如题:
1.16进制数在转化成10进制数时出错SQL> select to_char(125,'xxxx') from dual;
TO_CHAR(125,'XXXX')
--------------------------------------------------------------------------------
7d
SQL> select to_char(7d,'xxx') from dual;
TO_CHAR(7.0E+000D,'XXX')
--------------------------------------------------------------------------------
7SQL> select to_char(to_char(125,'xxxx'),'xxx') from dual;
select to_char(to_char(125,'xxxx'),'xxx') from dual
ORA-01722: 无效数字2.索引高度是什么一个概念: pga_aggregate_target?
3.analyze index indexname validate structure有什么用?--判断是否需要重建索引?
4.以下代码怎样才能输出“Test successed!”SQL> set serveroutput on;
SQL> create or replace and compile java source named test_java as
2 public class FirstJava{
3 public static void test(){
4 System.out.println("Test successed!");
5 }
6 };
7 /
Java created
SQL>
SQL> create or replace procedure test_java is
2 language java name 'FirstJava.test()';
3 /
Procedure created
SQL> exec hello;
PL/SQL procedure successfully completed
5.外联接提高表连接的查询速度? 望大家踊跃帮忙解惑!谢谢!
1.16进制数在转化成10进制数时出错SQL> select to_char(125,'xxxx') from dual;
TO_CHAR(125,'XXXX')
--------------------------------------------------------------------------------
7d
SQL> select to_char(7d,'xxx') from dual;
TO_CHAR(7.0E+000D,'XXX')
--------------------------------------------------------------------------------
7SQL> select to_char(to_char(125,'xxxx'),'xxx') from dual;
select to_char(to_char(125,'xxxx'),'xxx') from dual
ORA-01722: 无效数字2.索引高度是什么一个概念: pga_aggregate_target?
3.analyze index indexname validate structure有什么用?--判断是否需要重建索引?
4.以下代码怎样才能输出“Test successed!”SQL> set serveroutput on;
SQL> create or replace and compile java source named test_java as
2 public class FirstJava{
3 public static void test(){
4 System.out.println("Test successed!");
5 }
6 };
7 /
Java created
SQL>
SQL> create or replace procedure test_java is
2 language java name 'FirstJava.test()';
3 /
Procedure created
SQL> exec hello;
PL/SQL procedure successfully completed
5.外联接提高表连接的查询速度? 望大家踊跃帮忙解惑!谢谢!
内层转换后为字符串'7d',并不能自动转换为数字型,如果为常量7d则是双精度常量7
你这个类似select to_char('7d','xxx') from dual;是不行的2、索引高度是什么一个概念
索引高度是从索引根块到叶子块遍历所需的块数,其为BLEVEL-1
索引与pga_aggregate_target没有关系,这个参数是设置pga自动管理大小值3、analyze index indexname validate structure有什么用?
分析索引,是用来分析索引的数据块是否有坏块,以及根据分析得到的数据(存放在index_stats)來判断索引是否需要重新建立。4、怎样输出
设置输出缓冲
sql>call dbms_java.set_output(5000);5、外联接提高表连接的查询速度?
这儿的外联接应该不是outer join的意思,应该是如果有有子查询的话,可以尽量使用两表连接方式来查询数据,而非子查询。