We Keep Coding

Unnecessary Foreign Key Constraint Failure

So I have a mock database for a conference where I'm creating tables for the authors, papers, reviewers, etc.
The reviewers provide an email which refers to the Program Committee emails. This is the key constraint I put in place. Then I add data to the PC table and then attempt to add data to the reviewer table. This is the error I get:
Exception encountered com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Cannot add or update a child row: a foreign key constraint fails (`sampledb`.`review`, CONSTRAINT `review_ibfk_2` FOREIGN KEY (`email`) REFERENCES `pcmember` (`email`))
Here are the other functions:
public int loadPCMember(){
String tablename = "pcmember";
String create = "CREATE TABLE IF NOT EXISTS pcmember(email VARCHAR(100), name VARCHAR(50), PRIMARY KEY (email));";
makeTable(create);
System.out.println("made table pcmember");
//CSV Reader
String[][] content = CSVReader(tablename,2);
for(int i = 0 ; i < content.length; i++){
try{
String query = "INSERT INTO pcmember(email,name) VALUES (?,?)";
PreparedStatement ps2 = net.prepareStatement(query);
ps2.setString(1, content[i][0]);
ps2.setString(2, content[i][1]);
ps2.executeUpdate();
System.out.println((i+1)+ " done");
// Throw exception
}catch (SQLException e){System.out.println("Exception encountered");return 0;}
}
System.out.println("PC Member Done");
return 1;
}
//Load next
public int loadReview(){
String tablename = "review";
String create = "CREATE TABLE IF NOT EXISTS review(reportid INTEGER, sdate DATE, comment VARCHAR(250), recommendation VARCHAR(6), paperid INTEGER NOT NULL, email VARCHAR(100) NOT NULL, PRIMARY KEY(reportid), FOREIGN KEY (paperid) REFERENCES paper(paperid), FOREIGN KEY(email) REFERENCES pcmember(email));";
makeTable(create);
System.out.println("made table review");
//CSV Reader
String[][] content = CSVReader(tablename,6);
for(int i = 0 ; i < content.length; i++){
System.out.println("" + content[i][0] + "\t" +content[i][1] + "\t" + content[i][2] + "\t" +content[i][3] + "\t" +content[i][4] + "\t" +content[i][5]);
try{
//SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yy");
//java.util.Date date = sdf.parse(content[i][1]);
//System.out.println(""+date);
//Date newDate = new Date(date.getTime());
//System.out.println(""+newDate);
String query = "INSERT INTO review(reportid,sdate,comment,recommendation,paperid,email) VALUES (?,?,?,?,?,?)";
PreparedStatement ps2 = net.prepareStatement(query);
ps2.setInt(1, Integer.parseInt(content[i][0]));
ps2.setDate(2, java.sql.Date.valueOf(content[i][1]));
ps2.setString(3, content[i][2]);
ps2.setString(4, content[i][3]);
ps2.setInt(5, Integer.parseInt(content[i][4]));
ps2.setString(6, content[i][5]);
ps2.executeUpdate();
System.out.println((i+1)+ " done");
// Throw exception
}catch (SQLException e){System.out.println("Exception encountered "+ e);return 0;
}//catch (ParseException e){System.out.println("Parse Exception encountered "+e);}
}
System.out.println("Review Done");
return 1;
}
I have a decent understanding of the key constraints and I'm pretty spot on with the CSV files having the same exact emails, so what could be causing this error?

I'm a SQL guy, not a Java guy. If I ask or suggest anything that doesn't make sense because of that - you know why. To be clear - based on that error message and the sql you have included it looks like you trying to insert a record into the review table that has an email address that doesn't exist in the pcmember table thus violating the foreign key constraint on the review table. This seems like a data problem with the CVSs you are using. However since you mentioned that you are confident in the data files is it possible that the it's trying to INSERT the rows into the review table before the pcmember INSERT has successfully completed?

