如何计算行–计数（*）和Java
SQL Count()函数返回表中的行数。使用此方法，您可以获取表中的行数。
select count(*) from TABLE_NAME;
让我们使用CREATE语句在MySQL数据库中创建一个名称为cricketers_data 的表，如下所示-
CREATE TABLE cricketers_data( First_Name VARCHAR(255), Last_Name VARCHAR(255), Date_Of_Birth date, Place_Of_Birth VARCHAR(255), Country VARCHAR(255), );
现在，我们将使用INSERT语句在cricketers_data 表中插入5条记录-
insert into cricketers_data values('Shikhar', 'Dhawan', DATE('1981-12-05'), 'Delhi', 'India');
insert into cricketers_data values('Jonathan', 'Trott', DATE('1981-04-22'), 'CapeTown', 'SouthAfrica');
insert into cricketers_data values('Kumara', 'Sangakkara', DATE('1977-10-27'), 'Matale', 'Srilanka');
insert into cricketers_data values('Virat', 'Kohli', DATE('1988-11-05'), 'Delhi', 'India');
insert into cricketers_data values('Rohit', 'Sharma', DATE('1987-04-30'), 'Nagpur', 'India');以下JDBC程序建立与MySQL的连接，并在名为cricketers_data的表中显示行数。
示例
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class Count_Example {
public static void main(String args[]) throws Exception {
//注册驱动程序
DriverManager.registerDriver(new com.mysql.jdbc.Driver());
//获得连接
String mysqlUrl = "jdbc:mysql://localhost/mydatabase";
Connection con = DriverManager.getConnection(mysqlUrl, "root", "password");
System.out.println("Connection established......");
//创建Statement对象
Statement stmt = con.createStatement();
//查询以获取表中的行数
String query = "select count(*) from Cricketers_Data";
//执行查询
ResultSet rs = stmt.executeQuery(query);
//检索结果
rs.next();
int count = rs.getInt(1);
System.out.println("Number of records in the cricketers_data table: "+count);
}
}输出结果
Connection established...... Number of records in the cricketers_data table: 5