MyBatis - Associated Query
When the query content involves multiple tables with association, it is necessary to use association query. According to the relationship between tables and tables, Association queries can be divided into four types:
One-to-one Association query
One-to-many Association queries
Many-to-one Association query
Posted on Sun, 23 Jun 2019 15:09:43 -0400 by pmcconaghy
gii auto-generation method for getting associated data
If the database already has foreign key associations between tables, gii will automatically generate data methods to get other tables by using gii to model them.If the author_id field in the Post article table is associated one-to-one with the primary key of the User table, it will be ge ...
Posted on Sun, 23 Jun 2019 12:37:11 -0400 by compsci
11. Backup and Recovery
This chapter describes backup and recovery of database and user data in GPDB system.
GP recommends backing up the database regularly. Backup can be used to restore and rebuild the GPDB system in case of system failure or data corruption. In addition, you can use backup to migrate GPDB data from one system to another.
Posted on Sat, 22 Jun 2019 14:37:45 -0400 by lrsdsout
Because you want to test sql's optimization under tens of millions of levels of data, prepare to insert 10 million pieces of data into your Aliyun database, and search the Internet in a messy way, so you do it yourself, and also want to share it with you, the inadequacies are also for your advice.
1. Create partial tables
Posted on Sat, 22 Jun 2019 13:39:15 -0400 by ArmanIc
Java Web Development Knowledge Summary (Oracle-Object)
1. View: Oracle and mysql are common
1.1 View Overview
View is a kind of database object, which is a virtual table derived from one or more data tables or views. The data corresponding to the view is not really stored in the view, but in the referenced data table. The structure and ...
Posted on Fri, 21 Jun 2019 15:16:13 -0400 by netrepsa
PLSQL is Oracle's procedural extension of sql
Refers to the addition of process processing statements (such as branches, loops, etc.) to the SQL command language to enable the SQL language to process.
PL/SQL Program Structure
Description section (variable description, cursor declaration, excepti ...
Posted on Fri, 21 Jun 2019 12:16:03 -0400 by Syntax
- Restore content to start
Today, I wrote a long page, Baidu many are not very good. Net example, today I will update a page on layuiTable.
First, you need to understand the Table paging section of layui's official document. I attach here the address https://www.layui.com/doc/modules/table.html for you to see my example and lay document anyti ...
Posted on Thu, 20 Jun 2019 16:23:19 -0400 by everisk
High water level in surface space:
_The minimum size of a table space for creating a DMS is six EXTENTs. For DMS table spaces, containers can be removed from the table spaces or reduced in size. Use the ALTER TABLESPACE statement to complete this operation. Only when the number of extended data blocks deleted by this operation is less than or ...
Posted on Wed, 19 Jun 2019 20:44:28 -0400 by rdoylelmt
Database Name Remarks Last Modification Time DB_TEST Test Library 2017/6/23
Table Samples and Specifications Topic Classification
Number formula = ROW()-4
Types only allow varchar, nvarchar, int, tinyint, bigint, datetime, decimal
Length varchar, nvarchar, decimal can set length
The default values of char class are double single quotes ...
Posted on Wed, 19 Jun 2019 19:29:29 -0400 by koopmaster
PostgreSQL, multi master, logical subscription
Many businesses require more activities, but the most difficult thing to deal with is the database. Most businesses divide data into different IDCs according to UID, for example. The data of the same UID will always be written to one IDC, and then copy the corresponding data to ...
Posted on Wed, 19 Jun 2019 19:01:32 -0400 by Aimless