.vat_number  
 WHERE CUSTOMER.customer_id = INVOICE.customer_id
   AND INVOICE.vat_number IS NULL

more info, see the MySQL UPDATE documentation。这是MySQL特定的UPDATE语句语法，不太可能在其他数据库上受支持。

Answer 3

类似的东西：

UPDATE invoice in
SET vat_number=(SELECT cu.vat_number FROM customer cu 
WHERE in.customer_id=cu.customer_id)
-- not tested

Answer 4

UPDATE iv
SET iv.vat_number=cu.vat_number
FROM invoice iv
INNER JOIN customer cu ON iv.customer_id=cu.customer_id

使用另一个表中的值更新表

4 个答案: