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Identifying entity relationships in DBMS is used to identify a relationship between strong and weak entity.Before beginning, let us take an example of Professor entity, which is our Strong Entity, with Professor_ID as a Primary Key −Professor_IDProfessor_NameProfessor_CityProfessor_SalaryThe weak entity is Professor_Dependents entity:NameDOBRelationNow, let us continue, Weak EntityWeak Entity is dependent on Strong Entity and does not have a primary key. Weak Entity has a partial key. It is represented as double rectangle −Strong EntityOther entities are dependent on Strong Entity and it has a key attribute i.e. a primary key and represented as a single rectangle.Identifying RelationshipsIt links the strong and weak entity ... Read More
The HTML DOM Input Email required property determines whether Input Email is compulsory to set or not.SyntaxFollowing is the syntax −Returning boolean value - true/falseinputEmailObject.requiredSetting required to booleanValueinputEmailObject.required = booleanValueBoolean valuesHere, “booleanValue” can be the following −booleanValueDetailstrueIt is compulsory to set the email field to submit form.falseIt is the default value and to set an email field is not compulsory.ExampleLet us see an example of Input Email required property − Live Demo Input Email required form { width:70%; margin: 0 auto; text-align: center; } * { ... Read More
Managing data was the key and was essential. Therefore, data model originated to solve the file system issues. Here are the Data Models in DBMS −Hierarchical ModelIn Hierarchical Model, a hierarchical relation is formed by collection of relations and forms a tree-like structure.The relationship can be defined in the form of parent child type.One of the first and most popular Hierarchical Model is Information Management System (IMS), developed by IBM.ExampleThe hierarchy shows an Employee can be an Intern, on Contract or Full- Time. Sub-levels show that Full-Time Employee can be hired as a Writer, Senior Writer or Editor:AdvantagesThe design of ... Read More
DFS visits the child vertices before visiting the sibling vertices; that is, it traverses the depth of any particular path before exploring its breadth. A stack (often the program's call stack via recursion) is generally used when implementing the algorithm.Following is how a DFS works −Visit the adjacent unvisited vertex. Mark it as visited. Display it. Push it in a stack.If no adjacent vertex is found, pop up a vertex from the stack. (It will pop up all the vertices from the stack, which do not have adjacent vertices.)Repeat Rule 1 and Rule 2 until the stack is empty.Let us ... Read More
A topological sort or topological ordering of a directed graph is a linear ordering of its vertices such that for every directed edge UV from vertex u to vertex v, u comes before v in the ordering. This only makes sense in directed graphs.There are many places where topological sort makes a lot of sense. For example, let's say you're following a recipe, in this, there are some steps that are must for going to the next steps. But some of these can be performed in parallel. In a similar fashion, during college when selecting courses, there are some prerequisites ... Read More
for…in loopThe “for...in” loop is used to loop through an object's properties.Here’s the syntax −Syntaxfor (variablename in object) { statement or block to execute }You can try to run the following example to implement ‘for-in’ loop. It prints the web browser’s Navigator objectExampleLive Demo var aProperty; document.write("Navigator Object Properties "); for (aProperty in navigator) { document.write(aProperty); document.write(""); } document.write ("Exiting from the loop!"); for…of loopThe “for…of” loop is used to loop through iterable objects, which includes Map, Array, arguments, etc.SyntaxHere’s the syntax −for (variablename of iterable){ statement or block to execute }ExampleHere’s an example showing ... Read More
In graph theory, the shortest path problem is the problem of finding a path between two vertices (or nodes) in a graph such that the sum of the weights of its constituent edges is minimized. Here we need to modify our add edge and add directed methods to allow adding weights to the edges as well. Let us look at how we can add this −Example/** * Adds 2 edges with the same weight in either direction * * weight * node1 node2 * ... Read More
The HTML DOM Input Datetime name property returns a string, which is the value of the name attribute of input datetime. User can also set it to a new string.SyntaxFollowing is the syntax −Returning string valueinputDatetimeObject.nameSetting name attribute to a string valueinputDatetimeObject.name = ‘String’ExampleLet us see an example of Input Datetime name property − Live Demo Input Datetime Name Datetime: Change name value var inputDatetime = document.getElementById("datetime"); var divDisplay = document.getElementById("divDisplay"); divDisplay.textContent = 'Name of datetime input: '+inputDatetime.name; function changeNameValue() { if(inputDatetime.name == "Mother's Birth ... Read More
The lifetime of a JavaScript variable begins when it is declared −var rank;A local variable will be visible only within a function where it is defined. Function parameters are always local to that function.The completion of a function deletes the local variable.A global variable has a global scope which means it can be defined anywhere in your JavaScript code. Global variables delete when the web browser is closed. However if a new page is loaded in the same browser window, then it remains.Here’s the usage of global variables −ExampleYou can try to run the following code to learn how to ... Read More
Dijkstra's algorithm is an algorithm for finding the shortest paths between nodes in a weighted graph. We'll use the new addEdge and addDirectedEdge methods to add weights to the edges when creating a graph. Let us look at how this algorithm works −Create a distance collection and set all vertices distances as infinity except the source node.Enqueue the source node in a min-priority queue with priority 0 as the distance is 0.Start a loop till the priority queue is empty and dequeue the node with the minimum distance from it.Update the distances of the connected nodes to the popped node ... Read More