Oracle Dataguard next block repair technology system data table

To test the scenario when the following system table OBJ $has bad blocks, can the database automatically repair the bad blocks? (I) database environment # Database version sys@ORCL> select * from v$version; BANNER -------------------------------------------------------------------------------- Oracle Database 11g Enterprise Edition Release ...

Posted on Sat, 07 Dec 2019 21:57:53 -0500 by stuartshields

Using JPA in SpringBoot

In the last article, we used the JdbcTemplate to access the database. After all, we used the native SQL form. I'm sure that lazy people like me won't consider it.. This record uses JPA to greatly reduce our code volume First, prepare the SQL file DROP TABLE IF EXISTS users; CREATE TABLE users ( id INT ( 11 ) PRIMARY KEY AUTO_INCR ...

Posted on Sat, 07 Dec 2019 19:49:01 -0500 by alwoodman

New feature of MySQL 8.0 -- invisible index

Characteristics of invisible index The indexes created by default are visible. If you need to create an invisible index, you need to specify the invisible parameter. The invisible index index cannot be used by default. You need to turn on the parameter optimizer  switch ='use  invisible  indexes = on 'to use it; If force index is used, it c ...

Posted on Sat, 07 Dec 2019 14:44:45 -0500 by LikPan

One SQL causes server overload

At about 9:30 in the morning, the salesperson reported that their page was opened slowly, and the subsequent page appeared 502. Then I receive the alarm and log in to the database server to check the cpu 400% load 30 or so Enter the database and find many slow queries It was thought that these slow queries came from the daily scheduled task ...

Posted on Sat, 07 Dec 2019 13:28:38 -0500 by Liquix

MySQL Index and Transaction, Storage Engine MyISA and InnoDB

MySQL indexes and transactions, views, storage engines MylSAM and lnnoDB The concept of index Indexes in databases are similar to catalogs in books: 1. - In this book, you don't have to read the whole book to use the catalog to quickly find the information you need.2. The table of contents in the book is a list of words with page numbers cont ...

Posted on Sat, 07 Dec 2019 03:42:09 -0500 by BigMike

Create a jdbc connection

This paper introduces how to establish a jdbc connection for database query. Create a java project and import the jar package. Using mysql database, the author needs mysql database driver jar package and jdbc connection jar package to establish jdbc connection.    The process of establishing a jdbc connection is as follows: 1. Load database d ...

Posted on Sat, 07 Dec 2019 02:08:08 -0500 by Barb54

Case: the driven table does not use the index, resulting in poor performance

problem The development of an insert SQL is a scheduled task. The content is as follows. It needs to be executed about 5-10 times a day. After running for a while from the select part, the author gives up and has no result. The efficiency is very poor INSERT INTO bs_sf_yd_flow_check (   `merchantNo`,   `sfBusinessId`,   `sfMerOrderId`,   `sfTr ...

Posted on Fri, 06 Dec 2019 13:29:05 -0500 by semlabs

[JavaSE] JDBC programming of Java

JDBC creation process Load database driver Create database connection Create operation command Execute SQL statement Process return result set Close result set Close operation command Close connection actual combat First load the driver Project right click to find Open Module Settings open After opening, do the following F ...

Posted on Fri, 06 Dec 2019 13:23:39 -0500 by snowdog

A solution to the error of return value of Oracle function called by C ා odp.net

Someone in the community asked: C ා cannot call the return value of the custom function in Oracle normally. But in PL/SQL, the normal call returns. So let's try: 1. Preparation function (Oracle 11g. 2.0.0.4) CREATE OR REPLACE FUNCTION F_Update_Grade(v_UserID in Number) return nvarchar2 is V_Grade nVARCHAR2(20); begin V_Grade := ' ...

Posted on Fri, 06 Dec 2019 08:23:47 -0500 by plapeyre

PHP realizes automatic login and registration of wechat code scanning, refer to the example

Wechat development is a basic technology that phper must master now. In fact, those who have done wechat development know that wechat interface is very powerful and simple. Let's take a look at an example of wechat automatic login and registration The scope of the interface for automatic login and registration of php wechat code scanning pc is ...

Posted on Thu, 05 Dec 2019 19:37:33 -0500 by Alffallen