需求場景：
業務系統環境升級，數據庫表結構有變動，需要將原數據庫中的所有數據導入到新的數據表結構中。
說到這裏，大家腦海中可能一下會冒出很多方案，如：
1、使用exp和imp
2、使用dblink
針對第一種方案是行不通的，因爲imp導入，必須保證用戶下面是乾淨的，沒有任何與dmp中重複的對象，不然就會導致數據無法正確導入。
針對第二種方案，dblink一般使用場景是在兩臺及以上服務器之間進行數據遷移，dblink它只爲在兩個服務器之間建立一個可互相訪問的橋樑，最終還是需要進行insert into table select * from table。
以下是我自己實現的方案
思路：創建一個臨時用戶，刷入最新表結構，此時表中無任何數據，通過查詢all_tables視圖，查詢出老用戶的所有表對象，並通過查詢dba_tab_columns視圖，查詢出每一個表的數據列，因爲新表相對舊錶有新增字段(注：這些新增字段是允許爲null的，不然這種方案不一定好例)，再通過insert into table(columns) select columns from table語句將數據批量插入到新表中；同時爲防止後續數據插入引起主鍵衝突，還需修改每個表對應序列的開始值，通過查詢dba_sequences視圖，將老用戶中的所有序列對象名和last_number查詢出來，再在新用戶中通過刪除老序列，創建新序列改變它的start with值即可。
步驟如下：
創建一個臨時用戶，刷入最新的表結構，並通過超管賦予如下權限，因爲這些權限在做數據遷移時會用到
grant select on all_tables to TEMP_SDU;
grant select on dba_tab_columns to TEMP_SDU;
grant select on dba_sequences to TEMP_SDU;
grant connect,dba,resource to TEMP_SDU;
grant alter any sequence to TEMP_SDU;
grant create any sequence to TEMP_SDU;
grant execute any procedure to TEMP_SDU;
grant select any table to TEMP_SDU;
創建如下三個存儲過程：
--獲取表中的數據列，並進行批量插入
--table_name 表名
--temp_user 臨時用戶名
create or replace procedure p_getcolumns(table_name varchar2,temp_user varchar2)
as
type ref_table_cursor is ref cursor;
table_cursor ref_table_cursor;
column_name varchar2(200);
str_table_name varchar2(200);
print_column varchar2(10000);
str_sql varchar2(10000);
begin
str_table_name := table_name;
--Check out all the temporary user table column
open table_cursor for select t.COLUMN_NAME from dba_tab_columns t where t.TABLE_NAME=str_table_name and t.OWNER=temp_user;
loop
fetch table_cursor into column_name;
exit when table_cursor%notfound;
--dbms_output.put_line(str_table_name||'--'||column_name);
print_column := print_column||column_name||',';
end loop;
close table_cursor;
print_column := substr(print_column,1,length(print_column)-1);
str_sql := 'insert into '||table_name||'('||print_column||') select '||print_column||' from '||temp_user||'.'||table_name;
--dbms_output.put_line(str_table_name||'--'||str_sql);
execute immediate str_sql;
commit;
print_column := '';
str_sql := '';
end p_getcolumns;
/
--修改序列開始值
--temp_user 臨時用戶名
create or replace procedure p_modify_sequences(temp_user varchar2)
as
cursor cur_sequence is select sequence_name from dba_sequences where sequence_owner=temp_user and sequence_name not like '%S_BME%';
seq_name varchar2(50);
sequence_num number;
num_count number;
begin
open cur_sequence;
loop
fetch cur_sequence into seq_name;
exit when cur_sequence%notfound;
select count(*) into num_count from dba_sequences s where s.sequence_owner=temp_user and s.sequence_name=seq_name;
if num_count>0 then
select s.last_number into sequence_num from dba_sequences s where s.sequence_owner=temp_user and s.sequence_name=seq_name;
select count(*) into num_count from dba_sequences s where s.sequence_owner='TEMP_SDU' and s.sequence_name=seq_name;
if num_count>0 then
execute immediate 'drop sequence '||seq_name;
end if;
execute immediate 'create sequence '||seq_name||' minvalue 1 maxvalue 999999999999 start with '||sequence_num||' increment by 1 nocache cycle';
end if;
end loop;
close cur_sequence;
exception
when no_data_found then
sequence_num:=1;
dbms_output.put_line(sqlerrm);
when others then
sequence_num:=1;
dbms_output.put_line(sqlerrm);
end p_modify_sequences;
/
--數據遷移調用的入口存儲過程
create or replace procedure p_datamove(temp_user varchar2)
as
type ref_table_cursor is ref cursor;
table_cursor ref_table_cursor;
column_name varchar2(200);
--All the tables in the query in temporary user
cursor cur is select t.table_name from all_tables t where t.owner=temp_user and t.table_name not in('ECONF_ADMIN_INFO','ECONF_OPERATOR_PSWD_INFO','ECONF_EMAILSERVER','ECONF_HIREPORTS_INFO','ECONF_CONFIG','ECONF_EMAIL_FORMAT','ECONF_MS_FILE','ECONF_SVC_FEATURE_DATA','ECONF_IVR_VOICE_FILE','ECONF_IVR_VOICE_FILE_MCU','ECONF_SVC_DATA');
str_sql varchar2(200);
table_name varchar2(200);
isexist number;
begin
--savepoint p1;
--Traverse each table name in the cursor
open cur;
loop
fetch cur into table_name;
exit when cur%NOTFOUND;
select instr(table_name,'ECONF_') into isexist from dual;
if isexist>0 then
--Get all the columns in the table, and the migration of data in each table
p_getcolumns(table_name,temp_user);
end if;
end loop;
close cur;
--modify sequences value
p_modify_sequences(temp_user);
exception
when others then
dbms_output.put_line(sqlerrm);
--rollback to savepoint p1;
end p_datamove;
/