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Filter data This chapter will teach you how to specify search criteria using the WHERE clause of a SELECT statement. Use WHERE clause Databases generally contain a large amount of data and rarely need to retrieve all rows in the table. Usually, only part of the table data will be extracted according to the requirements. To retrieve only the ...

sql language Overview and function **Overview: * * structured query language is abbreviated as SQL, and SQL statement is a language for database operation. **Function: * * you can add, delete, modify and query the data in the database, tables and tables in the database management system through Sql language. <br/ > sql classification ...

The original content of GreatSQL community cannot be used without authorization. Please contact Xiaobian and indicate the source for reprint.Content outline1, Test environment construction2, Execute process resolution3, Precautions1, Test environment constructionFirst, create a table and insert several rows of data fields:CREATE TABLE t (s1 INT ...

1.5.sql optimization 1.5.1. Check the execution frequency of sql After the MySQL client is successfully connected, you can view the server status information through the show [session|global] status command. You can view the main operation types on the current database by viewing the status information. --The following command displays the ...

Introduction: SQL optimization is the most important part of database performance optimization. The key of SQL optimization is inseparable from three points: table connection mode, access path and execution order. This paper focuses on several common connection modes. For multi table Association query, the execution steps of the query optimize ...

The original content of GreatSQL community cannot be used without authorization. Please contact Xiaobian and indicate the source for reprint.In the near future, we plan to create a docker image of GreatSQL to facilitate community users to use GreatSQL.The environment for making docker images is based on CentOS 7.9:[root@greatsql]# cat /etc/redh ...

1. What is a data connection pool Database connection pool( Database Connection Pooling)When the program is initialized, a certain number of database connection objects are created and saved in a memory area, which allows the application to reuse an existing database connection instead of re establishing one; Release the database connection ...

catalogue 1, What is JDBC 2, Working principle and advantages of JDBC 3, JDBC Usage Summary 1. Create database Connection 2. Create operation command Statement 3. Use the operation command to execute SQL 4. Process ResultSet 5. Release resources Specific implementation code: 4, JDBC common interfaces and classes 1.JDBC API 2. Databa ...

Case has two formats: simple case function and case search function. – simple Case function The function of a simple Case expression is to use the expression to determine the return value: select id,name, case sex when '1' then 'male' when '2' then 'female' else 'other' end from student – search Case function: Case function (c ...

🏷️ The current chapter is [MySQL basics] 07: view 🤖 🏷️ More: MySQL basic tutorial , take you to start MySQL database on a zero basis! 💪 🏷️ Welcome to praise 👍 Collection 🌟 Attention ❤️ Leaving a message. ✍️ Concept of view A virtual table composed of data queried by one or more tables in a database according to specific cond ...