feat(postgres_java): add classes
This commit is contained in:
parent
6ee110e8ef
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72c4b2bb5d
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package de.swingbe.postgres_java;
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import java.sql.Connection;
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import java.sql.DriverManager;
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import java.sql.SQLException;
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import java.sql.Statement;
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import java.util.logging.Level;
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import java.util.logging.Logger;
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public class JavaPostgreSqlBatchUpdates {
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public static void main(String[] args) {
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//connection URL for the postgres database
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//jdbc:postgresql://<host>:<port>/<database name>
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String url = "jdbc:postgresql://localhost:5432/testdb";
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String user = "usr";
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String password = "#password";
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try (Connection con = DriverManager.getConnection(url, user, password)) {
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try (Statement st = con.createStatement()) {
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//autocommit should always be turned off when doing batch updates
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con.setAutoCommit(false);
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//create a new table called friends and insert five rows into it
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st.addBatch("DROP TABLE IF EXISTS friends");
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st.addBatch("CREATE TABLE friends(id serial, name VARCHAR(10))");
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st.addBatch("INSERT INTO friends(name) VALUES ('Jane')");
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st.addBatch("INSERT INTO friends(name) VALUES ('Tom')");
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st.addBatch("INSERT INTO friends(name) VALUES ('Rebecca')");
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st.addBatch("INSERT INTO friends(name) VALUES ('Jim')");
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st.addBatch("INSERT INTO friends(name) VALUES ('Robert')");
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//method returns an array of committed changes
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int[] counts = st.executeBatch();
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con.commit();
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System.out.println("Committed " + counts.length + " updates");
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} catch (SQLException ex) {
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if (con != null) {
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try {
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con.rollback();
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} catch (SQLException ex1) {
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Logger lgr = Logger.getLogger(JavaPostgreSqlBatchUpdates.class.getName());
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lgr.log(Level.WARNING, ex1.getMessage(), ex1);
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}
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}
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Logger lgr = Logger.getLogger(JavaPostgreSqlBatchUpdates.class.getName());
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lgr.log(Level.SEVERE, ex.getMessage(), ex);
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}
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} catch (SQLException ex) {
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Logger lgr = Logger.getLogger(JavaPostgreSqlBatchUpdates.class.getName());
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lgr.log(Level.SEVERE, ex.getMessage(), ex);
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}
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}
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}
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package de.swingbe.postgres_java;
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import java.sql.*;
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import java.util.Formatter;
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import java.util.logging.Level;
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import java.util.logging.Logger;
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public class JavaPostgreSqlColumnHeaders {
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public static void main(String[] args) {
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//connection URL for the postgres database
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//jdbc:postgresql://<host>:<port>/<database name>
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String url = "jdbc:postgresql://localhost:5432/testdb";
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String user = "usr";
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String password = "#password";
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//sql statement that joins authors with their books
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String query = "SELECT name, title From authors, books WHERE authors.id=books.author_id";
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try (Connection con = DriverManager.getConnection(url, user, password); PreparedStatement pst = con.prepareStatement(query); ResultSet rs = pst.executeQuery()) {
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//to get the column names you need this object
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ResultSetMetaData meta = rs.getMetaData();
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String colname1 = meta.getColumnName(1);
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String colname2 = meta.getColumnName(2);
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//print column names
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Formatter fmt1 = new Formatter();
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fmt1.format("%-21s%s", colname1, colname2);
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System.out.println(fmt1);
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//print data
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while (rs.next()) {
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Formatter fmt2 = new Formatter();
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fmt2.format("%-21s", rs.getString(1));
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System.out.print(fmt2);
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System.out.println(rs.getString(2));
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}
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} catch (SQLException ex) {
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Logger lgr = Logger.getLogger(JavaPostgreSqlColumnHeaders.class.getName());
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lgr.log(Level.SEVERE, ex.getMessage(), ex);
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}
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}
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}
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package de.swingbe.postgres_java;
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import org.postgresql.copy.CopyManager;
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import org.postgresql.core.BaseConnection;
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import java.io.FileInputStream;
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import java.io.IOException;
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import java.io.InputStreamReader;
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import java.nio.charset.StandardCharsets;
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import java.sql.Connection;
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import java.sql.DriverManager;
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import java.sql.SQLException;
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import java.util.logging.Level;
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import java.util.logging.Logger;
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public class JavaPostgreSqlCopyFromTextFile {
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public static void main(String[] args) {
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//connection URL for the postgres database
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//jdbc:postgresql://<host>:<port>/<database name>
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String url = "jdbc:postgresql://localhost:5432/testdb";
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String user = "usr";