Data insertion using auto incremented column as primary key

I have two tables whereby the primary key(foreign key on the other table) is auto incremented at run time (using TOAD for mysql).
How can I insert data into the two tables at the same time using a transaction.
This is the ddl for the first table:
CREATE TABLE `suspendedsales` (
`SID` int(11) NOT NULL AUTO_INCREMENT,
`SequenceNo` int(11) NOT NULL DEFAULT '0',
`ProductCode` varchar(100) DEFAULT NULL,
`ItemName` varchar(100) DEFAULT NULL,
`Quantity` int(11) DEFAULT NULL,
`Discount` double DEFAULT NULL,
`ItemCost` double DEFAULT NULL,
PRIMARY KEY (`SID`,`SequenceNo`),
CONSTRAINT `SIDFKey` FOREIGN KEY (`SID`) REFERENCES `suspendedsalesdetails` (`SID`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
The ddl for the second table:
CREATE TABLE `suspendedsalesdetails` (
`SID` int(11) NOT NULL DEFAULT '0',
`Date` date DEFAULT NULL,
`Total` double DEFAULT NULL,
PRIMARY KEY (`SID`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
N.B: The major challenge would be to get the auto-incremented key value from on the primary key to be inserted into the other table at run time.
Thanks in anticipation.

If your database is a MySql database you can insert a record in the first table use the following function
SELECT LAST_INSERT_ID();
to get the last inserted id and you can use it in the second insert. Commit all only after the second insert

How about this:
private void insert() {
OraclePreparedStatement statement = null;
try {
Connection dbConnection = getConnection();
statement = dbConnection.createStatement();
String insertToSuspendedsales = "insert into suspendedsales (SequenceNo, ProductCode,ItemName,Quantity,Discount,ItemCost) "
+ "values(:segNo, :prodNo, :itmeName, :quantity, :discount, :itemCost) returning SID into ?";
statement.setIntAtName("segNo", intValue);
....
int id = statement.registerReturnParameter(1, OracleTypes.INTEGER)
statement.executeUpdate(insertToSuspendedsales);
String insertToSuspendedsalesdetails = "insert into suspendedsalesdetails (SID, Date, Total) "
+ "values(:sid, :date, :total) returning SID into ?";
statement.setIntAtName("sid", id);
....
statement.executeUpdate(insertToSuspendedsalesdetails);
} catch (SQLException ex) {
ex.printStackTrace();
//rollback
} finally {
//close Connection
}
}

Preventing from Multiple primary key error

This is my code for executing in my java program:
public static void createBooksTablesAndSetPK() {
String selectDB = "Use lib8";
String createBooksTable = "Create table IF NOT EXISTS books (ID int,Name varchar(20),ISBN varchar(10),Date date )";
String bookTablePK = "ALTER TABLE BOOKS ADD PRIMARY KEY(id)";
Statement st = null;
try (
Connection con = DriverManager.getConnection(dbUrl, "root", "2323");) {
st = con.createStatement();
st.execute(selectDB);
st.execute(createBooksTable);
st.execute(bookTablePK);
} catch (SQLException sqle) {
sqle.printStackTrace();
}
}
I cat use IF NOT EXIST for creating databasesand tables to prevent creating duplicate database and tables and corresponding errors.
But i don't know how prevent Multiple primary key error, because program may call createBooksTablesAndSetPK() multiple times.
Error:
com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Multiple primary key defined

The column Book_id is not existing in your case. You are creating a table with ID as the column and then updating the table with a PRIMARY KEY constraint on a column that is not existing.
Create table IF NOT EXISTS books (ID int,Name varchar(20),ISBN varchar(10),Date date )
ALTER TABLE BOOKS ADD PRIMARY KEY(BOOK_id)
Try running these statements on a MySQL command prompt (or MySql Workbench) and the see the error.
You need change the alter table command like this.
ALTER TABLE BOOKS ADD BOOK_id VARCHAR( 255 ), ADD PRIMARY KEY(BOOK_id);

Compare an SQL file to an existing database table with Java

I am writing a bit of Java (1.7) code to test a given database table against a given sql file. What I would like is a way to turn my sql file into a java object, then test the db field names and field types are the same as the file backed object.
An example sql file looks like this:
create table foo (
id int not null auto_increment,
term_id varchar(128) not null,
term_name varchar(255) not null,
parent_id varchar(128) not null,
parent_name varchar(255),
top_term_flag varchar(5),
primary key (id)
);
create index foo_pn on foo ( parent_name );
create index foo_ttf on foo ( top_term_flag );
And the part of my Java program to do this check looks like this:
// Step 1, confirm the table exists
// Database and table tests
DatabaseMetaData dbm = connection.getMetaData();
// check if "this.dbtable" exists.
// The ToUpperCase covers Oracle
ResultSet tables = dbm.getTables(null, null, this.dbtable.toUpperCase(), null);
if (tables.next()) {
// Table exists
log.info("Table: {} exists!", this.dbtable);
// Step 2, get each field and test against the file
ResultSet columns = dbm.getColumns(null, null, this.dbtable, null);
while ( columns.next()) {
String name = columns.getString(4); // this gets the column name
-> Now what? <-
}
}
I've looked at Spring JDBCTestUnit and Flyway, but they don't seem to provide the functionality I need.
Thank you.
Update:
I understand I can also use Hibernate to generate my Java classes that represent my sql file and then test the DB table against those. Does any one have a sample for how to get this done?

