您可以使用正则表达式：

SELECT REGEXP_REPLACE(
         error,
         '^.*(".*?"\.".*?")\.(".*?")\s+\(\s+actual:\s+(\d+).*$',
         'ALTER TABLE \1 MODIFY \2 VARCHAR2(\3)'
       ) AS query
FROM   table_name

其中，对于示例数据：

CREATE TABLE table_name (error) AS
SELECT 'ORA-12899:value too large for column "SCOTT"."TABLE_EMPLOYEE"."NAME" ( actual: 15, maximum: 10 )' FROM DUAL UNION ALL
-- Handle quoted identifiers with numbers
SELECT 'ORA-12899:value too large for column "test1"."actual 20"."VALUE20" ( actual: 25, maximum: 7 )' FROM DUAL;

输出：
| 查询|
| - -|
| 修改“名称”VARCHAR 2（15）|
| 更改表格“测试1”。“实际值20”修改“值20”变量字符2（25）|
fiddle

您需要编写如下PL/SQL块：

cl scr
set SERVEROUTPUT ON

declare
err varchar2(3000);
cmnd varchar2(3000);
scma varchar2(100);
tbl varchar2(500);
clm varchar2(200);
N varchar2(100);

begin

err:='ORA-12899:value too large for column "SCOTT"."TABLE_EMPLOYEE"."NAME" ( actual 15, maximum:10 )';

select regexp_substr(err, '\w+', 1, 8) into scma from dual; -- Extract 8th word
select regexp_substr(err, '\w+', 1, 9) into tbl from dual;  -- Extract 9th word
select regexp_substr(err, '\w+', 1, 10) into clm from dual;  -- Extract 10th word
select regexp_substr(err, '\w+', 1, 12) into N from dual; -- Extract 12th word

cmnd:='ALTER TABLE "'||scma||'"."'||tbl||'" modify "'||clm||'" varchar2('||N||');';
dbms_output.put_line(cmnd);

end;

结果是：

ALTER TABLE "SCOTT"."TABLE_EMPLOYEE" modify "NAME" varchar2(15);

实际上，您应该生成一个动态SQL，就像您看到的那样。通过这个，您可以从错误中提取的信息生成任何命令。

这里有一个选项，它只使用substr + instr组合。
截至您的示例数据：这很可能是伪造的。“真实的”错误消息如下所示：

SQL> create table table_employee (name varchar2(10));

Table created.

SQL> insert into table_employee (name) values ('Littlefoot Wiki');
insert into table_employee (name) values ('Littlefoot Wiki')
                                          *
ERROR at line 1:
ORA-12899: value too large for column "SCOTT"."TABLE_EMPLOYEE"."NAME" (actual: 15, maximum: 10)

SQL>

在处理这样的字符串时，你只需要精确，否则你会得到意想不到的（错误的）结果。

You   : ORA-12899:value too large for column "SCOTT"."TABLE_EMPLOYEE"."NAME" ( actual 15, maximum:10 )
Really: ORA-12899: value too large for column "SCOTT"."TABLE_EMPLOYEE"."NAME" (actual: 15, maximum: 10)

还有一个例子（对于@MT0 's-正确-反对我之前的代码），表和列包含数字：

SQL> create table test15 (col12umn varchar2(2));

Table created.

SQL> insert into test15 values ('abc');
insert into test15 values ('abc')
                           *
ERROR at line 1:
ORA-12899: value too large for column "SCOTT"."TEST15"."COL12UMN" (actual: 3, maximum: 2)

SQL>

因此：

SQL> with test (col) as
  2    (select 'ORA-12899: value too large for column "SCOTT"."TEST15"."COL12UMN" (actual: 3, maximum: 2)'       from dual union all
  3     select 'ORA-12899: value too large for column "SCOTT"."TABLE_EMPLOYEE"."NAME" (actual: 15, maximum: 10)' from dual
  4    )
  5  select
  6    'alter table ' ||
  7    substr(col, instr(col, '"', 1, 1),
  8                instr(col, '"', 1, 4) - instr(col, '"', 1, 1) + 1
  9          ) ||
 10    ' modify ' ||
 11    substr(col, instr(col, '"', 1, 5),
 12                instr(col, '"', 1, 6) - instr(col, '"', 1, 5) + 1
 13          ) ||
 14    ' varchar2(' ||
 15    substr(col, instr(col, ': ', -1, 2) + 2,
 16                instr(col, ',', -1, 1) - instr(col, ': ', -1, 2) - 2
 17          ) || ')' as result
 18  from test;

RESULT
----------------------------------------------------------------------------------------------------
alter table "SCOTT"."TEST15" modify "COL12UMN" varchar2(3)
alter table "SCOTT"."TABLE_EMPLOYEE" modify "NAME" varchar2(15)

SQL>