[20210723]Database link and user defined datatypes.txt

[20210723]Database link and user defined datatypes.txt --//如何通过db link访问用户定义类型.按照链接做测试. https://laurentschneider.com/wordpress/2021/07/database-link-and-user-defined-datatypes.html 1.环境: SCOTT@book> @ ver1 PORT_STRING                    VERSION        BANNER ------------------------------ -------------- -------------------------------------------------------------------------------- x86_64/Linux 2.4.xx            11.2.0.4.0     Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production 2.测试: create type tt as object (x number); / create table t (x tt); insert into t values (tt(1)); commit; SCOTT@book> select t.x.x from t t;        X.X ----------          1 --//OK,本地访问没有问题. CREATE PUBLIC DATABASE LINK LOOPBACK USING 'localhost:1521/book'; SCOTT@book> select t.x.x from t@LOOPBACK t;        X.X ----------          1 --//采用本地loopback测试不出来. 3.继续: CREATE PUBLIC DATABASE LINK L78  CONNECT TO SCOTT  IDENTIFIED BY <Password>  USING '192.168.100.78:1521/book'; SCOTT@test> select sysdate from dual@l78; SYSDATE ------------------- 2021-07-23 09:47:24 --//OK. SCOTT@test> select t.x.x from t@L78 t; select t.x.x from t@L78 t        * ERROR at line 1: ORA-22804: remote operations not permitted on object tables or user-defined type columns SCOTT@test> select type_name,TYPE_OID from user_types@L78; TYPE_NAME                      TYPE_OID ------------------------------ -------------------------------- TT                             C7C175F2E6ED5C33E0534E64A8C010B5 SCOTT@test> create type tt oid 'C7C175F2E6ED5C33E0534E64A8C010B5' as object(x number)   2  / Type created. --//视乎建立的type不指定可以唯一. SCOTT@test> select t.x.x from t@L78 t;        X.X ----------          1 --//感觉type的东西很少用,做一个记录.