After the database has been running for some time, the table space has been increasing, but the actual amount of data is not so large. Deleting data or truncate tables does not reduce the tablespace. This is because when the table space is insufficient, it will expand automatically, but it will not shrink automatically.
terms of se ...
Posted by lorewap3 on Wed, 18 May 2022 03:56:25 +0300
Installation of Oracle Database 11g Enterprise on CentOS
VMware Workstation 15 Pro
CentOS 7 64 bit (CentOS-7-x86_64-DVD-1810.iso)
If the environment is not ready, you can refer to: Installing CentOS for VMware virtual machines
Navicat Premium 12
Oracle Databa ...
Posted by sy-co on Tue, 10 May 2022 21:06:46 +0300
When the queried data does not come from one table, you need to use multi table join to complete the query. Query the associated data according to the relationship between the data in different tables.
1, Cartesian product
In mathematics, the Cartesian product of two sets X and y, also known as the direct product, repr ...
Posted by grafnic1732 on Sun, 08 May 2022 20:34:12 +0300
Author: Yao yuan
Focus on Oracle and MySQL databases for many years, Oracle 10G and 12C OCM, MySQL 5.6, 5.7, 8.0 OCP. Now Dingjia technology serves as a technical consultant to provide database training and technical support services for colleagues and customers.
Source of this article: original contribution * produced by aikesheng o ...
Posted by squalls_dreams on Sun, 08 May 2022 03:53:20 +0300
Installing oracle on linux is often used in actual operation and maintenance. Just recently, I reinstalled the system. By the way, I recorded the whole process of installing oracle.
Different environments may have small differences, which are similar. To prevent influence, the version information I use is give ...
Solving the problem of slow query speed of Oracle data volume above 10 million
1. Change the original table to a partitioned table
1.1 partition table judgment
1.2 reconstruction zoning table
1.2.1 rename the original watch
1.2.2 reconstruction of zoning table
1.2.3 copying data
2. Create index
2.1 launch execution plan
2.2 no ...
Posted by Mundo on Fri, 22 Apr 2022 04:12:11 +0300
SQL standard added a new data operation statement in 2003: MERGE, which can complete the operation of INSERT statement, UPDATE statement and even DELETE statement at the same time.
Standard merge statement
Its basic syntax is as follows:
MERGE INTO target [AS t_alias]
USING source_table [AS s_alias]
WHEN MATCHED THEN
Posted by lobo235 on Tue, 19 Apr 2022 07:06:17 +0300
Three tier architecture
Layered mode Layered mode is the most common architecture mode The layered pattern is the foundation of many architectural patterns
Separate the components of the solution into different layers Maintain cohesion between components in the same layer Loose coupling between layers
Why do I need a layer ...
Posted by davo666 on Tue, 12 Apr 2022 08:42:59 +0300
What is a partition table? Why use partition table? How to create a partition table?
If the data in a table in your database meets the following conditions, you should consider creating a partitioned table. 1. There are a lot of data in a table in the database. What are many concepts? Ten thousand? 20000? One hundred thousand or one million? T ...
Posted by Garrett on Mon, 11 Apr 2022 09:20:24 +0300