for this field because many employees may not have phone numbers. SuperId : This column in the Employee table structure refers to EmpId of the supervisor or immediate superior of the employee. Its data type is set to Text with field width , the same as is for EmpId. Its Required property is set to No with Allow Zero Length property being Yes to imply that null values are also permitted.
This is because the overall boss of the organisation, although an employee, does not have any boss and therefore a null value in this field is to be allowed to accommodate the situation. (d) Vouchers : This table has been designed to store the transaction data as contained in a voucher. It has nine columns, the details of each are given below : Vno : This column is meant to store voucher number, which indicates the distinct identity of a transaction. Its data type could be number if numeric digits are assigned to each of the vouchers.
However, its data type is normally taken as text because it is amenable to any type of numbering, coding or ordering scheme: numeric, alpha-numeric or formatted reference. Its width may be set to so that first places to the left refer to numeric month of the date and next places to numeric digits giving identity to each of the transactions that have occurred during the month under reference. This column is designed to have distinct values and therefore can be designated as primary key of the table. Accordingly, its value cannot be null and therefore its Allow Zero Length property must be set to No with Required property being Yes .
However, its data type needs be taken as number (with Integer), when numeric function(s) such as Dmax() is applied to find maximum values for auto-generating the vouchers. Debit : This column is meant to store the code corresponding to an account, which has been debited in recording a transaction. Since it references the code column, which is the primary key of Accounts table as described above, it