Programmer Think

Before  , there was a small test project that needed to synchronize some local data to Alibaba cloud database regularly. It was implemented by executing LOAD DATA with the most mechanical script. Here is a brief introduction. LOAD DATA can quickly read text file data into the table (LOAD DATA is us ...

Catalogue 1. Textbook [P281-P287] 2. SQL statement [create data table (6 tables), insert data] 2.1. Chinese field representation 2.2. English field representation 3. New view 3.1, 6 table general view 3.2. Total credits (student number, credits) 3.3. Total credit statement 4. Query exercise 1. Textbook [P281-P287] ...

SQL parsing order Next, let's take a look at the past and present life of an SQL statement. First, let's look at the sample statement: SELECT DISTINCT < select_list > FROM < left_table > < join_type > JOIN < right_table > ON < join_condition > WHERE < wh ...

Before moving on to dynamic sql, let's start by saying that a user's id in real development is usually out of order, such as random generation using UUID s. Write one below. public class UUIDGenerate { public static String getIdByUUID(){ return UUID.randomUUID().toString().replaceAll("-" ...

Content Summary constraint condition Relationships between tables (constraints) Modify the full syntax of the table Copy Table constraint condition Default default """ # Supplement: You can specify fields when inserting data create table t1 ( id int, name varchar(16) ); insert into t1 (name, id) values ('samuel', 1); create table ...

Before, ID was implemented with auto increment. Now I want to use Snowflake algorithm to generate primary key. What changes should I make? catalog Background Implementation plan Scenario 1 - add primary key manually Scenario 2 - override save() method Scenario 3 - using pre in Django Signals_ save() ...

Our debugging environment: Debug code: public class MyaaTest { public static void main(String[]args) { String resource = "config.xml"; try { //1. Read configuration file InputStream in= Resources.getResourceAsStream(resource); SqlSessionFactor ...

The data source module for Mybatis is located inOrg.apache.ibatis.datasource. Common data source components are implementedJavax.sql.DataSourceInterface.Within Mybatis, third-party data source components are integrated, and data source implementations are provided.In general, data source initializat ...

Mysqldump is a logical backup method. Its biggest defect is that the speed of backup and recovery is slow. For a database less than 50G, this speed is acceptable. But if the database is very large, it is not suitable to use mysqldump backup again. At this time, you need a kind of easy-to-use and efficient tool. Xtrabackup is one of them, known ...

On Jetpack(1) - ViewModelOn Jetpack(2) - LifecyclesOn Jetpack(3) - LiveDataDemo project Although Android carries SQLite, its operation is troublesome, and if it is a large-scale project, it will become confusing and difficult to maintain, unless you design a very good architecture and package. Of cour ...