SEARCH KEYWORD -- mysql

  <=> operator in MySQL

Have you ever seen "<=>" in a SQL query while using MySQL? Does it mean less and equals to and greater than? Actually if you consider it as the union of <= and =>, great, you are close to it. This is one form of equal operator in MySQL, it has the similar meaning to the = operator with some subtle difference. According to MySQL documentation, <=> is NULL-safe equal. This operator performs an equality comparison like the = operator, but returns 1 rather than NULL if both operand...

   MySQL,NULL safe,<=>     2014-03-24 06:23:22

  How MySQL optmizes ORDER BY

In some situations, MySQL will just use an index to fulfill the requirement of an ORDER BY or GROUP BY statement without extra sorting. Although ORDER BY will not have the exact match with index, index can still be used as long as the portion that is not included in the index is included in the where clause. The following queries will all use index to process the ORDER BY or GROUP BY part: SELECT * FROM t1 ORDER BY key_part1,key_part2,... ;SELECT * FROM t1 WHERE key_part1=constant ORDER BY key_p...

   MySQL,index,ORDER BY,optimization     2012-11-13 11:01:05

  How to reset root password in MySQL 8

The user password in MySQL is stored in the user table, the password reset is actually to change the value of record in this table. To change the password in case the password is forgotten, the idea is to bypass the authentication of MySQL and get into the system and update the record password value with SQL command. In MySQL 5, one can start MySQL service with --skip-grant-tables option, this option will tell the service to skip loading the grant tables when starting, hence the root user can lo...

   MYSQL,PASSWORD,MYSQL 8     2018-12-24 21:27:13

  Inline IF and CASE statements in MySQL

There are times where running IF statements inside a query can be useful. MySQL provides a simple way to do this through the use of IF and CASE statements. The IF statement takes three arguments; the conditional, the true value and the false value. False and true values may be static values or column values. For example: SELECT IF(score > 100, 100, score) AS score FROM exam_results this will return the value in the score column limited to a maximum value of 100. IF statements can a...

   MySQK,IF,Condition,CASE,SQL     2012-04-22 10:37:01

  JSP connect MySQL

To connect MySQL with Java Server Page(JSP). Some steps should be followed:Step 1: Download MySQL JDBC connector driver from the Internet. URL:  http://dev.mysql.com/downloads/connector/j/Step 2: Put the jar file downloaded in Step 1 in the Tomcat common lib folder and add this jar file to the CLASSPATH so that the JSP page can find the specified class.Step 3: Create the JSP page with MySQL connection : Example is shown below:        <% String driver="com.mysql.j...

   MySQL,JSP,Connection,Driver,Download     2011-05-11 10:04:57

  Using MySQL Connector/C++ with Visual Studio 2010

MySQL Connector/C++ is one of the latest connectors for MySQL, developed by Sun Microsystems. The MySQL connector for C++ provides an object-oriented application programming interface (API) and a database driver for connecting C++ applications to the MySQL Server.When we want to build a database application with C++ using Visual Studio 2010, we may use the MySQL Connector/C++, but sometimes we may encounter different errors, either compile or runtime error. After tried many times, I finally made...

   MySQL Connector,C++,Visual Studio 2010,VS2010     2012-06-01 13:52:20

  How Do I Enable Remote Access To MySQL Database Server?

By default remote access to MySQL database server is disabled for security reasons. However, some time you need to provide remote access to database server from home or a web server. If you want to remotely access to the database server from the web server or home, follow this quick tutorial.MySQL Remote AccessYou need type the following commands which will allow remote connections.Step # 1: Login Using SSH (if server is outside your data center)First, login over ssh to remote MySQL database ser...

   MySQL,Remote access,Enable,Host or webdomain     2011-10-31 00:31:41

  mysql – connection example

Mysql is a database, and to gain access to the data within C++ you will need to be able to “talk” to the database via queries (just like on the mysql command line interface e.g. select * from tablename), the connection process is very similar to the command line interface you will need to supply connection details as in hostname (localhost normally), username, password, database to use and also there are other details that you can pass e.g port number more information can be gained f...

   C++,Database,MySQL,Connection,Example     2011-10-29 00:42:10

  Work with MySQL character set and collation

For non-English websites, they often have to deal with character set and collation if they want to store data to and read data from databases with other languages. Character set tells the database which kind of character encoding scheme to use to store or read data, collation can be simply understood as a subset of character set, it tells the database how to sort data. We talk about working with character set and collation of MySQL today.  In MySQL, if we want to store Chinese, Japanese or ...

   MySQL,character set,collation,Chinese,question mark     2012-06-17 07:07:28

  One Way to Quickly Locate SQL with High CPU Usage in MySQL

When the CPU usage of a MySQL database rises abnormally, it's necessary to quickly identify the problematic SQL statements. In this post, we try to provide one way to achieve this.  Below are the actual steps. 1. Use the top command to find the threads with the highest CPU usage in the MySQL process. # Find the MySQL process ID ps -ef | grep mysql # Use the process ID to find the thread IDs with the highest CPU usage: top -H -p In top, press P to sort by CPU usage. Note the thread ID, fo...

   MYSQL,DEBUG,HIGH CPU,SLOW QUERY     2024-08-01 21:25:48

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