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概述安装和环境设置语法数据类型创建数据库选择数据库删除数据库创建表删除表架构 Insert 查询 Select 查询运算符表达式 Where 子句 AND & OR 子句 Update 查询 Delete 查询 Like 子句 Limit 子句 Order By 子句 Group By 子句 With 子句 Having 子句 Distinct 关键字约束连接 Unions 子句 NULL 值 Alias 语法触发器索引 Alter Table 命令 Truncate 命令视图事务锁子查询自动增量权限日期/时间函数 & 运算符函数实用函数 C/C++ Java PHP Perl Python

高级PostgreSQL

约束连接 Unions 子句 NULL 值 Alias 语法触发器索引 Alter Table 命令 Truncate 命令视图事务锁子查询自动增量权限日期/时间函数 & 运算符函数实用函数

PostgreSQL接口

C/C++ Java PHP Perl Python

PostgreSQL 教程

更新时间2025-08-21

C/C++ PHP

安装

在我们的 Java 程序中开始使用 PostgreSQL 之前，我们需要确保在机器上设置了 PostgreSQL JDBC 和 Java。您可以查看 Java 教程以在您的机器上安装 Java。现在让我们检查如何设置 PostgreSQL JDBC 驱动程序。

从 postgresql-jdbc 存储库下载最新版本的 postgresql-(VERSION).jdbc.jar。
在您的类路径中添加下载的 jar 文件 postgresql-(VERSION).jdbc.jar，或者您可以将它与 -classpath 选项一起使用，如下面的示例中所述。

以下部分假设您对 Java JDBC 概念知之甚少。如果您没有，建议花半个小时阅读JDBC 教程，熟悉解释的概念以下。

连接数据库

以下 Java 代码显示了如何连接到现有数据库。如果数据库不存在，则创建它，最后返回一个数据库对象。

import java.sql.Connection;
import java.sql.DriverManager;

public class PostgreSQLJDBC {
   public static void main(String args[]) {
      Connection c = null;
      try {
         Class.forName("org.postgresql.Driver");
         c = DriverManager
            .getConnection("jdbc:postgresql://localhost:5432/testdb",
            "postgres", "123");
      } catch (Exception e) {
         e.printStackTrace();
         System.err.println(e.getClass().getName()+": "+e.getMessage());
         System.exit(0);
      }
      System.out.println("Opened database successfully");
   }
}

在编译和运行上述程序之前，在你的 PostgreSQL 安装目录中找到 pg_hba.conf 文件并添加以下行 −

# IPv4 local connections:
host    all         all         127.0.0.1/32          md5

您可以使用以下命令启动/重新启动 postgres 服务器以防它未运行 −

[root@host]# service postgresql restart
Stopping postgresql service:                               [  OK  ]
Starting postgresql service:                               [  OK  ]

现在，让我们编译并运行上面的程序来连接 testdb。在这里，我们使用 postgres 作为用户 ID，使用 123 作为密码来访问数据库。您可以根据您的数据库配置和设置更改此设置。我们还假设当前版本的 JDBC 驱动程序 postgresql-9.2-1002.jdbc3.jar 在当前路径中可用。

C:\JavaPostgresIntegration>javac PostgreSQLJDBC.java
C:\JavaPostgresIntegration>java -cp c:\tools\postgresql-9.2-1002.jdbc3.jar;C:\JavaPostgresIntegration PostgreSQLJDBC
Open database successfully

创建表

以下 Java 程序将用于在先前打开的数据库中创建表。确保您的目标数据库中没有此表。

import java.sql.*;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;

public class PostgreSQLJDBC {
   public static void main( String args[] ) {
      Connection c = null;
      Statement stmt = null;
      try {
         Class.forName("org.postgresql.Driver");
         c = DriverManager
            .getConnection("jdbc:postgresql://localhost:5432/testdb",
            "manisha", "123");
         System.out.println("Opened database successfully");

         stmt = c.createStatement();
         String sql = "CREATE TABLE COMPANY " +
            "(ID INT PRIMARY KEY     NOT NULL," +
            " NAME           TEXT    NOT NULL, " +
            " AGE            INT     NOT NULL, " +
            " ADDRESS        CHAR(50), " +
            " SALARY         REAL)";
         stmt.executeUpdate(sql);
         stmt.close();
         c.close();
      } catch ( Exception e ) {
         System.err.println( e.getClass().getName()+": "+ e.getMessage() );
         System.exit(0);
      }
      System.out.println("Table created successfully");
   }
}

