An entity is an object or component of data. An entity is represented as rectangle in an ER diagram. For example: In the following ER diagram we have two entities Student and College and these two entities have many to one relationship as many students study in a single college.
Entity Relationship Model (ER Modeling) is a graphical approach to database design. It is a high-level data model that defines data elements and their relationship for a specified software system. An ER model is used to represent real-world objects. For example, each employee of an organization is a separate entity.
In a relational database, a weak entity is an entity that cannot be uniquely identified by its attributes alone; therefore, it must use a foreign key in conjunction with its attributes to create a primary key. The foreign key is typically a primary key of an entity it is related to.
1a : being, existence especially : independent, separate, or self-contained existence. b : the existence of a thing as contrasted with its attributes. 2 : something that has separate and distinct existence and objective or conceptual reality.
The Entity Relationship Diagram (ERD) is a graphical representation of an ERM and is currently one of the most popular and widely used database design tools. The three main components of the ER Model are entities, attributes and relationships.
ER Diagram: Weak EntityWeak entity is an entity that depends on another entity. Weak entity doesn't have anay key attribute of its own. Double rectangle is used to represent a weak entity.
Database entity is a thing, person, place, unit, object or any item about which the data should be captured and stored in the form of properties, workflow and tables. While workflow and tables are optional for database entity, properties are required (because entity without properties is not an entity).
In the Field List, in “Relationships between tables may be needed”, click Create. In Related Table, select On_Time_Performance and in Related Column (Primary) choose FlightDate. In Table, select BasicCalendarUS and in Column (Foreign) choose DateKey. Click OK to create the relationship.
Excel Precedents Keyboard ShortcutsThere are specific keyboard shortcuts that can be used to track how formulas are linked within an Excel model. The shortcuts include: Trace Precedents: Press “Ctrl” followed by the square bracket “[“. The shortcut takes you to the first cell used by the active cell with the formula.
Pivot tables are one of Excel's most powerful features. A pivot table allows you to extract the significance from a large, detailed data set. Our data set consists of 213 records and 6 fields. Order ID, Product, Category, Amount, Date and Country.
Create New Relationships between the Stores and Sales
- Click the dbo_FactSales tab.
- Select the StoreId column.
- On the Design tab, click Create Relationship.
- The Table field and the Column field are auto-populated.
- In the Related Lookup Table field, select Stores.
- In the Related Lookup Column field, select StoreKey.
Create a table relationship by using the Relationships window
- On the Database Tools tab, in the Relationships group, click Relationships.
- On the Design tab, in the Relationships group, click Add Tables (or Show Table in Access 2013).
- Select one or more tables or queries and then click Add.
Excel file formats
| Format | Extension |
|---|
| Excel Workbook | .xlsx |
| Excel Macro-Enabled Workbook (code) | .xlsm |
| Excel Binary Workbook | .xlsb |
| Template | .xltx |
Open the Power Pivot window, select the Design tab, and then select the Manage Relationships command. In the Manage Relationships dialog box, shown here, click the relationship you want to work with and click Edit or Delete. Use the Manage Relationships dialog box to edit or delete existing relationships.
Here's how to find them.
- Select a cell, or a range of cells. If you select one cell, you search the whole worksheet. If you select a range, you search just that range.
- Click Home > Find & Select > Go To Special.
- Click Formulas, and if you need to, clear any of the check boxes below Formulas.
Select Insert, Shapes dropdown and choose an arrow.
- Shapes are in single menu now. Click in the origin cell and drag to the final cell.
- This is a curve with an arrow added later.
- The black handles show the mouse click locations.
- Edit the points of the curve.
Click Power Pivot > Add to Data Model. Click Insert > PivotTable, and then check Add this data to the Data Model in the Create PivotTable dialog box.
A Data Model integrates the tables, enabling extensive analysis using PivotTables, Power Pivot, and Power View. A Data Model is created automatically when you import two or more tables simultaneously from a database. The existing database relationships between those tables is used to create the Data Model in Excel.
