oracle 教程http://www.cuug.com/一.SQL*PLUS中输入SQL> conn as sysdba;SQL> alter system setjob_queue_processes = 6; --自动执行数据收集时该参数需要大于0SQL> alter system set timed_statistics =true; --使用statspack收集统计信息时建议...【阅读全文】
oracle:
conn hr/hr
SELECT count(*)+1 FROM employees
WHERE employee_id<(SELECT employee_id FROM employees WHERE first_name='Pat' and rownum=1);
SQL:
SELECT
COUNT(*)+1
FROM t144a
WHERE id < ( SELECT id FROM mynews WHERE name="abb" LIMIT 1);
首先,查【阅读全文】
Beginning
with Oracle10G, when statistics are gathered for a table, the old statistics are
retained so should there be any problem with performance of queries dependent
on those statistics, the old ones can be restored.How
long does Oracle retain the statistics for ?
The
default peri【阅读全文】
You cannot export any schema that contains dictionary metadata. This is a
restriction of export process.Schemas that exclusively contain
dictionary objects like SYS, CTXSYS, MDSYS and ORDSYS are never exported nor
imported. This is because these schemas are created when you install the related【阅读全文】