The Most Used Concepts : Relational Data Model and Set Theory.
The Relational Database Model Edgar (EF) Codd was the Develop. In the 1960s Dr. Codd Existing Data Models were working on. Based on his experience, he found that all the Data Models were prevalent at that time, they are all quite complicated and unnatural ways to Data Model used.
In Mathematical Set Theory Rows (Tuple) and Columns (Attributes) made Define a Table is used as a Relation. In other words, we can say in Relation Table. The Definition Specify that the only thing to do in a Table Column Store will be all, but it is not Specify the Actual Data. Data in the Table Rows Include as we do, then we receive the Relation an Instance. For example, we may Represent follows in Relation to Student:
At first glance, these Relation Rectangular Portion of a Flat File or Spreadsheet looks like. But when we Relation Table based on Set Theory as to see some very Specific Characteristics in Relation to us then appear. Set Theory Based on watching all of the Relation of Constraints Represent Column DBMS has to be in the Store.
When we Relation of Set Theory Based on the Characteristics of a Column view, then we have a Column Characteristics of the following:
Unique is the name of every Column in a Table.
Store the value of the Column is always only one Domain. Store the value of the Type Table, Column A which is used to define the Column Store only has value. For example, in the Student Table Student Store's name on the Way to Define Column is only for Store Use the Column names can be used only while the Define Column Roll Number Store which has been, it may be the Roll Number Store only.
I.e. one in every Column Store can only assume certain Domain. Column Homogeneous Relations is said to result. Column some or the entire Table is Associated with Domain Constraint. Based on our DBMS Simple Domain Constraint Data Type would like, such as Integers, Characters, and Date etc. like any of Rows Columns in Relation Special Properties or Characteristics are few. These Characteristics are as follows:
In a Row various Column Store we can just only one value. Each of a Row or Column Single-Valued happens. And
Record Unique every one is a Relation. Duplication in Relation it cannot be again in a Row. Relation to Each Unique Record of the DBMS itself does not enforce the Unique Constraint with each ROW, but this feature we receive by Primary Key.
Combination of Columns in a Table or Column Primary Key is a field that Table or Relation to Uniquely Identify a Record or Row Define carried out. As soon as someone in Relation Unique Primary Key Set with Combination of a specific Column or Columns is just what is certain is that each of the Table or Row Unique Record will.
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