In the Entity-Relationship (ER) model, after you have identified the entity types and their properties, you must determine the types of values that these properties can have. In C/SIDE, this corresponds to determining the data types of the fields in your tables.


In this example, your analysis using the ER model has revealed that you have an entity type describing your company's customers. You define the following Customer table.

Company Name Contact Person Phone Payment Method











Your analysis shows that you need fields such as Company Name, Contact Person, Phone, and Payment Method. When you create the Customer table, you select the following data types.

Field name Description Data type

Company Name

The name of the customer (for example, "CRONUS International Ltd.").


Contact Person

The contact person in the company (for example, "JLJ").



The customer's phone number (for example, "45662111").


Payment Method

The payment method for the customer (for example, "pay in cash").


For more information about the available data types, see Field Data Types.