Data truncation exception while joining one to one in JPA

What went wrong? When I looked at generated table the filed type for classid was LOB while I expected it to be an int (It just an ID from foreign key). The culprit is -using column instead of joincolumn

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public class StudentDetails implements Serializable{     @OneToOne(cascade={CascadeType.REFRESH,CascadeType.MERGE},fetch = FetchType.EAGER)     @Column(name="classid")      private ClassDetails classId;   Instead of column, it should be join column       @OneToOne(cascade={CascadeType.REFRESH,CascadeType.MERGE},fetch = FetchType.EAGER)     @JoinColumn(name="classid",nullable=false) <strong> See the joincolumn </strong>     private ClassDetails classId;}

If join column is not specified, JPA assumes that ClassDetails object will be saved (along with its all nested graph) to DB and hence it creates a LOB type -telling it that its a joined foreign key resulted in a int data type for the field.

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