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主题： Java实现获得MySQL数据库中所有表的记录总数可行方法

本主题由 koei123 于 2015-7-14 11:14:25 移动

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发表于：

2015-5-15 10:38:53 | [全部帖] [楼主帖]

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在MySQL中，可以通过SELECT COUNT(*) FROM table_name查询某个表中有多少条记录。如果想知道某个数据库中所有别的记录总数应该怎么做呢？本文给出两种可行的Java程序，解决该问题。

1. 首先确定数据库中有多少个表，然后对每个表执行SELECT COUNT(*) FROM table_name

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
public class Test {
      private static String driver = "com.mysql.jdbc.Driver";
      private static String url = "jdbc:mysql://127.0.0.1/";
      private static String db = "test";
      private static String user = "root";
      private static String pass = "test";
      static Connection conn = null;
      static Statement statement = null;
      static PreparedStatement ps = null;
      static ResultSet rs = null;
      static List<String> tables = new ArrayList<String>();
      public static void startMySQLConn() {
            try {
                  Class.forName(driver).newInstance();
                  conn = DriverManager.getConnection(url+db, user, pass);
                  if (!conn.isClosed()) {
                        System.out.println("Succeeded connecting to MySQL!");
                  }
                  statement = conn.createStatement();
            } catch (Exception e) {
                  e.printStackTrace();
            }
      }
      public static void closeMySQLConn() {
            if(conn != null){
                  try {
                        conn.close();
                        System.out.println("Database connection terminated!");
                  } catch (SQLException e) {
                        e.printStackTrace();
                  }
            }
      }
      public static void getTables() {
            String sql = "show tables;";
            try {
                  ps = conn.prepareStatement(sql);
                  rs = ps.executeQuery();
                  while (rs.next()) {
                        tables.add(rs.getString(1));
                  }
            } catch (Exception e) {
                  e.printStackTrace();
            }
      }
      public static long getDbSum() {
            long sum = 0;
            String sql = "select count(*) from ";
            try {
                  for(String tblName: tables) {
                        ps = conn.prepareStatement(sql + tblName + ";");
                        rs = ps.executeQuery();
                        while (rs.next()) {
                              sum += rs.getInt(1);
                        }
                  }
            } catch (Exception e) {
                  e.printStackTrace();
            }
            return sum;
      }
      public static void main(String[] args) {
            startMySQLConn();
            getTables();
            System.out.println(getDbSum());
            closeMySQLConn();
      }
}

2. 借助information_schema库的tables表

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
public class Test {
      private static String driver = "com.mysql.jdbc.Driver";
      private static String url = "jdbc:mysql://127.0.0.1/";
      private static String db = "test";
      private static String user = "root";
      private static String pass = "test";
      static Connection conn = null;
      static Statement statement = null;
      static PreparedStatement ps = null;
      static ResultSet rs = null;
      public static void startMySQLConn() {
            try {
                  Class.forName(driver).newInstance();
                  conn = DriverManager.getConnection(url+db, user, pass);
                  if (!conn.isClosed()) {
                        System.out.println("Succeeded connecting to MySQL!");
                  }
                  statement = conn.createStatement();
            } catch (Exception e) {
                  e.printStackTrace();
            }
      }
      public static void closeMySQLConn() {
            if(conn != null){
                  try {
                        conn.close();
                        System.out.println("Database connection terminated!");
                  } catch (SQLException e) {
                        e.printStackTrace();
                  }
            }
      }
      public static void useDB() {
            String sql = "use information_schema;";
            try {
                  ps = conn.prepareStatement(sql);
                  rs = ps.executeQuery();
            } catch (Exception e) {
                  e.printStackTrace();
            }
      }
      public static long getDbSum() {
            long sum = 0;
            String sql = "select table_name,table_rows from tables where TABLE_SCHEMA = '" +
            db + "' order by table_rows desc;";
            //System.out.println(sql);
            try {
                  ps = conn.prepareStatement(sql);
                  rs = ps.executeQuery();
                  while (rs.next()) {
                        sum += rs.getInt(2);
                  }
            } catch (Exception e) {
                  e.printStackTrace();
            }
            return sum;
      }
      public static void main(String[] args) {
            startMySQLConn();
            useDB();
            System.out.println(getDbSum());
            closeMySQLConn();
      }
}

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