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String password = "#password";
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try (Connection con = DriverManager.getConnection(url, user, password)) {
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CopyManager cm = new CopyManager((BaseConnection) con);
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String fileName = "src/main/resources/friends.txt";
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try (FileInputStream fis = new FileInputStream(fileName); InputStreamReader isr = new InputStreamReader(fis, StandardCharsets.UTF_8)) {
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cm.copyIn("COPY friends FROM STDIN WITH DELIMITER ','", isr);
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}
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} catch (SQLException | IOException ex) {
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Logger lgr = Logger.getLogger(JavaPostgreSqlCopyFromTextFile.class.getName());
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lgr.log(Level.SEVERE, ex.getMessage(), ex);
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}
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}
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}
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package de.swingbe.postgres_java;
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import org.postgresql.copy.CopyManager;
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import org.postgresql.core.BaseConnection;
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import java.io.FileOutputStream;
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import java.io.IOException;
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import java.io.OutputStreamWriter;
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import java.nio.charset.StandardCharsets;
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import java.sql.Connection;
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import java.sql.DriverManager;
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import java.sql.SQLException;
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import java.util.logging.Level;
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import java.util.logging.Logger;
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public class JavaPostgreSqlCopyToTextFile {
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public static void main(String[] args) {
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//connection URL for the postgres database
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//jdbc:postgresql://<host>:<port>/<database name>
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String url = "jdbc:postgresql://localhost:5432/testdb";
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String user = "usr";
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String password = "#password";
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try {
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Connection con = DriverManager.getConnection(url, user, password);
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CopyManager cm = new CopyManager((BaseConnection) con);
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String fileName = "src/main/resources/friends.txt";
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try (FileOutputStream fos = new FileOutputStream(fileName); OutputStreamWriter osw = new OutputStreamWriter(fos, StandardCharsets.UTF_8)) {
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cm.copyOut("COPY friends TO STDOUT WITH DELIMITER AS ','", osw);
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} catch (IOException e) {
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e.printStackTrace();
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}
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} catch (SQLException ex) {
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Logger lgr = Logger.getLogger(JavaPostgreSqlCopyToTextFile.class.getName());
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lgr.log(Level.SEVERE, ex.getMessage(), ex);
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}
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}
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}
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package de.swingbe.postgres_java;
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import java.sql.*;
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import java.util.logging.Level;
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import java.util.logging.Logger;
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public class JavaPostgreSqlListTables {
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public static void main(String[] args) {
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//connection URL for the postgres database
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//jdbc:postgresql://<host>:<port>/<database name>
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String url = "jdbc:postgresql://localhost:5432/testdb";
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String user = "usr";
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String password = "#password";
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String query = "SELECT table_name FROM information_schema.tables " + "WHERE table_schema = 'public'";
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try (Connection con = DriverManager.getConnection(url, user, password); PreparedStatement pst = con.prepareStatement(query); ResultSet rs = pst.executeQuery()) {
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while (rs.next()) {
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System.out.println(rs.getString(1));
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}
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} catch (SQLException ex) {
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Logger lgr = Logger.getLogger(JavaPostgreSqlListTables.class.getName());
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lgr.log(Level.SEVERE, ex.getMessage(), ex);
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}
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}
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}
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package de.swingbe.postgres_java;
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import java.sql.*;
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import java.util.logging.Level;
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import java.util.logging.Logger;
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public class JavaPostgreSqlMultipleStatements {
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public static void main(String[] args) {
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//connection URL for the postgres database
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//jdbc:postgresql://<host>:<port>/<database name>
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String url = "jdbc:postgresql://localhost:5432/testdb";
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String user = "usr";
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String password = "#password";
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String query = "SELECT id, name FROM authors WHERE Id=1;" + "SELECT id, name FROM authors WHERE Id=2;" + "SELECT id, name FROM authors WHERE Id=3";
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try (Connection con = DriverManager.getConnection(url, user, password); PreparedStatement pst = con.prepareStatement(query)) {
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boolean isResult = pst.execute();
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if (isResult) {
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System.out.println("The method returns a boolean value indicating if the first result is a ResultSet object");
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}
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do {
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try (ResultSet rs = pst.getResultSet()) {
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while (rs.next()) {
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System.out.print(rs.getInt(1));
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System.out.print(": ");
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System.out.println(rs.getString(2));
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}
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isResult = pst.getMoreResults();
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}
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} while (isResult);
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} catch (SQLException ex) {
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Logger lgr = Logger.getLogger(JavaPostgreSqlMultipleStatements.class.getName());
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lgr.log(Level.SEVERE, ex.getMessage(), ex);
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}
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}
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}
