Found 4220 Articles for MySQLi

Let us understand how option files can be used with MySQL programs −Most MySQL programs can read the startup options from option files, which is also known as the configuration files.Option files provide an easy way to specify commonly used options so that they need not be entered on the command line every time the user runs a program.To know whether a program reads option files or not, it can be invoked with the help of the −−help option.For mysqld, the −−verbose and –help can be used.If the program reads option files, the help message indicates the files that it ... Read More

Let us understand how to use options on command line for MySQL programs −The program options which are specified on the command line follow the below rules −The options are given after the command name.An option argument begins with one dash or two dashes, and this depends on whether it is a short form or long form of the option name.Many options have both short and long forms. Let us take an example to understand this − −? and −−help are the short and long forms of the option which instructs a MySQL program to display the help message.The option ... Read More

Let us understand how to specify options in MySQL programs. There are many ways in which options can be specified for MySQL programs −Command LineThe options on the command line after entering the program name have to be listed. This is a common step for options which applies to a specific invocation of the program.Option fileThe options in an option file which the program reads when it starts also needs to be listed. This is a common step for options that the user needs the program to use every time it runs.Environment VariablesThe options in environment variables need to be ... Read More

A MySQL program can be invoked from the command line (i.e, from your shell or command prompt).How to invoke?This can be done by entering the program name followed by any options or arguments that would be needed to instruct the program to do what the user wants.The below commands show some sample program invocations. The ‘shell>’ represents the prompt for the command interpreter; which is not part of what the user types. The specific prompt seen by user depends on their command interpreter.Typical prompts are $ for sh, ksh, or bash, % for csh or tcsh, and C:\> for the ... Read More

There are many programs in a MySQL installation. Let us see an overview of some of the programs. Some programs are platform−specific, which means they are not present in all of MySQL distributions.Every MySQL program takes different options. There is a ‘- - help’ option that can be used to get a description of the program’s different options. The default option values can be overridden for MySQL program, by specifying options on command line or in an option file.Every MySQL program takes different options. There is a ‘- - help’ option that can be used to get a description of ... Read More

The AUTO_INCREMENT attribute is used to generate a unique identify for new rows. If a column is declared as ‘NOT NULL’, it is possible to assign NULL to that column to generate a sequence of numbers.When any value is inserted into an AUTO_INCREMENT column, the column gets set to that value, and the sequence also gets reset so that it generates values automatically, in the sequential range from largest column value.An existing ‘AUTO_INCREMENT’ column can be updated that will reset the ‘AUTO_INCREMENT’ sequence as well. The most recent auto-generated ‘AUTO_INCREMENT; value can be retrieved using the ‘LAST_INSERT_ID()’ function in SQL ... Read More

Let us understand how to work with AUTO_INCREMENT columns in MySQL −The AUTO_INCREMENT attribute is used to generate a unique identify for new rows. Let us see how this statement works. Before that, consider the below query −QueryCREATE TABLE tableName (    id MEDIUMINT NOT NULL AUTO_INCREMENT,    name CHAR(30) NOT NULL, PRIMARY KEY (id) ); INSERT INTO tableName (name) VALUES (‘val1’), ('val2'), ('val3'), ('val4'); SELECT * FROM tableName;Output+----+---------+ | id | name | +----+---------+ | 1 | val1 | | 2 | val2 | | ... Read More

Let us understand how ATUO_INCREMENT works −The AUTO_INCREMENT attribute is used to generate a unique identify for new rows. Let us see how this statement works. Before that, consider the below query −QueryCREATE TABLE tableName (    id MEDIUMINT NOT NULL AUTO_INCREMENT,    name CHAR(30) NOT NULL,    PRIMARY KEY (id) ); INSERT INTO tableName (name) VALUES (‘val1’), ('val2'), ('val3'), ('val4'); SELECT * FROM tableName;Output+----+---------+ | id | name | +----+---------+ | 1  | val1 | | 2  | val2 | | 3  | val3 | | ... Read More

Let us understand how to form the query to find the number of web visits per day, per month, per year, and the total in MySQL:Note: We assume we have created a database named ‘DBNAME’ and a table named ‘tableName’.Let us see the MySQL query which can be used to get the web visits per day, month, year and totals −QuerySELECT COUNT(DISTINCT ip) FROM tableName WHERE create_at >= LAST_DAY(NOW()) + INTERVAL 1 DAY - INTERVAL 1 MONTH AND create_at < LAST_DAY(NOW()) + INTERVAL 1 DAYThe above query searches through a range of DATETIME values by beginning from the present month ... Read More

Note: We assume we have created a database named ‘DBNAME’ and a table named ‘tableName’.Let us understand how the count of visitors per day per page can be queried using MySQL. This can be done using the bit group function −QuerySELECT DATE(date) Date, page_id, COUNT(*) colName FROM tableName GROUP BY DATE(date), page_idHere ‘colName’ refers to the ‘visits per day’ column, and ‘tableName’ refers to the table that contains details about visitors.It makes sure that the duplicate values in the table are removed when the above query is run.