how to check if mysql query returns nothing

mysql| Reference | Reference Manual | cache | Chinese MySQL 4.1.0 chinese reference manual---dog (heart sail) Translate MySQL Reference Manual for version 4.1.0-alpha. 6.9 MySQL Query Cache Starting with MySQL 4.0.1, MySQL server has an

18.2.1 MySQL server has gone away errors related to Lost connection to server during query. The most common cause of the MySQL server has gone away error is that the server times out and closes the connection. By default, if nothing happens, the

This article transferred from: HTTPS://WWW.TUICOOL.COM/WX/2EMBFMQObjectiveTalking about MySQL query optimization, I believe you have a collection of artifice: You cannot use SELECT *, do not use null fields, reasonably create an index, select the

MySQL basic and MySQL C API programming One, MySQL for Windows installation: 1. Download:The Officer network download can:http://www.mysql.com/downloads/2. Installation:There is nothing to say, a fool, and nothing to pay attention

1. Export the entire database Mysqldump-u user name-p--default-character-set=latin1 Database name > exported file name (database default encoding is latin1) Mysqldump-u wcnc-p SMGP_APPS_WCNC > Wcnc.sql 2. Export a table Mysqldump-u user name-P

First, we take the following steps: (1) connecting the database, (2) establishing the pointer, (3) inserting the record through the pointer, and (4) submitting the insert result to the database. >>> #导入模块 >>> import mysqldb >>> #连接数据库 >>> conn =

Groupadd mysql Create a user group named mysql Useradd-g mysql Create a user named mysql under the mysql user group Gunzip | mysql-VERSION.tar.gz | tar-xvf- Decompress the downloaded .gz File Cd mysql-VERSION Enter the decompressed directory CFLAGS =

ObjectiveTalking about MySQL query optimization, I believe you have a collection of artifice: You cannot use SELECT *, do not use null fields, reasonably create an index, select the appropriate data type for the field .... Do you really understand

Explanation of the usage of explain in mysql MySQLexplain BitsCN.com The explanation of mysql explain is clear.Of With the help of explain, you will know when to add an index to the table to use the index to search for records so that select can run

I. Overview of optimizationThe MySQL database is a common two bottleneck that is CPU and I/O bottlenecks, when the CPU is saturated when the data is loaded into memory or read from disk. Disk I/O bottlenecks occur when the load data is much larger