用Java Postgres我不能插入数据

Question

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);
        }
    }
}

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)

Answer 1

您的表称为test2而不是test2。显然，您使用双引号创建了它，这使得Postgres（和其他符合标准的DBMS）区分大小写。

因此，您现在必须在每次引用表时用双引号将表的名称括起来。

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

这很可能不是您想要的，所以只需重新创建表，而不在标识符周围使用双引号：

CREATE TABLE test2
(
  ...
)

CREATE TABLE "test2"
(
  ...
)

alter table "TEST2" rename to test2;