oracle数据库修改表字段类型

1、表字段由 NUMBER 改为 VARCHAR2

1、新建表字段
ALTER TABLE "CREDIT_ENTER_RECORD" ADD ("NEW_ID" VARCHAR2(100));

2、将旧字段值赋值给新字段
UPDATE "CREDIT_ENTER_RECORD" SET "NEW_ID" = "ID";

3、删除旧字段
ALTER TABLE "CREDIT_ENTER_RECORD" DROP COLUMN "ID";

4、新字段改名为旧字段
ALTER TABLE "CREDIT_ENTER_RECORD" RENAME COLUMN "NEW_ID" TO "ID";

2、另外一个表中某列数据赋值到本表某一列中

UPDATE MANAGEMENT_SYSTEM t2
SET t2.FILE_LIST = (
    SELECT t1.FILE_LIST
    FROM MANAGEMENT t1
    WHERE t1.SUBMIT_NUM = t2.SUBMIT_NUM
)
WHERE EXISTS (
    SELECT 1
    FROM MANAGEMENT t1
    WHERE t1.SUBMIT_NUM = t2.SUBMIT_NUM
);