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@ -11,18 +11,20 @@ public class JavaPostgreSqlPrepared {
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public static void main(String[] args) {
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//connection URL for the postgres database
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//jdbc:postgresql://<host>:<port>/<database name>
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String url = "jdbc:postgresql://localhost:5432/testdb";
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String user = "usr";
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String password = "#password";
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//add new author to authors table
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//add new author to author's table
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int id = 6;
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String author = "Trygve Gulbranssen";
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String query = "INSERT INTO authors(id, name) VALUES(?, ?)";
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//create prepared statement using placeholders instead of directly writing values
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try (Connection con = DriverManager.getConnection(url, user, password);
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PreparedStatement pst = con.prepareStatement(query)) {
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try (Connection con = DriverManager.getConnection(url, user, password); PreparedStatement pst = con.prepareStatement(query)) {
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//bound integer to placeholder
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pst.setInt(1, id);
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@ -8,7 +8,10 @@ public class JavaPostgreSqlRetrieve {
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public static void main(String[] args) {
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//connection URL for the postgres database
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//jdbc:postgresql://<host>:<port>/<database name>
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String url = "jdbc:postgresql://localhost:5432/testdb";
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String user = "usr";
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String password = "#password";
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@ -16,9 +19,7 @@ public class JavaPostgreSqlRetrieve {
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String query = "SELECT * FROM authors";
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//create prepared statement using placeholders instead of directly writing values
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try (Connection con = DriverManager.getConnection(url, user, password);
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PreparedStatement pst = con.prepareStatement(query);
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ResultSet rs = pst.executeQuery()) {
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try (Connection con = DriverManager.getConnection(url, user, password); PreparedStatement pst = con.prepareStatement(query); ResultSet rs = pst.executeQuery()) {
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//advance cursor to the next record
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//return false if there are no more records in the result set
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package de.swingbe.postgres_java;
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import java.sql.Connection;
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import java.sql.DriverManager;
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import java.sql.SQLException;
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import java.sql.Statement;
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import java.util.logging.Level;
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import java.util.logging.Logger;
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public class JavaPostgreSqlTransactionEx {
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public static void main(String[] args) {
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//connection URL for the postgres database
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//jdbc:postgresql://<host>:<port>/<database name>
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String url = "jdbc:postgresql://localhost:5432/testdb";
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String user = "usr";
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String password = "#password";
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try (Connection con = DriverManager.getConnection(url, user, password)) {
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try (Statement st = con.createStatement()) {
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//to work with transactions, you must set autocommit to false
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con.setAutoCommit(false);
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st.executeUpdate("UPDATE authors SET name = 'Leo Tolstoy' " + "WHERE Id = 1");
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st.executeUpdate("UPDATE books SET title = 'War and Peace' " + "WHERE Id = 1");
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st.executeUpdate("UPDATE books SET titl = 'Anna Karenina' " + "WHERE Id = 2");
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//ff autocommit is turned off, you must explicitly call the commit method
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con.commit();
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} catch (SQLException ex) {
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if (con != null) {
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try {
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con.rollback();
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} catch (SQLException ex1) {
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Logger lgr = Logger.getLogger(JavaPostgreSqlTransactionEx.class.getName());
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lgr.log(Level.WARNING, ex1.getMessage(), ex1);
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}
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}
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Logger lgr = Logger.getLogger(JavaPostgreSqlTransactionEx.class.getName());
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lgr.log(Level.SEVERE, ex.getMessage(), ex);
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}
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} catch (SQLException ex) {
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Logger lgr = Logger.getLogger(JavaPostgreSqlTransactionEx.class.getName());
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lgr.log(Level.SEVERE, ex.getMessage(), ex);
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}
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}
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}
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@ -8,18 +8,22 @@ public class JavaPostgreSqlVersion {
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public static void main(String[] args) {
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//connection URL
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String url = "jdbc:postgresql://192.168.178.25:5432/testdb";
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String user = "user";
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String key = "key";
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//connection URL for the postgres database
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//jdbc:postgresql://<host>:<port>/<database name>
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String url = "jdbc:postgresql://localhost:5432/testdb";
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String user = "usr";
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String password = "#password";
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try (
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//establish connection
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Connection con = DriverManager.getConnection(url, user, key);
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Connection con = DriverManager.getConnection(url, user, password);
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//create object for sending SQL statements
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Statement st = con.createStatement();
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//execute SQL statement
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//rs is a table of data returned by a SQL statement
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//rs object is a table of data returned by a SQL statement
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ResultSet rs = st.executeQuery("SELECT VERSION()")) {
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while (rs.next()) {
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