如何添加约束以检查同一个表中的另一列中是否存在值？

Question

I have an entity like this,

@Entity
@Table(name = "Persons", schema="PU")
public class Persons {
  @Basic
  @Column(name = "PERSON_ID")
  private String personId

  @Basic
  @Column(name = "PERSON_NAME")
  private String personName

  @Basic
  @Column(name = "PERSON_NAME_COPY")
  private String personNameCopy
}

I want to add a constraint in the personNameCopy column such that whatever value is being inserted in that column should be present in the personName column.

Is there any way to achieve this?

Answer 1

DROP TABLE IF EXISTS dbo.Person;
CREATE TABLE dbo.Person
(
  PERSON_ID INT NOT NULL PRIMARY KEY,
  PERSON_NAME VARCHAR(50)NOT NULL,
  PERSON_NAME_COPY VARCHAR(50)NOT NULL,
    CONSTRAINT CHK_PERSON_NAME_PERSON_NAME_COPY CHECK (PERSON_NAME=PERSON_NAME_COPY)
)
GO

INSERT dbo.Person(PERSON_ID,PERSON_NAME,PERSON_NAME_COPY)
   VALUES(1,'KUMAR','KUMAR')

--THIS ROW IS TO BE REJECTED
 INSERT dbo.Person(PERSON_ID,PERSON_NAME,PERSON_NAME_COPY)
    VALUES(2,'JOHN','KUMAR')

SELECT *FROM DBO.Person;

if I understand your question correctly you can implement check constraint (example is above) Please also have look https://learn.microsoft.com/en-us/sql/relational-databases/tables/create-check-constraints?view=sql-server-ver16