在 Oracle 触发器中将新行转换为 XML
Posted
技术标签:
【中文标题】在 Oracle 触发器中将新行转换为 XML【英文标题】：Convert the new row to XML inside a Oracle Trigger 【发布时间】：2020-11-01 14:58:27 【问题描述】：您好，我正在尝试使用 oracle 触发器在表中创建更改日志
日志表由 ,time of action ,tablename,actiontype 和 xmldata (clob) 组成
我正在尝试将新行转换为 xml 并将其保存为 xmldata
create or replace TRIGGER EVAL_CHANGE_TriggerActual_DYNAMIC
AFTER INSERT OR UPDATE OR DELETE
ON PROJ_TEST
REFERENCING NEW AS new OLD AS old
FOR EACH ROW
DECLARE
log_action varchar(10);
p_xmldata XMLtype;
P_NEWROWDATA clob;
p_newrowxml clob;
BEGIN
select rtrim(xmlelementcol,',') into p_newrowxml from ( Select LISTAGG(str, '') as xmlelementcol from (select 'XMLElement("'||cols.column_Name||'", :NEW.'||cols.column_name||'),' as str
from SYS.ALL_TAB_COLS cols where upper(cols.owner)=upper('DEV_CUSTOM') and upper(cols.table_name)=upper('PROJ_TEST') order by column_id ));
p_newrowxml:=CONCAT('select XMLElement("ResearchTable",',p_newrowxml);
p_newrowxml:=CONCAT(p_newrowxml,')from dual');
DBMS_OUTPUT.PUT_LINE(p_newrowxml);
EXECUTE IMMEDIATE p_newrowxml into p_xmldata;
p_newrowdata:=p_xmldata.getClobVal();
IF INSERTING THEN
log_action := 'Insert';
ELSIF UPDATING THEN
log_action := 'Update';
ELSIF DELETING THEN
log_action := 'Delete';
ELSE
DBMS_OUTPUT.PUT_LINE('This code is not reachable.');
END IF;
INSERT INTO audits(table_name, transaction_name, by_user, transaction_date,xmldata,TRIGGERNAMEdesc)
VALUES('PROJ_TEST', log_action, USER, SYSDATE,p_newrowdata,'EVAL_CHANGE_TriggerDynamic');
END;
现在如果我删除下面的代码
'XMLElement("'||cols.column_Name||'", :NEW.'||cols.column_name||'),'
到
'XMLElement("'||cols.column_Name||'", 1),'
否则它的工作不会在立即执行时出现错误。谁能帮忙
【问题讨论】：
【参考方案1】：触发器中的一个陷阱是： :new / :old 是非常特定于触发器的并且处理起来很乏味。一种解决方法是显式构造 xmltype：
create or replace TRIGGER EVAL_CHANGE_TRIGGER
AFTER INSERT OR UPDATE OR DELETE
REFERENCING NEW AS NEW OLD AS OLD
ON ResearchTable
DECLARE
log_action varchar(10);
p_xmldata XMLtype;
p_newrowdata clob;
BEGIN
select XMLElement("ResearchTable",
XMLElement("myColumn1", :NEW.myColumn1),
XMLElement("myColumn2", :NEW.myColumn2),
....)
