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如果在SQL语句的where子句中写的SQL代码不合理,就会造成优化器删去索引而使用全表扫描,一般就这种SQL语句就是所谓的劣质SQL语句。在编写SQL语句时我们应清楚优化器根据何种原则来使用索引,这有助于写出高性能的SQL语句。SQL语句的编写原则和SQL语句的优化,请跟我一起学习以下几方面: 不要让Oracle做得太多 避免复杂的...
建表sql如下: 代码语言:javascript 代码运行次数:0 运行 AI代码解释 create table t_operate_log ( id number(7), type varchar(1), op_time date ) PARTITION BY RANGE(op_time) ( partition t_operate_log_1 values less than (to_date('2019-01-17','yyyy-MM-dd')), partition t_operate_log_...
select s.sid,s.username,sw.event,sw.wait_time,sw.state,sw.seconds_in_wait from v$session s,v$session_wait sw where s.username is not null and sw.sid=s.sid and sw.event not like '%SQL*Net%' order by s.username; --求会话等待的file_id/block_id col event format a24 col p1text ...
oracleReaderQuery使用自定义 SQL 查询读取数据。 例如"SELECT * FROM MyTable"。 启用分区加载时,需要在查询中挂接任何相应的内置分区参数。 有关示例,请参阅从 Oracle 进行并行复制部分。否 convertDecimalToInteger使用零标度或未指定标度的 Oracle NUMBER 类型将转换为相应的整数。 允许的值为true和true(默认值)...
Oracle SQL-根据当前日期更改WHERE条件 我有一张类似的表 TradeDate | Widgets 12-DEC-2020 6 13-DEC-2020 3 13-DEC-2020 9 14-DEC-2020 3 15-DEC-2020 12 15-DEC-2020 4 ... 08-JAN-2020 11 ... 我想编写一个每日查询,根据今天的日期返回结果集。如果今天的日期是25-DEC-2020或01-JAN-2020,...
Oracle TimesTen In-Memory Database SQL Reference Guide Release 7.0 B31682-01 Copyright ©1996, 2007, Oracle. All rights reserved. ALL SOFTWARE AND DOCUMENTATION (WHETHER IN HARD COPY OR ELECTRONIC FORM) ENCLOSED AND ON THE COMPACT DISC(S) ARE SUBJECT TO THE LICENSE AGREEMENT. The ...
You can change the format you use for inserting dates for an instance by changing the NLS_DATE_FORMAT parameter for the instance. You can do this for a session by using the ALTER SESSION SQL statement or for a specific value by using parameters with the TO_DATE expression in your SQL sta...
oracleReaderQuery Use the custom SQL query to read data. An example is "SELECT * FROM MyTable".When you enable partitioned load, you need to hook any corresponding built-in partition parameters in your query. For examples, see the Parallel copy from Oracle section. No convertDecimalToInteger...
Learn how to convert Oracle database objects to SQL Server database objects with SSMA for Oracle, after you set options and connect to Oracle and SQL Server.