程序编译执行后，会在 testdb 数据库中创建 COMPANY 表，并显示以下两行 −

Opened database successfully
Table created successfully

插入操作

以下 Java 程序显示了我们如何在上面示例中创建的 COMPANY 表中创建记录 −

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;

public class PostgreSQLJDBC {
   public static void main(String args[]) {
      Connection c = null;
      Statement stmt = null;
      try {
         Class.forName("org.postgresql.Driver");
         c = DriverManager
            .getConnection("jdbc:postgresql://localhost:5432/testdb",
            "manisha", "123");
         c.setAutoCommit(false);
         System.out.println("Opened database successfully");

         stmt = c.createStatement();
         String sql = "INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) "
            + "VALUES (1, 'Paul', 32, 'California', 20000.00 );";
         stmt.executeUpdate(sql);

         sql = "INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) "
            + "VALUES (2, 'Allen', 25, 'Texas', 15000.00 );";
         stmt.executeUpdate(sql);

         sql = "INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) "
            + "VALUES (3, 'Teddy', 23, 'Norway', 20000.00 );";
         stmt.executeUpdate(sql);

         sql = "INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) "
            + "VALUES (4, 'Mark', 25, 'Rich-Mond ', 65000.00 );";
         stmt.executeUpdate(sql);

         stmt.close();
         c.commit();
         c.close();
      } catch (Exception e) {
         System.err.println( e.getClass().getName()+": "+ e.getMessage() );
         System.exit(0);
      }
      System.out.println("Records created successfully");
   }
}

当上面的程序编译并执行时，它会在 COMPANY 表中创建给定的记录，并会显示以下两行 −

Opened database successfully
Records created successfully

SELECT 操作

以下 Java 程序展示了我们如何从上面示例中创建的 COMPANY 表中获取和显示记录 −

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

public class PostgreSQLJDBC {
   public static void main( String args[] ) {
      Connection c = null;
      Statement stmt = null;
      try {
         Class.forName("org.postgresql.Driver");
         c = DriverManager
            .getConnection("jdbc:postgresql://localhost:5432/testdb",
            "manisha", "123");
         c.setAutoCommit(false);
         System.out.println("Opened database successfully");

         stmt = c.createStatement();
         ResultSet rs = stmt.executeQuery( "SELECT * FROM COMPANY;" );
         while ( rs.next() ) {
            int id = rs.getInt("id");
            String  name = rs.getString("name");
            int age  = rs.getInt("age");
            String  address = rs.getString("address");
            float salary = rs.getFloat("salary");
            System.out.println( "ID = " + id );
            System.out.println( "NAME = " + name );
            System.out.println( "AGE = " + age );
            System.out.println( "ADDRESS = " + address );
            System.out.println( "SALARY = " + salary );
            System.out.println();
         }
         rs.close();
         stmt.close();
         c.close();
      } catch ( Exception e ) {
         System.err.println( e.getClass().getName()+": "+ e.getMessage() );
         System.exit(0);
      }
      System.out.println("Operation done successfully");
   }
}

程序编译执行后会产生如下结果 −

Opened database successfully
ID = 1
NAME = Paul
AGE = 32
ADDRESS = California
SALARY = 20000.0

