using System;
using System.Collections.Generic;
using System.Data;
using MySql.Data.MySqlClient;
namespace WordWorld
{
public class MySQLHelper
{
private string connectionString;
public MySQLHelper(string connectionString)
{
this.connectionString = connectionString;
}
// 执行不返回结果集的SQL语句
public int ExecuteNonQuery(string sql, params MySqlParameter[] parameters)
{
using (MySqlConnection connection = new MySqlConnection(connectionString))
{
using (MySqlCommand command = new MySqlCommand(sql, connection))
{
// 添加参数
command.Parameters.AddRange(parameters);
try
{
// 打开连接
connection.Open();
// 执行SQL语句并返回影响行数
return command.ExecuteNonQuery();
}
catch (Exception e)
{
Console.WriteLine("发现异常:"+e.Message);
return 0;
}
finally
{
connection.Close();
connection.Dispose();
}
}
}
}
// 执行一个查询，并返回结果集中第一行的第一列
public object ExecuteScalar(string sql, params MySqlParameter[] parameters)
{
using (MySqlConnection connection = new MySqlConnection(connectionString))
{
using (MySqlCommand command = new MySqlCommand(sql, connection))
{
// 添加参数
command.Parameters.AddRange(parameters);
try
{
// 打开连接
connection.Open();
// 执行SQL查询并返回第一行第一列的值
return command.ExecuteScalar();
}
catch (Exception e)
{
Console.WriteLine("发现异常:" + e.Message);
return 0;
}
finally
{
connection.Close();
connection.Dispose();
}
}
}
}
// 执行一个查询，并返回结果集
public DataTable ExecuteQuery(string sql, Dictionary<string, object> data)
{
using (MySqlConnection connection = new MySqlConnection(connectionString))
{
using (MySqlCommand command = new MySqlCommand(sql, connection))
{
// 添加参数
command.Parameters.AddRange(ToMySqlParameters(data));
try
{
// 打开连接
connection.Open();
// 创建DataAdapter和DataTable对象，并填充数据
using (MySqlDataAdapter adapter = new MySqlDataAdapter(command))
{
DataTable dataTable = new DataTable();
adapter.Fill(dataTable);
return dataTable;
}
}
catch (Exception e)
{
Console.WriteLine("发现异常:" + e.Message);
return null;
}
finally
{
connection.Close();
connection.Dispose();
}
}
}
}
// 执行一个查询，并将结果集映射到一个对象列表
public List<T> ExecuteQuery<T>(string sql, Func<IDataRecord, T> selector, Dictionary<string, object> data)
{
using (MySqlConnection connection = new MySqlConnection(connectionString))
{
using (MySqlCommand command = new MySqlCommand(sql, connection))
{
// 添加参数
command.Parameters.AddRange(ToMySqlParameters(data));
try
{
// 打开连接
connection.Open();
// 创建DataReader对象并读取数据，将每行数据映射到对象并添加到列表中
using (MySqlDataReader reader = command.ExecuteReader())
{
List<T> list = new List<T>();
while (reader.Read())
{
list.Add(selector(reader));
}
return list;
}
}
catch (Exception e)
{
Console.WriteLine("发现异常:" + e.Message);
return null;
}
finally
{
connection.Close();
connection.Dispose();
}
}
}
}
// 向数据库中插入数据
public int Insert(string tableName, Dictionary<string, object> data)
{
string[] columns = new string[data.Count];
object[] values = new object[data.Count];
int i = 0;
foreach (KeyValuePair<string, object> item in data)
{
// 获取列名和值
columns[i] = item.Key;
values[i] = item.Value;
i++;
}
string sql = string.Format("INSERT INTO {0} ({1}) VALUES ({2})", tableName, string.Join(",", columns), "@" + string.Join(",@", columns));
// 将Dictionary转换为MySqlParameter数组，并执行SQL语句
return ExecuteNonQuery(sql, ToMySqlParameters(data));
}
// 更新数据库中的数据
public int Update(string tableName, Dictionary<string, object> data, string whereClause = "")
{
string[] setValues = new string[data.Count];
int i = 0;
foreach (KeyValuePair<string, object> item in data)
{
// 获取列名和值
setValues[i] = string.Format("{0}=@{0}", item.Key);
i++;
}
string sql = string.Format("UPDATE {0} SET {1}", tableName, string.Join(",", setValues));
if (!string.IsNullOrEmpty(whereClause))
{
sql += " WHERE " + whereClause;
}
// 将Dictionary转换为MySqlParameter数组，并执行SQL语句
return ExecuteNonQuery(sql, ToMySqlParameters(data));
}
// 删除数据库中的数据
public int Delete(string tableName, string whereClause = "")
{
string sql = string.Format("DELETE FROM {0}", tableName);
if (!string.IsNullOrEmpty(whereClause))
{
sql += " WHERE " + whereClause;
}
// 执行SQL语句并返回影响
return ExecuteNonQuery(sql);
}
// 将Dictionary转换为MySqlParameter数组
private MySqlParameter[] ToMySqlParameters(Dictionary<string, object> data)
{
List<MySqlParameter> parameters = new List<MySqlParameter>();
foreach (KeyValuePair<string, object> item in data)
{
parameters.Add(new MySqlParameter("@" + item.Key, item.Value));
}
return parameters.ToArray();
}
}
}
调用
// 查询所有数据
DataTable dataTable = mySQLHelper.ExecuteQuery("SELECT * FROM myTable");
foreach (DataRow row in dataTable.Rows)
{
Console.WriteLine(row["id"].ToString());
}
// 查询
Dictionary<string, object> data = new Dictionary<string, object>();
data.Add("accoumnt", "admin");
data.Add("password", "admin");
object value = mySQLHelper.ExecuteScalar("SELECT COUNT(*) FROM myTable",ToMySqlParameters(data));
Console.WriteLine(value.ToString());
// 查询并映射到对象列表
List<MyClass> list = mySQLHelper.ExecuteQuery("SELECT * FROM myTable", r => new MyClass
{
Column1 = r["column1"].ToString(),
Column2 = int.Parse(r["column2"].ToString())
});
// 插入数据
Dictionary<string, object> data = new Dictionary<string, object>();
data.Add("column1", "value1");
data.Add("column2", 123);
int result = mySQLHelper.Insert("myTable", data);
// 更新数据
Dictionary<string, object> data = new Dictionary<string, object>();
data.Add("column1", "value2");
data.Add("column2", 456);
int result = mySQLHelper.Update("myTable", data, "id=1");
// 删除数据
int result = mySQLHelper.Delete("myTable", "id=1");
参考：