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Unable to create many-to-one mapping

subhashchandra medhiassam
Ranch Hand

Joined: Sep 10, 2008
Posts: 72
Dear friends,
I am using JDBC to create two tables in MYSQL and then insert data into these two tables. The tables are named as Publisher and Book. For each row in table Publisher there could be multiple rows in table Book.

The code looks like the folowing:

PreparedStatement pstmt1 = null;
PreparedStatement pstmt2 = null;
PreparedStatement pstmt3 = null;
PreparedStatement pstmt4 = null;

try{
Class.forName("com.mysql.jdbc.Driver").newInstance();
}catch(Exception e){
System.out.println(e.getMessage());
}
try{
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost/hibernatetutorial?" +
"user=root&password=root");

pstmt1 = conn.prepareStatement("CREATE Table Publisher(ID bigint(20) primary key,CODE varchar(4),PUBLISHER_NAME varchar(100),ADDRESS varchar(200))");
boolean check1 = pstmt1.execute();

pstmt2 = conn.prepareStatement("CREATE Table Book(ID bigint(20),ISBN varchar(50),BOOK_NAME varchar(100),PUBLISH_DATE date,PRICE int(11),PUBLISHER_ID bigint(20),foreign key(PUBLISHER_ID) REFERENCES Publisher(ID))");
boolean check2 = pstmt2.execute();

pstmt3 = conn.prepareStatement("INSERT INTO Publisher values(?,?,?,?)");
pstmt3.setLong(1,(long)1);
pstmt3.setString(2,"adfs");
pstmt3.setString(3,"zfkljfj dalldl");
pstmt3.setString(4,"100 skhdkhke,sojol,lskjs");
boolean check3 = pstmt3.execute();

pstmt4 = conn.prepareStatement("INSERT INTO Book values(?,?,?,?,?,?)");

Date date = Date.valueOf("03-10-2008");
pstmt4.setLong(1,(long)1);
pstmt4.setString(2,"abcdef");
pstmt4.setString(3,"xyz");
pstmt4.setDate(4,date);
pstmt4.setInt(5,100);
pstmt4.setLong(6,(long)5);
boolean check4 = pstmt4.execute();


When i execute this program,however, i am getting the following message:

Duplicate key or integrity constraint violation message from server: "Cannot add or update a child row: a foreign key constraint fails (`hibernatetutorial/book`, CONSTRAINT `book_ibfk_1` FOREIGN KEY (`PUBLISHER_ID`) REFERENCES `publisher` (`ID`))"

What could have gone wrong ? Kindly help.

Thanks,
Subhash
Brij Garg
Ranch Hand

Joined: Apr 29, 2008
Posts: 234
PUBLISHER_ID in Book is a foreign key to ID of Publisher.
Any record you are inserting in Book should have corresponding record in Publisher.

In your case:-
publisher_id value is 5 but there is no record in Publisher table with ID having value 5.

I think this is the reason for this error.
subhashchandra medhiassam
Ranch Hand

Joined: Sep 10, 2008
Posts: 72
Okay, thanks Bittoo. I changed 5 to 1 and it's working now.
Adeel Ansari
Ranch Hand

Joined: Aug 15, 2004
Posts: 2874
Bittoo doesn't sound like your genuine name, its more like a nick or fictitious name.
 
 
subject: Unable to create many-to-one mapping
 
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