The Use and Trade-offs of Foreign Keys in Databases
There is debate over whether foreign keys should be used in database design. While foreign keys ensure data integrity, they introduce issues such as reduced write performance, increased system coupling, high operational risks, poor flexibility, uncontrollable cascading operations, failure in distributed scenarios, and redundant validation with the application layer. The alternative is to ensure data integrity at the application layer. Foreign keys may be considered for small systems, but modern high-concurrency systems often avoid them. The essence lies in balancing the database's strong constraints with system performance and flexibility.
Read MoreImplementing MySQL Database Master-Slave Replication
This document provides a detailed introduction to how to configure Master-Slave Replication in MySQL database, accompanied by configuration steps and simple test cases. The key points summarized are as follows: ### Configuration Steps #### 1. Select servers as master and slave - Choose one MySQL server as the master and another as the slave. #### 2. Setup on the master server - First, add the following configurations to the master's `/etc/my.cnf` or `my.ini` configuration file:
Read MoreSQL Format Notes
This content mainly introduces the basic SQL statements for creating, modifying, and deleting tables, as well as data querying, inserting, updating, and deleting. First, when creating a table, you need to define the data types and constraints of columns; for modifying a table, you can add or delete columns/constraints, or change the properties of columns; for deletion, you can directly use the `drop table` command and optionally cascade delete related dependencies. Query statements use the `select` keyword to retrieve data from specified tables and support grouping and sorting. In addition, various conditional expressions are also introduced, such as `like`, `insert into...value` (note: the original text may have an incomplete `insert into...value` statement, which has been retained as is).
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