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.

Let us first see what is Composite Index −A composite index is an index that is used on multiple columns.It is also known as a multiple-column index.MySQL allows the user to create a composite index which can consist of up to 16 columns.The query optimizer uses the composite indexes for queries which will test all columns in the index.It can also be used for queries which will test the first columns, the first two columns, and so on.If the columns are specified in the right order in the index definition, a single composite index can be used that would speed ... Read More

A composite index is an index that is used on multiple columns. It is also known as a multiplecolumn index.FeaturesLet us see the features −MySQL allows the user to create a composite index which can consist of up to 16 columns.The query optimizer uses the composite indexes for queries which will test all columns in the index.It can also be used for queries which will test the first columns, the first two columns, and so on.If the columns are specified in the right order in the index definition, a single composite index can be used that would speed up certain ... Read More

Let us understand how to search multiple columns in MySQL −Note: We assume we have created a database named ‘DBNAME’ and a table named ‘tableName’.The ‘AND’ and ‘OR’ operators can be used, depending on what the user wants the search to return.Let us see that with the help of an example −ExampleSELECT colName FROM tableName WHERE my_col LIKE %$param1% AND another_col LIKE %$param2%;In the above example, the ‘AND’ operator is used.This means that both the clause has to match a record for the result to be returned.QuerySELECT colName FROM tableName WHERE my_col LIKE %$param1% OR another_col LIKE %$param2%;In the above ... Read More