ID = 2
NAME = Allen
AGE = 25
ADDRESS = Texas
SALARY = 15000.0

ID = 3
NAME = Teddy
AGE = 23
ADDRESS = Norway
SALARY = 20000.0

ID = 4
NAME = Mark
AGE = 25
ADDRESS = Rich-Mond
SALARY = 65000.0

Operation done successfully

UPDATE 操作

以下 Java 代码显示了我们如何使用 UPDATE 语句更新任何记录，然后从我们的 COMPANY 表中获取并显示更新的记录 −

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

public class PostgreSQLJDBC {
   public static void main( String args[] ) {
      Connection c = null;
      Statement stmt = null;
      try {
         Class.forName("org.postgresql.Driver");
         c = DriverManager
            .getConnection("jdbc:postgresql://localhost:5432/testdb",
            "manisha", "123");
         c.setAutoCommit(false);
         System.out.println("Opened database successfully");

         stmt = c.createStatement();
         String sql = "UPDATE COMPANY set SALARY = 25000.00 where ID=1;";
         stmt.executeUpdate(sql);
         c.commit();

         ResultSet rs = stmt.executeQuery( "SELECT * FROM COMPANY;" );
         while ( rs.next() ) {
            int id = rs.getInt("id");
            String  name = rs.getString("name");
            int age  = rs.getInt("age");
            String  address = rs.getString("address");
            float salary = rs.getFloat("salary");
            System.out.println( "ID = " + id );
            System.out.println( "NAME = " + name );
            System.out.println( "AGE = " + age );
            System.out.println( "ADDRESS = " + address );
            System.out.println( "SALARY = " + salary );
            System.out.println();
         }
         rs.close();
         stmt.close();
         c.close();
      } catch ( Exception e ) {
         System.err.println( e.getClass().getName()+": "+ e.getMessage() );
         System.exit(0);
      }
      System.out.println("Operation done successfully");
   }
}

程序编译执行后会产生如下结果 −

Opened database successfully
ID = 2
NAME = Allen
AGE = 25
ADDRESS = Texas
SALARY = 15000.0

ID = 3
NAME = Teddy
AGE = 23
ADDRESS = Norway
SALARY = 20000.0

ID = 4
NAME = Mark
AGE = 25
ADDRESS = Rich-Mond
SALARY = 65000.0

ID = 1
NAME = Paul
AGE = 32
ADDRESS = California
SALARY = 25000.0

Operation done successfully

DELETE 操作

以下 Java 代码显示了我们如何使用 DELETE 语句删除任何记录，然后从我们的 COMPANY 表中获取并显示剩余记录 −

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

public class PostgreSQLJDBC6 {
   public static void main( String args[] ) {
      Connection c = null;
      Statement stmt = null;
      try {
         Class.forName("org.postgresql.Driver");
         c = DriverManager
            .getConnection("jdbc:postgresql://localhost:5432/testdb",
            "manisha", "123");
         c.setAutoCommit(false);
         System.out.println("Opened database successfully");

         stmt = c.createStatement();
         String sql = "DELETE from COMPANY where ID = 2;";
         stmt.executeUpdate(sql);
         c.commit();

         ResultSet rs = stmt.executeQuery( "SELECT * FROM COMPANY;" );
         while ( rs.next() ) {
            int id = rs.getInt("id");
            String  name = rs.getString("name");
            int age  = rs.getInt("age");
            String  address = rs.getString("address");
            float salary = rs.getFloat("salary");
            System.out.println( "ID = " + id );
            System.out.println( "NAME = " + name );
            System.out.println( "AGE = " + age );
            System.out.println( "ADDRESS = " + address );
            System.out.println( "SALARY = " + salary );
            System.out.println();
         }
         rs.close();
         stmt.close();
         c.close();
      } catch ( Exception e ) {
         System.err.println( e.getClass().getName()+": "+ e.getMessage() );
         System.exit(0);
      }
      System.out.println("Operation done successfully");
   }
}

程序编译执行后会产生如下结果 −

Opened database successfully
ID = 3
NAME = Teddy
AGE = 23
ADDRESS = Norway
SALARY = 20000.0

ID = 4
NAME = Mark
AGE = 25
ADDRESS = Rich-Mond
SALARY = 65000.0

ID = 1
NAME = Paul
AGE = 32
ADDRESS = California
SALARY = 25000.0
Operation done successfully

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