D365 CRM Basics - Understanding field types and their data types

Lets start with a basic concept of Dynamics CRM today, what are the different field types and field data types available and their basic definitions. To start with any field in dynamics falls under the below 3 categories(Except few OOB fields)

What are the types of fields/attributes I can create in D365 CRM?

1. Simple field - Traditional field
2. Calculated field - Based on formula and calculated on the go based on field in current record or related(lookup)
3. Rollup field - Based on formula but used for aggregation from related records

Their handy definition from MS docs is as follows and the applicable field types types is as follow,

Field type	Description	Available field data type
Simple field	Contains data that is not based on a formula.	Single Line of Text, Option Set, Two Options, Image, Whole Number, Floating Point Number, Decimal Number, Currency, Multiple Lines of Text, Date and Time, Lookup
Calculated field	Contains calculations that use fields from the current entity or related parent entities.	Single Line of Text, Option Set, Two Options, Whole Number, Decimal Number, Currency, Date and Time
Rollup field	Contains an aggregate value computed from the records related to a record, or a value computed over a hierarchy.	Whole Number, Decimal Number, Currency, Date and Time

What are the different data types available to configure?

D365 CRM supports wide range of data types and its better to understand all the available datatypes before settling down with one. If a field is created under certain data type, then field is locked for further data type swaps. Be wise before choosing one, else we may need to delete and recreate a field.

The field data types and their handy definitions from MS docs is as follows

Field data type	Description
Single Line of Text	This field can contain up to 4,000 text characters. You can set the maximum length to be less than this. This field has several format options that will change the presentation of the text. These options are Email, Text, Text Area, URL, Ticker Symbol, and Phone. More information: More information: Single line of text format options
Multiple Lines of Text	This field can contain up to 1,048,576 text characters. You can set the maximum length to be less than this. When you add this field to a form, you can specify the size of the field.
Option Set	This field provides a set of options. Each option has a number value and label. When added to a form, this field displays a control for users to select only one option. When this field is displayed in Advanced Find, users can use a picklist control to select multiple options to include in their search criteria. You can define a single, global option set and configure MultiSelect Option Set fields to use that single set of options. More information: More information: Creating and editing global option sets
MultiSelect Option Set	This field provides a set of options, where multiple options can be selected. When added to a form, this field uses a control for users to select multiple options. When this field is displayed in Advanced Find, users can select multiple options from the list to include in their search criteria. You can define a single global option set and configure MultiSelect Option Set fields to use that single set of options. More information: More information: Creating and editing global option sets
Two Options	This field provides two options. Each option has a number value of 0 or 1 corresponding to a false or true value. Each option also has a label so that true or false values can be represented as “Yes” and “No”, “Hot” and “Cold”, “On” and “Off” or any pair of labels you want to display. Two option fields don’t provide format options at the field level. But when you add one to the form you can choose to display them as radio buttons, a check box, or a select list.
Status	A system field that has options that generally correspond to active and inactive status. Some system attributes have additional options, but all custom attributes have only Active and Inactive status options. You can also include custom state transitions to control which status options are available for certain entities. More information: Define status reason transitions
Status Reason	A system field that has options that provide additional detail about the Status field. Each option is associated with one of the available Status options. You can add and edit the options.
Whole Number	Integers with a value between -2,147,483,648 and 2,147,483,647 can be in this field. You can restrict the maximum or minimum values in this range. This field has format options None, Duration, Time Zone, and Language that change depending on how the field is presented. More information: Whole number format options
Floating Point Number	Up to 5 decimal points of precision can be used for values between -100,000,000,000 and -100,000,000,000 can be in this field. You can specify the level of precision and the maximum and minimum values. More information: Using the right type of number
Decimal Number	Up to 10 decimal points of precision can be used for values between -100,000,000,000 and -100,000,000,000 can be in this field. You can specify the level of precision and the maximum and minimum values. More information: Using the right type of number
Currency	Monetary values between -922,337,203,685,477 and 922,337,203,685,477 can be in this field. You can set a level of precision or choose to base the precision on a specific currency or a single standard precision used by the organization. More information: Using Currency Fields
Date and Time	This field has format options to display Date Only or Date and Time.
Image	Each entity that supports images can have one image field. When an entity has an image field, it can be configured to display the image for the record in the application. More information: Image fields, Video: Dynamics CRM Image Data Type
Lookup	A field that allows setting a reference to a single record of a specific type of entity. Some system lookup fields behave differently. More information: Different types of lookups
Owner	A system lookup field that references the user or team that is assigned a user or team owned entity record.
Unique Identifier	A system field stores a globally unique identifier (GUID) value for each record.
Customer	A lookup field that you can use to specify a customer, which can be an account or contact.

Reference: https://docs.microsoft.com/en-us/dynamics365/customer-engagement/customize/types-of-fields