@mustufam5967803 ,
There could be several reasons why this may occur:
- Schema Design: The schema design may allow for empty or null values in the primary key column. For example, the primary key column may not have been defined with a NOT NULL constraint, or it may have been designed to allow null values.
- Database Management System (DBMS) Settings: The settings of the specific DBMS being used may allow for empty or null values in the primary key column. For example, some DBMS allow for null values in primary key columns by default, or there may be a specific configuration or setting that allows for this behavior.
- Data Loading Process: The data loading process used to insert data into the table may not be enforcing the primary key constraint properly. For example, the data loading process may not be validating or checking for empty or null values in the primary key column before inserting the data into the table.
It is important to review the schema design, DBMS settings, and the data loading process to determine why empty values are being allowed in the primary key column.