How to create a customer database in Excel:
- Enter the name of the database field (column headings).
- Enter data into the database. We are keeping order in the format of the cells.
- To use the database turn to tools «DATA».
- Assign the name of the database. Select the range of data - from the first to the last cell.
Start the Power Pivot add-in for Excel
- Go to File > Options > Add-Ins.
- In the Manage box, click COM Add-ins> Go.
- Check the Microsoft Office Power Pivot box, and then click OK. If you have other versions of the Power Pivot add-in installed, those versions are also listed in the COM Add-ins list. Be sure to select the Power Pivot add-in for Excel.
First, import your dataset into your Power Pivot workbook. Next, in the Power Pivot window on the Power Pivot Home tab, click PivotTable. Next, select “New Worksheet” (Excel will add an empty PivotTable). Then, select the empty PivotTable and follow the instructions detailed there.
To show a linear relationship using Excel, such as density, complete the following steps:
- Enter the X values in column A.
- Enter the Y values in column B.
- Press the chart button in the toolbar, OR under Insert in the menu, select Chart.
- Select plot type "XY scatter".
- Set the data range by selecting all the data.
A relationship chart is a visual representation of a person's ancestry. It provides vital clues to identify the relationship between relatives. Hence, you may want to create a relationship family diagram to preserve your family history for generations to come.
On the Ribbon, under the PivotTable Tools tab, click the Analyze tab (in Excel 2010, click the Options tab). In the Data group, click the top section of the Change Data Source command. The Change PivotTable Data Source dialog box opens, and you can see the the source table or range in the Table/Range box.
A PivotTable is an interactive way to quickly summarize large amounts of data. You can use a PivotTable to analyze numerical data in detail, and answer unanticipated questions about your data. A PivotTable is especially designed for: Querying large amounts of data in many user-friendly ways.
There are many
different forms of
modeling.
Below are the 10 main types of modeling
- Fashion (Editorial) Model. These models are the faces you see in high fashion magazines such as Vogue and Elle.
- Runway Model.
- Swimsuit & Lingerie Model.
- Commercial Model.
- Fitness Model.
- Parts Model.
- Fit Model.
- Promotional Model.
How to Draw an Entity Relationship Diagram
- Determine the Entities in Your ERD. Start by identifying the “what”s in your system or architecture.
- Add Attributes to Each Entity. Next, consider the attributes that you need to describe each entity.
- Define the Relationships Between Entities.
- Add Cardinality to Every Relationship.
- Finish and Save Your ERD.
How To Draw NoSql Data Model Diagram?
- Example Problem Statement. Let us take a problem statement and draw our data model diagram around it in steps:
- Product.
- Cashier.
- Product Has Many Items.
- Transaction.
- Transaction Belongs To Product, Cashier And Item.
- Rounding Out.
- A More Complex Design Example.
Primary Key is one of its attributes which helps to identify its member. In a weak entity set, it is a combination of primary key and partial key of the strong entity set. In the ER diagram the relationship between two strong entity set shown by using a diamond symbol.
Just right click on diagram pane and choose Add Table. This will create a diagram with the tables columns, primary keys, and relationships that were read from the schema.
A model uses UML or other notation to describe a system at various levels of abstraction. Models often contain one or more diagrams that display an aspect of a model or a subset of the model's elements graphically. In this way, a diagram represents a certain aspect or part of a model.
Sequence diagrams are sometimes called event diagrams or event scenarios. A sequence diagram shows, as parallel vertical lines (lifelines), different processes or objects that live simultaneously, and, as horizontal arrows, the messages exchanged between them, in the order in which they occur.
In a one-to-many relationship, one record in a table can be associated with one or more records in another table. For example, each customer can have many sales orders. The foreign key field in the Orders table, Customer ID, is designed to allow multiple instances of the same value.
