Programmer Think

JDBC is the cornerstone of java accessing database. JDO, Hibernate, MyBatis, etc. all encapsulate JDBC. If you only use the persistence layer framework, you don't need to learn JDBC, but from the perspective of the development prospect of programmers, you must master it. The framework will be updated iteratively all the time, but the pri ...

We have learned the basic query statements. Next, we set foot in the query of conditional statements and keep up with me! Advanced level 2: condition query grammar SELECT query list FROM table name WHERE filter criteria; classification 1. Filter by conditional expression: > < = < > =<= 2. Filter by logical express ...

1, Stored procedure 1.1 overview of stored procedures Stored Procedure is Stored Procedure in English. Its idea is very simple, which is the encapsulation of a set of precompiled SQL statements. The stored procedure is stored on the MySQL server in advance. When it needs to be executed, the client only needs to issue a command to call the stor ...

Previously, we learned the design rules of relational database: Follow the ER model and three paradigms (E entity represents the meaning of entity, corresponding to a table in the database; R relationship represents the meaning of relationship.)Three paradigms: 1 Column cannot be disassembled 2 Unique identification3 The relationship refer ...

1, Multi table join query method If the information source of the query is multiple tables, a multi table connection query can be established by connecting two tables. Syntax: SELECT feldlist FROM table1 JOIN table2 ON table1.column1=table2.column2_1 JOIN table3 on mable2.colamn2_2=table3.column3[where condition] In daily data query appl ...

This project is based on Django. Due to the interface related development, the front-end development is not involved for the time being. MySQL is used at the back end for data storage, addition, deletion, modification and query. 1) What is Django? Django is a free and open source Web framework developed in python. It provides many mod ...

1. Understand the principle of MySQL master-slave replication. Mainly based on MySQL Binary log It mainly includes three threads (2 threads) I/O Threads, 1 individual SQL Thread) 1 , MySQL Record the data changes in the binary log; 2 , Slave take MySQL Copy binary lo ...

Multi table relationship One to many relationship concept The one to many relationship means that one row of data in the master table can correspond to multiple rows of data in the slave table at the same time. In turn, it means that multiple rows of data in the slave table point to the same row of data in the master table Application scena ...

1, LAMP overview LAMP architecture is one of the mature enterprise website application modes at present. It refers to a complete set of systems and related software working together, which can provide static and dynamic Web site services and its application development environment.LAMP is an abbreviation, including Linux operating system, ...

In the process of application development, due to the small amount of data in the initial stage, developers pay more attention to the realization of functions when writing SQL statements. However, after the application system is officially launched, with the rapid growth of production data, many SQL statements begin to show performance problems ...