Domain integrity is concretely related only with proper data. Ex. we have data type like integer, varchar, char, smallint, bigint etc and what data inserted in this. Is this belonging to the same datatype of that column. Bascially it is just a concept in integrity of data. but some where we have to take care of data like "Email" . As an example, if frontend made in HTML with of ots own and backend as MySql. After collecting email data from email textbox, first it validated from the fronted and then again validated from backend. So , here we have see weather we email data or something else in the text box. Finally, just focus on data that is stored in respective column with respective data types. So we just have to taking care of data stored in table. Hope this is helpful. if any discrepancy , kindly correct it.
It enforces valid entries for a given column by restricting the type, the format, or the range of values.
Domain integrity specifies that all columns in a relational database must be declared upon a defined domain. The primary unit of data in the relational data model is the data item. Such data items are said to be non-decomposable or atomic. A domain is a set of values of the same type.
Each attribute in the model should be assigned domain information which includes:
Data Type - Basic data types are integer, decimal, or character. Most data bases support variants of these plus special data types for date and time.Length - This is the number of digits or characters in the value. For example, a value of 5 digits or 40 characters.Date Format - The format for date values such as dd/mm/yy or mm/dd/yyyy or yy/mm/dd.Range - The range specifies the lower and upper boundaries of the values the attribute may legally have.Constraints - Are special restrictions on allowable values. For example, the LeavingDate for an Employee must always be greater than the HireDate for that Employee.Null support - Indicates whether the attribute can have null values.Default value (if any) - The value an attribute instance will have if a value is not entered.