Using JSqlParser 0.8.8 from https://github.com/JSQLParser/JSqlParser.
Here is a parsing example to get column names, table name, types. As a result you get a hierarchy of java objects from your sqls.
public class CheckSQLs {
public static void main(String[] args) throws JSQLParserException {
String sqls = "create table foo (\n"
+ " id int not null auto_increment,\n"
+ " term_id varchar(128) not null,\n"
+ " term_name varchar(255) not null,\n"
+ " parent_id varchar(128) not null,\n"
+ " parent_name varchar(255),\n"
+ " top_term_flag varchar(5),\n"
+ " primary key (id)\n"
+ ");\n"
+ "create index foo_pn on foo( parent_name );\n"
+ "create index foo_ttf on foo ( top_term_flag );";
for (String sql : sqls.split(";")) {
Statement parse = CCJSqlParserUtil.parse(sql);
System.out.println(parse);
if (parse instanceof CreateTable) {
CreateTable ct = (CreateTable)parse;
System.out.println("table=" + ct.getTable().getFullyQualifiedName());
for (ColumnDefinition colDef : ct.getColumnDefinitions()) {
System.out.println("column=" + colDef.getColumnName() + " " + colDef.getColDataType() + " " + colDef.getColumnSpecStrings());
}
}
}
}
}
This runs with the output:
CREATE TABLE foo (id int not null auto_increment, term_id varchar (128) not null, term_name varchar (255) not null, parent_id varchar (128) not null, parent_name varchar (255), top_term_flag varchar (5), primary key (id))
table=foo
column=id int [not, null, auto_increment]
column=term_id varchar (128) [not, null]
column=term_name varchar (255) [not, null]
column=parent_id varchar (128) [not, null]
column=parent_name varchar (255) null
column=top_term_flag varchar (5) null
Now you could use this object to validate against your database.

If the SQL file syntax doesn't vary much from your example, you could write a simple parser to read the file and generate your java object: table plus list of fields/types and indexes
"tablename" always comes after "create table"
the field names and types always come after that
indexes after that
Or there are parsers available:
jsqlparser
http://jsqlparser.sourceforge.net/
Other questions on this site cover some of the same ground
SQL parser library for Java

Update table with primary key and unique columns using Hibernate and mySQL

I have a table containing four columns:
CREATE TABLE `participants` (
`id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
`name` VARCHAR(128) NOT NULL,
`function` VARCHAR(255) NOT NULL,
`contact` VARCHAR(255) NOT NULL,
PRIMARY KEY (`id`),
UNIQUE INDEX `name_function_contact` (`name`, `function`, `contact`)
)
From the application I get participants-objects, which might have values for name, functionand contactwhich are already in that exact matter in the database. In this case I want Hibernate to get me the idof that object, otherwise I want to save the object.
Using saveOrUpdate()I just get an:
org.hibernate.exception.ConstraintViolationException: Duplicate entry 'NAME-FUNCTION-CONTACT: NAME' for key 'name_function_contact'
How can I accomplish this? Thanks a lot!

Since the answers suggested that Hibernate cannot do it on its own (bummer!) I solved it the "native sql" way:
Participants tempParti = ((Participants) session.createQuery("FROM Participants WHERE name = '" + p.getName() + "' AND function = '" + p.getFunction() + "' AND contact = '" + p.getContact() + "'").uniqueResult());
if (tempParti != null) {
p = tempParti;
} else {
session.save(p);
}
Works like a charm! Thanks to all of you!

I am no expert in Hibernate. But from Mysql perspective, you do the following.
use INSERT IGNORE INTO... to add the value in the table. If the number of rows inserted is 0, then you can manually get the ID of the row by a SELECT statement.
EDIT: LAST_INSERT_ID() was wrong here. I have edited the answer.