MySQL Introduction Basic Grammar 1

I. Basic Use of MySQL 1.1 Basic operations on the command line Mysql-u username-p carriage return Enter password: xxx Enter the database (All commands in mysql end with a semicolon and enter help; query all mysql commands) 1.2 MySQL directory structure bin: All executable files exe File of MySQL InstanceConf ...

Posted by bruce080 on Wed, 22 May 2019 20:15:30 +0200

Analysis of SQL in a hang database

Someone at the interface came to me and said that there was a stored procedure that couldn't run and tried to report errors several times. ORA-12801: Error signal in parallel query server p001, instance xx ORA-04030: Insufficient process memory when attempting to allocate 16328 bytes (xxxx) It also monitors the receipt of spatially increasi ...

Posted by mxdan on Sun, 19 May 2019 22:34:38 +0200

oracle database index related knowledge

1. Index: Two new tables, T1 and T2, are created as follows: When both tables are queried the same way, the T1 table uses an index, but the T2 table does not scan the full table. select * from t1 where id=10; select * from t2 where id=10; This is mainly because the values of the clustering factor in the T1 table ...

Posted by ozzmans on Sun, 19 May 2019 11:42:35 +0200

DML for (MariaDB/MySQL): Data Update, Delete

Contents of this article:1.update statement2.delete statement 2.1 Form Delete 2.2 Multi-table Deletion3.truncate table 1.update statement update is used to modify records in a table. # Form update syntax: UPDATE [LOW_PRIORITY] [IGNORE] table_reference [PARTITION (partition_list)] SET col1={expr1|DEFAULT} [,col2={expr2|DEFAULT}] ...

Posted by thomashw on Sun, 19 May 2019 09:27:22 +0200

Java Develop - MySQL-based SQL protocol/optimized record

1.SQL protocol 1. Statute of Forms Required three fields: create table `demo` ( `id` bigint(32) not null auto_increment comment 'Primary key', `gmt_create` timestamp not null default current_timestamp comment 'Active Creation Time', `gmt_modified` timestamp not null default current_timestamp on update current_timestamp comment 'Passiv ...

Posted by AndyB on Sat, 18 May 2019 13:07:56 +0200

ORA-01779: Cannot modify columns corresponding to non-key saved tables

Today, Zhongshan company lets the dispatching arrangement batch be seen remotely, because it is the same source program, making the formal library will not report errors, making the test library will report errors, thinking of the problem of data or database settings, so it debugs the source program, and the program will report errors when it c ...

Posted by RedRasper on Sat, 18 May 2019 05:25:08 +0200

Let's talk about Java 8 Stream features

The Java 8 API adds a new abstraction called Stream, which allows you to process data in a declarative manner. Stream provides a high-order abstraction of Java set operations and expressions using an intuitive way similar to querying data from a database with SQL statements. Stream API can greatly improve the productivity of Java program ...

Posted by jesse_james on Thu, 16 May 2019 13:47:26 +0200

Performance testing and optimization of PostgreSQL 11 similar image search plug-in imgsmlr 2-single machine partition table (dblink asynchronous call parallel) (400 million images)

Label PostgreSQL, imgsmlr, GiST, image eigenvalues, wavelet transform background Continued "PostgreSQL 11 Similar Image Search Plug-in imgsmlr Performance Test 1 - Single Table (400 million images)" Parallel invocation using partition table + dblink asynchronous interface. (It's better to support imgsmlr gist index scan directly at ...

Posted by synapp2 on Wed, 15 May 2019 10:27:10 +0200

Start with declarative transactions based on @Transactional full annotation, and thoroughly understand the principles of Spring transaction management

Preface Previous article: Use of Spring-jdbc and 8 ways of managing Spring transactions (declarative + programmatic) Introduces many ways to use Spring transactions, including when it comes to the full comment @Transactional approach, so this article takes the @Transactional approach as a starting point to unravel the mystery of Spring ...

Posted by countcet on Wed, 15 May 2019 07:36:14 +0200

Basic usage of PostgreSQL

Preface PostgreSQL is an open source object relational database management system (ORDBMS). This paper aims to introduce some basic operations of PostgreSQL (hereinafter referred to as pg) for beginners'reference and reference. It should be noted that all the following operations were performed in Ubuntu 16.04, using version 9.6 of PG. For diff ...

Posted by may27 on Tue, 14 May 2019 20:20:13 +0200