Execution plan optimization example
1. Phenomena Execute the following code and find that the sub-inventory table has been scanned SELECT msi.secondary_inventory_name , --Subinventory msi.description --Inventory description FROM inv.mtl_secondary_inventories msi ,csi_item_instances cii WHERE msi.secondary_inventory_name = cii.invUTF-8...
Posted by apocryia on Thu, 27 May 2021 04:04:49 +0930
Plain text analysis to extract all source table names from complex sql query statements
How to extract all source table names from complex sql query statements This article uses Python implementation 1. Background A small tool has been developed to detect some sql scripts, and there is a step to extract the source tables of a query statement.It is possible to use the database, butUTF-8...
Posted by poujman on Tue, 08 Jun 2021 01:49:48 +0930
SQL optimization (take Mysql as an example, Oracle can refer to)
This blog is mainly aimed at Mysql5.X version If the content of this blog is incomplete, please see the official website https://dev.mysql.com/doc/refman/8.0/en/optimization.html 1, Reasons for SQL optimization Low performance, long execution time, long waiting time, poor SQL statement (connectUTF-8...
Posted by anita999 on Wed, 09 Jun 2021 07:40:48 +0930
oracle interview
database 1, where and having WHERE Used for row filtering. SQL Medium increase HAVING The reason is, WHERE Keyword cannot be used with aggregate functions. 2, String and date, number conversion between each other To string: to_char()；To date: to_date()；To number: To_number(char,'format')； 3,UTF-8...
Posted by PatriotXCountry on Sat, 10 Jul 2021 05:50:18 +0930
Oracle simple SQL statement
preface This article is a note I made when I was studying in station B. It mainly introduces some SQL statements of Oracle database. The database in this article is a built database, which is convenient for demonstration. This article is for reference only, no reprint! Tips: the following is tUTF-8...
Posted by nogeekyet on Wed, 21 Jul 2021 07:34:54 +0930
General format and notes of SQL update (INSERT,UPDATE,DELETE) statement
catalogue Write in front of the article About update statements INSERT statement UPDATE statement DELETE statement General considerations of UPDATE statement Write in front of the article From the perspective of SQL statement format, this paper discusses the basic format of SQL UPDATE statementUTF-8...
Posted by fiddy on Wed, 21 Jul 2021 08:29:33 +0930
Oracle Certified OCP From Getting Started to Abandoning 03-centos7 Installation of oracle12c
1. Write hosts file vi /etc/hosts 2. Close the firewall (1) Check firewall status first systemctl status firewalld.service We found the firewall open (2) Temporarily close the firewall Temporarily shut down the firewall, the firewall will still start when the system starts next time systemctl sUTF-8...
Posted by hesyar on Wed, 04 Aug 2021 01:40:17 +0930
PL/SQL basic operation example
1,PL/SQL PL/SQL(Procedural Language/SQL) is a procedural language. It is a procedural extension of oracle to SQL language. Process processing statements (branches, loops, etc.) are added to SQL command language, so that SQL language has process processing ability. It combines the data operatioUTF-8...
Posted by lhaynes on Sat, 07 Aug 2021 03:39:33 +0930
Oracle database backup and restore
Author: threedaymanSource: Hang Seng LIGHT cloud communityTheoretical preparationoracle database provides expdp and impdp commands to back up and restore the database.For details, please refer to the official oracle documentation https://docs.oracle.com/en/database/oracle/oracle-database/12.2/sUTF-8...
Posted by sinter4911 on Wed, 08 Dec 2021 14:55:24 +1030
Advanced database - JDBC, Maven
JDBC A set of database standards set by sun company, This standard is JDBC (Java Database Connectivity). However, it is only a specification without specific implementation. Therefore, database manufacturers implement their own Driver according to JDBC standards, such as MySQL Driver com.mysql.UTF-8...
Posted by trent2800 on Sat, 18 Dec 2021 04:15:45 +1030