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In MySQL, the ENUM data type allows you to create a column with specified values like 'A', 'B', 'C', and 'D'. This feature is useful for maintaining data consistency, as it restricts entry to a specific set of values. However, the behavior of ENUM columns can vary depending on whether the NOT NULL constraints are applied and also depends on SQL modes. How to handle ENUM values with SQL modes MySQL accepts empty values for enumeration only if SQL mode is not set as TRADITIONAL, STRICT_TRANS_TABLES, or, STRICT_ALL_TABLES. Otherwise, MySQL would not accept empty values and throw an error. ... Read More
In SQL, joining tables is an essential operation that combines data from multiple sources. While joining two tables is straightforward many real-world scenarios require joining three or more tables to retrieve comprehensive information. This article explains how to join three or more tables, complete with examples. Understanding Joins SQL joins are used to combine rows from two or more tables based on a related column. The Common types of joins include: INNER JOIN: Returns records that have matching values in both tables. ... Read More
Namespaces help in organizing code, managing the scope of variables and preventing naming conflicts. Python and C++ use namespaces, but they do so in different ways. Below is an overview of namespaces in both. Namespaces in C++ In C++, namespaces are created using the keyword 'namespace'. They are mainly intended to organize code into logical groups and avoid name conflicts, particularly when working with multiple libraries. Example In the following example we are going to how to use a namespace by utilizing '::' to access functions within that namespace. #include using namespace std; // first namespace namespace first_space ... Read More
In MySQL, triggers are a mechanism that allow for specific actions to be executed automatically when specific events like Insert, Update, or Delete occur in a table. They are useful as they automate processes and maintain data integrity. Using BEGIN...END in trigger In a trigger, if we want to perform more than one action we write it within the BEGIN…END block. This block simplifies the way we can manage a larger number of actions for a more complicated task. Let us see how the BEGIN...END construct allows multiple statements to be executed within a trigger. We can group ... Read More
Triggers are automatic operations that MySQL performs when something happens in a table, like adding a new record (INSERT), changing a record (UPDATE), or getting rid of a record (DELETE). They come in handy because they can handle repetitive tasks and make sure the info in your database is consistent and accurate without any manual interference. Listing All Triggers in MySQL To list all the triggers in MYSQL we use information_schema.triggers table. This table stores the metadata, which means the details like the trigger name, the action it responds to (INSERT, UPDATE, DELETE), and the table it is associated with. ... Read More
Triggers are a great feature in MySQL that allows the automation of processes either before or after data has changed in a table. An important application of the usage of triggers is for automatic date addition to the database. This article guides you on how to add the current date in MySQL using triggers every time a new record is being inserted. The following examples uses a BEFORE INSERT trigger in setting a date within a column of a table automatically. BEFORE INSERT trigger This trigger is executed right before a value is inserted into a database table. Whenever ... Read More
When we want to add a pause in MySQL triggers or stored procedures, we use the SLEEP() function. This function stops the execution of a query or procedure for a set amount of time. It is useful in different scenarios such as checking how an app acts when operations slow down or stimulating network slowness. SLEEP() Function MySQL has this SLEEP() function that will suspend the operation for a specified time duration. For example, if you want to pause for 5 seconds, you would write - SLEEP(5); This causes the database to wait for 5 ... Read More
HTML Tag To set a smaller font size in an HTML document, use the tag. This tag decreases the font size by one level, from medium to small or extra-large to large. There are two ways to use the tag in HTML. The tag also supports the global attributes and event attributes in HTML. This tag is not deprecated, but it is possible to achieve better results or nearly the same effect with CSS. The tag supports both Event Attributes and Global Attributes in HTML. Although not deprecated, similar or better results can be achieved ... Read More
Linked List Representation Linked lists use dynamic memory allocation, allowing them to grow and shrink as needed. They are defined as a collection of nodes, each containing two parts: data and a link. A linked list is a linear data structure where each element is known as a node, is connected to the next one using pointers. Unlike arrays, elements of a linked list are stored in random memory locations. The representation of data, links, and linked lists is shown below − Representation of node - Representation of Linked List - Insertion Insertion operations in a linked list ... Read More
To hide a div in JavaScript on button click we will be discussing three different approaches with example codes. We will hide the div upon clicking the button and similarly display the hidden div upon clicking the button. In this article we are having a div element. Our task is to hide the div on clicking the button using JavaScript. Approaches to Hide div on Button Click Here is a list of approaches to hide a div in JavaScript on button click which we will be discussing in this article with stepwise explanation and complete example codes. ... Read More