into p_xmldata from dual;
p_newrowdata:=p_xmldata.getClobVal();
IF INSERTING THEN
log_action := 'Insert';
ELSIF UPDATING THEN
log_action := 'Update';
ELSIF DELETING THEN
log_action := 'Delete';
ELSE
DBMS_OUTPUT.PUT_LINE('This code is not reachable.');
END IF;
INSERT INTO auditsResearch (table_name, transaction_name, by_user, transaction_date,XMLDATA)
VALUES('PROJ_TEST', log_action, USER, SYSDATE,p_newrowdata);
END;
xml-generation 是非常特定于表的（因为 :new - 限制），我会通过查询目标表的元数据来使用一些代码生成：
select 'XMLElement("'||cols.column_Name||'", :NEW.'||cols.column_name||'),'
from SYS.ALL_TAB_COLS cols
where upper(cols.owner)=upper('MY_TARGET_SCHEMA')
and upper(cols.table_name)=upper('MY_TABLE')
order by column_id
;
【讨论】：
嗨，Michael 先生 ..您的想法似乎可行 ..但我在创建代码生成时遇到错误，我更新了问题中的代码。请您帮帮我 最后一个 sql 仅用于源代码生成，不用于触发器。执行触发器外部的sql，用生成的数据修改触发器。 代码生成仅在您必须“审核”许多表时才有用......如果您的触发器仅用于一个具有几列的表，则此技术是过度的 您可以创建一个包，通过遍历所有表来生成触发器代码，为每个表创建触发器代码并“立即执行”以创建真正的触发器。 “删除”操作可能需要特别注意，所有 :new.XX 都应该为空，只有 :old 可用【参考方案2】：虽然我的第一个答案有效，但它在很大程度上取决于表格列，如果必须审核许多表格，则不会真正使用。基于@Sayan Malakshinov 的评论和链接的文章StevenFeuerstein&CompoundTrigger。如果在一次更新中处理了许多行，最终的审计循环可能会导致性能问题....批量更新可以移动到更优化的更新复合触发器，将所有更新行写入一个“插入到 tblaudit( ) select auditColumns from tblone where id in (recorded id´s)"
-- prepare test-scenario
CREATE TABLE TBLONE
(
ID NUMBER(19),
POSTALCODE VARCHAR2(20 CHAR),
STREET VARCHAR2(255 CHAR),
HOUSENUMBER VARCHAR2(25 CHAR),
CITY VARCHAR2(255 CHAR)
)
;
ALTER TABLE TBLONE ADD (
PRIMARY KEY
(ID)
USING INDEX);
insert into tblone values (1,'123123','street1','1a','DevVille1');
insert into tblone values (2,'345','street2','2b','DevVille2');
insert into tblone values (3,'678','street3','3c','DevVille3');
CREATE TABLE TBLAUDIT
(
ID NUMBER(19),
log_action VARCHAR2(10 CHAR),
log_user varchar(100 char),
log_data clob
)
;
-- ... timestamp of modification might be missing ...
CREATE OR REPLACE TRIGGER trg_audit_tblone
FOR UPDATE OR INSERT OR DELETE ON tblone
COMPOUND TRIGGER
TYPE id_rt IS RECORD (
id_column NUMBER(19) -- assuming all primary-keys are of same type ....
,log_action varchar(10)
);
TYPE row_level_info_t IS TABLE OF id_rt INDEX BY PLS_INTEGER;
g_row_level_info row_level_info_t;
AFTER EACH ROW IS
BEGIN
g_row_level_info (g_row_level_info.COUNT + 1).id_column := :NEW.id; -- store primary key only
-- remember the type of trigger-action
IF INSERTING THEN
g_row_level_info (g_row_level_info.COUNT).log_action := 'Insert';
ELSIF UPDATING THEN
g_row_level_info (g_row_level_info.COUNT).log_action := 'Update';
ELSIF DELETING THEN
g_row_level_info (g_row_level_info.COUNT).log_action := 'Delete';
end if;
END AFTER EACH ROW;
AFTER STATEMENT IS
l_rowdata clob;
BEGIN
-- for all row-actions recorded
FOR indx IN 1 .. g_row_level_info.COUNT
LOOP
if g_row_level_info (indx).log_action= 'Delete' then
-- no row selectable, direct insert to audit
insert into TBLAUDIT values(g_row_level_info(indx).id_column,sys_context('USERENV','SESSION_USER') , g_row_level_info (indx).log_action,null);
else
select xmltype(cursor(select * from tblone where id=g_row_level_info (indx).id_column)).getclobval() into l_rowdata from dual;
insert into TBLAUDIT values(g_row_level_info(indx).id_column,sys_context('USERENV','SESSION_USER') , g_row_level_info (indx).log_action,l_rowdata);
end if;
END LOOP;
END AFTER STATEMENT;
END trg_audit_tblone;
update tblone
set street='newStreet'
where id=1;
select id,log_action,log_user,dbms_lob.substr(log_data,200) from tblaudit;
update tblone
set street='newStreet';
select id,log_action,log_user,dbms_lob.substr(log_data,200) from tblaudit;
delete from tblone where id=2;
select id,log_action,log_user,dbms_lob.substr(log_data,200) from tblaudit;
如果真的需要考虑多行更新：
create TYPE type_audit_entry as object (
id_column NUMBER(19) -- assuming all primary-keys are of same type ....
