开篇立意

oracle在函数中使用dml语句时，有两者情况。即：（1）直接使用select调用该函数；（2）在匿名块中调用该函数。
针对第一种情况我们测试一下
简单的函数：

create table nested_tab(id int, name varchar2(100), job varchar2(100), age int);
insert into nested_tab values (1, 'asda', 'gfdgd', 12);
insert into nested_tab values (2, 'sdfsd', 'cvxvx', 14);
insert into nested_tab values (3, 'uyiy', 'mmbv', 16);create or replace function support_dml return int as
beginupdate nested_tab set id = 4 where name = 'uyiy';return 12;
end;
/
报错如下
SQL> select support_dml() from dual;
select support_dml() from dual*
ERROR at line 1:
ORA-14551: cannot perform a DML operation inside a query
ORA-06512: at "SYS.SUPPORT_DML", line 3

针对第二种情况我们测试一下

declareretcode int := 1;
beginretcode := support_dml();dbms_output.put_line(retcode);
end;
/
12PL/SQL procedure successfully completed.

由此可以知道定义在函数中的dml，只能在plsql中使用。

plorasql实现

lightdb 在兼容的过程中，上面描述的oracle的两种情况都支持。

plorasql测试

create table nested_tab(id int, name varchar2(100), job varchar2(100), age int);
insert into nested_tab values (1, 'asda', 'gfdgd', 12);
insert into nested_tab values (2, 'sdfsd', 'cvxvx', 14);
insert into nested_tab values (3, 'uyiy', 'mmbv', 16);create or replace function support_dml return int as
beginupdate nested_tab set id = 4 where name = 'uyiy';return 12;
end;
/lightdb@test_hs_oracle=# select support_dml() from dual;support_dml 
-------------12
(1 row)lightdb@test_hs_oracle=# select dbms_output.serveroutput('t');serveroutput 
--------------(1 row)lightdb@test_hs_oracle=# declare
lightdb@test_hs_oracle$# retcode int := 1;
lightdb@test_hs_oracle$# begin
lightdb@test_hs_oracle$#     retcode := support_dml();
lightdb@test_hs_oracle$# dbms_output.put_line(retcode);
lightdb@test_hs_oracle$# end;
lightdb@test_hs_oracle$# /
12
DO