1，修改1列

update student s, city c
set s.city_name = c.name
where s.city_code = c.code;

2，修改多個列

update  a,  b
set a.title=b.title, a.name=b.name
where a.id=b.id

• 子查詢

update student s set city_name = (select name from city where code = s.city_code);

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oracle查詢報這個錯誤：single-row subquery returns more than one row怎麼解決？ 

資料庫按照你的條件查詢有多個重複的資料。

例如：

UPDATE "SYS_ROLE" A

SET A ."DEPT_ID" = (

    SELECT

        c."id"

    FROM

        "his_department_info" c

    WHERE

        c."dept_name" = A ."ROLE_NAME"
 

如果以上sql語句報single-row subquery returns more than one row的錯誤，說明 c表”dept_name” 和A 表.”ROLE_NAME” 的這兩個欄位 資料重複

2、 寫法輕鬆，更新效率高：

update table1 
set field1=table2.field1,
field2=table2.field2
from table2
where table1.id=table2.id