Programmer Think

Basic Grammar Hello World of plsql set serveroutput on --Print Hello World declare --Explanation section(Variable, cursor or exception description) begin --Program body ( DML Statement) dbms_output.put_line('Hello World'); end; Use of basic variable types -- Use basic variable types declare --Define basic variable types ...

background There is a bug in the previously designed tranform, which can be solved by raising the limit, so learn the rules raised on calculate. By the way, it also lays a foundation for the elimination of public expressions later. rule UnionPullUpConstantsRule What did you do? It is not difficult to see from the name that the constant ...

1, Basic knowledge 1. Role of backup and restore: Backup mainly plays the role of data disaster recovery. It is an effective means to ensure data security in case of database failure; By restoring the backup set data, the data can be restored to the state before the database failure. 2. Basic principles of backup, restore and recovery: In D ...

1. Constraints 1.1 PrimaryKey(PK): primary key Features: unique + non empty, a table can only have one primary key constraint It is usually a numeric column Better be meaningless 1.2 NOT NULL Features: cannot be empty. We recommend that the business key column (index column) be set as non empty as possible 1.3 UNIQUE constraint Features: ...

Introduction to the Author Author: Lucifer Liu, member of the Chinese DBA Consortium (ACDU).Currently mainly engaged in Oracle DBA work, has been engaged in Oracle database development work, mainly serving the production and manufacturing, Automotive Finance and other industries.Now has Oracle OCP, OceanBase OBCA certification, good at Orac ...

1, What is a Session Session is an interface (HttpSession).A Session is a Session. It is a technology used to maintain an association between a client and a server.Each client has its own Session.In the Session session, we often use it to save the information after the user logs in. 2, How to create a Session and get (id number, new or not) H ...

In work, we delete data or database by mistake. Do we have to run away? I don't think so. Programmers must learn to save themselves and retrieve the data unconsciously. In MySQL database, we know that binlog logs record all our operations on the database, so binlog logs are a sharp tool for us to save ourselves. Today, taking MySQL databa ...

Tip: after the article is written, the directory can be generated automatically. Please refer to the help document on the right for how to generate it preface I saw it on the bus in the morning**_ The article on MySQL binlog written by yidianyu * * in Jiangnan is very detailed about the use of binlog to recover the database. I can under ...

Please read carefully and refer to the README document for the latest steps, processes and related requirements for the overall upgrade of Oracle 19c rac cluster from 19.3 opatch to 19.10. 1, View the current database patch version col ACTION for a8 col status for a15 set line 999 col ACTION_TIME for a30 col DESCRIPTION for a50 SQL> selec ...

The DBLINK built this time is to access the SQL SERVER database on the Win side of the Damon database on the Linux side. By configuring ODBC to connect to the SQL SERVER database, DM creates an ODBC DBLINK connection to realize the DBLINK between DM and SQL SERVER. The following are the specific operation steps. DBLINK overview: DBLINK (Datab ...