,log_action varchar(10)
);
create type typeTable_audit as table of type_audit_entry;
CREATE OR REPLACE TRIGGER trg_audit_update_tblone
FOR UPDATE ON tblone
COMPOUND TRIGGER
g_row_level_info typeTable_audit := typeTable_audit();
BEFORE STATEMENT IS
BEGIN
g_row_level_info:=typeTable_audit();
END BEFORE STATEMENT;
AFTER EACH ROW IS
BEGIN
g_row_level_info.extend;
g_row_level_info (g_row_level_info.COUNT):=type_audit_entry(:NEW.id,null);
END AFTER EACH ROW;
AFTER STATEMENT IS
l_rowdata clob;
BEGIN
insert into TBLAUDIT(ID,log_action,log_user,log_time,log_data)
select stored_audit.id_column,'Update',sys_context('USERENV','SESSION_USER'),sysdate,xmltype(cursor(select * from tblone where id=stored_audit.id_column)).getclobval()
from TABLE(g_row_level_info) stored_audit;
END AFTER STATEMENT;
END trg_audit_update_tblone;
delete from tblaudit;
update tblone
set street='newStreet';
select id,log_action,log_time,log_user,dbms_lob.substr(log_data,200) from tblaudit;
【讨论】：
很好，但组合主键会失败 ?它必须用于组合键，仅此而已。该方法本身并不关心关键结构 或直接从 oracle 使用商业审计选项，不涉及编码 您好，我使用了您的建议并缩小了错误范围，请您检查更新后的问题，它似乎是一些语法问题 正如我在 cmets 中对我的回答所说，您可以更好地改进您的解决方案：只需将所有更改的行聚合到一个 xmltype 中：select xmltype(cursor(select * from tblone t,table(your_collection) nt where t.id=nt.column_value)) xml_agg_rows from dual【参考方案3】：
有一种简单的方法可以将整行甚至记录集转换为 xml：您可以将 cursor 包装起来并将其作为输入参数传递给 XMLType。例如：
select xmltype(cursor(select * from test where N=1)) from dual;
PL/SQL 示例：
declare x xmltype;
begin
select xmltype(cursor(select * from test where N=1))
into x
from dual;
dbms_output.put_line(x.getclobval());
end;
/
【讨论】：
虽然这在 pl/sql 中可用，但在触发器中不起作用。在触发器中，您将得到一个“ora-04091”，选择触发器所在的同一张表 @MichaelHauptmann 这不是问题：而不是单行级（在行级触发器中运行大量代码非常慢），我会将其更改为复合触发器，其中在行-级别触发器我只是在语句后触发器中聚合 ID 并将更改的行的整个行集聚合到一个 xmltype 中。 所以基本上是oraclemagazine 的方法。即使使用复合触发器，您也无法选择触发表而不会导致 ora-04091 .... 或者您有工作示例吗？ @MichaelHauptmann ora-04091 出现在行级触发器中，而不是语句级：stevenfeuersteinonplsql.blogspot.com/2016/12/…。 @SayanMalakshinov 具有空值的列不会出现在生成的 xml 中以上是关于在 Oracle 触发器中将新行转换为 XML的主要内容，如果未能解决你的问题，请参考以下文章
在oracle中插入表B后创建触发器以将新行添加到表A中时出错