Question

如何将一百万个记录从一个表复制到另一个表。如果在复制记录时发生任何错误，我需要将记录（错误记录）复制到其他表中。

Answer 1

使用LOG ERRORS功能。它将行级故障信息写出到先前定义的错误日志表中-并继续进行。这是一个LiveSQL script，带您逐步进行操作。我也在下面提供它们。假定您具有对employees表的访问权限，可以从here安装该表。

关于日志错误，要记住的一件非常重要的事情是，只要遇到的错误数小于限制（或限制为“无限”），在语句完成后就不会引发错误。

希望这会有所帮助！

BEGIN  
   DBMS_ERRLOG.create_error_log (dml_table_name => 'EMPLOYEES');  
END; 
/

-- Show Columns of Error Log Table
-- DBMS_ERRLOG creates a table that starts with five error-related columns: ORA_ERR_NUMBER$ (error code), ORA_ERR_MESG$ (error message), ORA_ERR_ROWID$, ORA_ERR_OPTYP$ (operation type - U, I, D), ORA_ERR_TAG$ (optional "tag" text you can provide in LOG ERRORS clause). Then it adds VARCHAR2(4000) columns for any column in DML table that is compatible with VARCHAR2. Example: DATE works, but CLOB does not.
SELECT column_name, data_type 
  FROM user_tab_columns 
 WHERE table_name = 'ERR$_EMPLOYEES' 
ORDER BY COLUMN_ID;

-- All or Nothing - Without LOG ERRORS
-- This step shows you how the results of a DML statement are usually "all or nothing" - either all rows specified by the DML statement are changed successfully, or none are. That is, if N rows are modified, but then the N+1 row causes an error, the changes to the previous N rows are rolled back. So the number of people making a salary > 24000 is 0, both before and after the UPDATE, since at least one person's salary, when multiplied by 200, exceeds the constraint on the salary column.
DECLARE  
   l_count   PLS_INTEGER;  
BEGIN  
   SELECT COUNT ( * )  
     INTO l_count  
     FROM employees  
    WHERE salary > 24000;  

   DBMS_OUTPUT.put_line ('Before ' || l_count);  

   UPDATE employees  
      SET salary = salary * 200;  

   SELECT COUNT ( * )  
     INTO l_count  
     FROM employees  
    WHERE salary > 24000;  
EXCEPTION  
   WHEN OTHERS  
   THEN  
      DBMS_OUTPUT.put_line (DBMS_UTILITY.format_error_stack);  

      SELECT COUNT ( * )  
        INTO l_count  
        FROM employees  
       WHERE salary > 24000;  

      DBMS_OUTPUT.put_line ('After ' || l_count);  
END; 
/

-- Suppressing Row-Level Errors
-- Now I run the script again, with LOG ERRORS added, also specifying that I don't care how many errors occur - just keeping going. The net result is that of the 107 rows in the employees table, 49 are updated, while 58 have errors. Nice!
DECLARE  
   l_count   PLS_INTEGER;  
BEGIN  
   SELECT COUNT ( * )  
     INTO l_count  
     FROM employees  
    WHERE salary > 24000;  

   DBMS_OUTPUT.put_line ('Before ' || l_count);  

       UPDATE employees  
          SET salary = salary * 200  
LOG ERRORS  INTO ERR$_EMPLOYEES (substr (last_name, 1, 20)) REJECT LIMIT UNLIMITED;   

   DBMS_OUTPUT.put_line ('After - SQL%ROWCOUNT ' || SQL%ROWCOUNT);   

   SELECT COUNT ( * )   
     INTO l_count   
     FROM employees   
    WHERE salary > 24000;   

   DBMS_OUTPUT.put_line ('After - Count in Table ' || l_count);  

   ROLLBACK;  
END; 
/

SELECT COUNT ( * ) "Number of Failures" 
  FROM err$_employees ;

-- Check the Error Log Table!
-- When you use LOG ERRORS, it is absolutely critical that you check the table immediately after the DML statement for errors from that statement. The SQL statement does not terminate with an exception, so looking at the table is THE ONLY WAY to know if anything went wrong! A common action at this point is to move the error information from your table-specific DML error log table to a persistent application error log table.
SELECT ora_err_mesg$, ora_err_rowid$, ora_err_tag$, last_name  
  FROM err$_employees  
 WHERE ROWNUM < 10 ;

-- Clean Up the Error Log Table
-- After checking the contents, I clean out the table, so the contents do not confuse me when I execute the next DML statement on the table.
BEGIN  
   DELETE FROM err$_employees;  

   COMMIT;  
END; 
/

-- Specify Limit on Rejections (Errors)
-- Suppose I am doing a bulk update, but I expect that very few errors will occur. If more than 10 row updates fail, something is wrong, and I want to simply stop. Then LOG ERRORS REJECT LIMIT 10 will do the trick.
BEGIN  
       UPDATE employees  
          SET first_name = first_name || first_name || first_name  
   LOG ERRORS REJECT LIMIT 10;  

   ROLLBACK;  
END; 
/

SELECT 'Number of errors = ' || COUNT ( * ) 
  FROM err$_employees ;

将数百万条记录从一张表复制到另一张表

1 个答案: