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Technical articles with clear explanations and examples
How To Check MySQL Version
Let us understand how to check the version of MySQL that the user is currently running −Before entering queries on the console, it is important to ensure that the user is connected to the server.Check MySQL VersionThe below query would give the version number of the server being used, and the current date.mysql> SELECT VERSION(), CURRENT_DATE;Note: The function ‘VERSION()’ and ‘CURRENT_DATE’ are case −insensitive. This means ‘version()’, ‘Version()’, ‘vERsion()’, all mean the same. Same goes with ‘CURRENT_DATE’QueriesLearn about MySQL QueriesAn SQL query is followed by a semi−colon.When a query is issued to mysql, it sends the query to the server ...
Read MoreInstalling MySQL from source on linux
Linux supports many different methods to install MySQL. Only one of the distributions from Oracle needs to be used out of the many installations available.StepsType − Apt, set up method−Enable the MySQL Apt repositoryType − Yum, set up method−Enable the MySQL Yum repositoryType − Zypper, set up method−Enable the MySQL SLES repositoryType − RPM, set up method−Download a specific packageType − DEB, set up method−Download a specific packageType − Generic, set up method−Download a generic packageType − Source, set up method−Compile from sourceType − Docker, set up method−Use Docker Hub for MySQL Community Edition; download Docker image for MySQL Enterprise ...
Read MoreDealing with Problems Compiling MySQL
Some problems with compiling MySQL could be because of not configuring properly. Hence, the solution is to reconfigure.If CMake is run right after it was previously run, there is a possibility that it would use information that was gathered from its previous call. This information is present in CMakeCache.txt. When CMake begins, it looks for this file and reads the contents (if it exists), assuming that the information is correct. This assumption becomes wrong when the file is reconfigured.Each time CMake is run, ‘make’ has to be executed again to recompile. The old object files from previous builds can be ...
Read MoreGetting Information About MySQL Databases and Tables
It is possible for the user to forget the name of the database or table or the structure of table or the name of the columns. This issue can be solved using MySQL since it supports many statements that provide information about the databases and tables which it supports.The ‘SHOW DATABASES’ query can be used to list all the databases that are managed by the server. To see which database is currently in use, the ‘DATABASE()’ function.Let us understand this query in the below section −Querymysql> SELECT DATABASE();Output+---------------------+ | DATABASE() | +---------------------+ | databaseInUse ...
Read MoreList down all the Tables in a MySQL Database
Let us understand how to list down all the tables in a MySQL database −Once a database is created, we can access and use a specific database, using the following query −Querymysql> USE databaseName Database changedThe ‘USE’ statement doesn’t require a semi-colon. This is similar to the ‘QUIT’ statement. Even if semi-colon is used, it does no harm. We can create and use a database of our own, but before that, MySQL administrator’s permission is required.The MySQL administrator can execute a command as shown below to provide permissions −mysql> GRANT ALL ON tableName.* TO ‘your_mysql_name’@’your_client_host’;Here, ‘your_mysql_name’ refers to the MySQL ...
Read MoreConnect to MySQL database from command line
Let us understand how MySQL can be connected to the database using the command-line. This is done for clients like mysql or mysqldump.The below command invokes mysql without specifying any explicit connection parameters −mysqlSince there are no parameter options, the default values will be applied −The default host name is localhost.The default user name is ODBC on Windows.No password is sent because neither --password nor -p has been mentioned.For mysql, the first non-option argument is considered the name of the default database. Since there is no such argument, mysql selects no default database.To specify the host name, user name and ...
Read MoreGetting Minimum and Maximum Value in MySQL
We need to use the MAX(columnName) to find the Maximum value in a column, whereas use the MIN(columnName) to find the Maximum value in a column.Let’s say following is the syntax to find the highest and lowest value in a specific column −mysql> SELECT @min_val:=MIN(columnName), @max_val:=MAX(columnName) FROM tableName; mysql> SELECT * FROM tableName WHERE columnName=@min_val OR columnName=@max_val;Note: Let’s say we have a database named ‘StudentsRecords’ and a table named ‘STUDENT.Following is our table −StudentIdStudentMarksS00190S00297S00372We will now write the query −Querymysql> SELECT @min_val:=MIN(StudentMarks), @max_val:=MAX(StudentMarks) FROM STUDENT; mysql> SELECT * FROM STUDENT WHERE StudentMarks =@min_val OR StudentMarks =@max_val;Output+---------------------+ | StudentMarks ...
Read MoreThe Row Holding the Maximum of a Certain Column in MySQL
Let us understand how to find the row that holds the maximum of a specific column in MySQL −Note: We assume we have created a database named ‘DBNAME’ and a table named ‘tableName’.Let us see how to fetch the row that holds the maximum value of a specific column using a MySQL query −This can be done using the subquery. Here, we are fetching the maximum value of colName3 −QuerySELECT colName1, colName2, colName3 FROM tableName WHERE colName3=(SELECT MAX(colName3) FROM tableName);Output+--------------+--------------+--------------+ | colName1 | colName2 | colName3 | +--------------+--------------+--------------+ ...
Read MoreFind the Maximum Value in a Column in MySQL
We need to use the MAX(columnName) to find the Maximum value in a column. But, at first, we will understand about database and tables in MySQL.Before installing MySQL, it is important to determine which version and which distribution format (it could be a binary file or from source files) should be used. If the database was newly created, it is obvious that there would be no tables in it.One of the most important part is to decide the structure of the database, the tables that would be needed, the columns in every table and the relationship between these tables. Once ...
Read MoreUsing MySQL with Apache
Let us understand how to use MySQL wth Apache −Apache is a web server software which is developed and maintained by Apache software foundation. It is a software that takes requests from user to access a web page.A few security checks are performed on the HTTP request and then takes the user to the web page. There are many programs that allow authentication of the users from a MySQL database. These programs can also be used to write the log files into a MySQL table.The Apache logging format can be easily changed into readable mode by using MySQL, and putting ...
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