Postgres with Java I can't insert data

问题

I tried to make an insert to my postgres database with Java. I have default configuration for my local database.

I want to put some data in a table and I have some issues.

Here is the code :

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.util.logging.Level;
import java.util.logging.Logger;

public static void main(String[] args) {

    Connection con = null;
    PreparedStatement pst = null;

    String url = "jdbc:postgresql://localhost/postgres";
    String user = "postgres";
    String password = "thanassis";

    try {


        con = DriverManager.getConnection(url, user, password);

        String stm = "INSERT INTO TEST2(ID) VALUES(?)";
        pst = con.prepareStatement(stm);
        pst.setInt(1, 1);

        pst.executeUpdate(); 

    } catch (SQLException ex) {
        Logger lgr = Logger.getLogger(PreparedStatement.class.getName());
        lgr.log(Level.SEVERE, ex.getMessage(), ex);

    } finally {

        try {
            if (pst != null) {
                pst.close();
            }
            if (con != null) {
                con.close();
            }

        } catch (SQLException ex) {
            Logger lgr = Logger.getLogger(PreparedStatement.class.getName());
            lgr.log(Level.SEVERE, ex.getMessage(), ex);
        }
    }
}

And here the exceptions

SEVERE: ERROR: relation "test2" does not exist
  Position: 13
org.postgresql.util.PSQLException: ERROR: relation "test2" does not exist
  Position: 13
    at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2101)
    at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1834)
    at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:255)
    at org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:510)
    at org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:386)
    at org.postgresql.jdbc2.AbstractJdbc2Statement.executeUpdate(AbstractJdbc2Statement.java:332)
    at test.Test.main(Test.java:30)

回答1:

Your table is called TEST2 not test2. Apparently you created it using double quotes, which makes Postgres (and other standard-compliant DBMS) case-sensitive.

Because of that you now have to enclose the table in name in double quotes each time you refer to it.

String stm = "INSERT INTO \"TEST2\"(ID) VALUES(?)";

Most probably this is not what you intended, so just re-recreate the table without using double quotes around the identifiers:

CREATE TABLE test2
(
  ...
)

create a different table than:

CREATE TABLE "test2"
(
  ...
)

If you do not want to re-create the tables, you can rename them:

alter table "TEST2" rename to test2;

回答2:

Table test2 doesn't exist. Try to login to PostgreSQL and check this table.

You can list all existing tables in the database with command line utility

psql -d postgres
\dt

回答3:

Check for the schema in which you create the table test2. If it is one of the schemas not in the search path, then you have two options:-

Add the schema to your search_path(comma separated list in the file postgres.conf)
Refer to the table by prepending schema name and dot to the table name. For example if the concerned table test2 is in my_schema, then your query should be
insert into my_schema.test2(ID) values(?).

来源：https://stackoverflow.com/questions/12866326/postgres-with-java-i-cant-insert-data

标签

java

postgresql

sql-insert

quoted-identifier