实例介绍
【实例简介】需要引用 MySql.Data.MySqlClient.dll,引用方法可 Install-Package MySql.Data -Version 8.0.13
【实例截图】
【实例截图】
【核心代码】
using System;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Linq;
using System.Web;
using System.Data;
using MySql.Data.MySqlClient;
using System.Configuration;
using System.Data.Common;
using System.Collections.Generic;
namespace wx_webapi.ajax
{
public class DbHelper
{
public static string connectionString = System.Configuration.ConfigurationSettings.AppSettings["ConnectionString"];
public DbHelper()
{
}
#region 公用方法
/// <summary>
/// 得到最大值
/// </summary>
/// <param name="FieldName"></param>
/// <param name="TableName"></param>
/// <returns></returns>
public int GetMaxID(string FieldName, string TableName)
{
string strsql = "select max(" FieldName ") 1 from " TableName;
object obj = GetSingle(strsql);
if (obj == null)
{
return 1;
}
else
{
return int.Parse(obj.ToString());
}
}
/// <summary>
/// 是否存在
/// </summary>
/// <param name="strSql"></param>
/// <returns></returns>
public bool Exists(string strSql)
{
object obj = GetSingle(strSql);
int cmdresult;
if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value)))
{
cmdresult = 0;
}
else
{
cmdresult = int.Parse(obj.ToString());
}
if (cmdresult == 0)
{
return false;
}
else
{
return true;
}
}
/// <summary>
/// 是否存在（基于MySqlParameter）
/// </summary>
/// <param name="strSql"></param>
/// <param name="cmdParms"></param>
/// <returns></returns>
public bool Exists(string strSql, params MySqlParameter[] cmdParms)
{
object obj = GetSingle(strSql, cmdParms);
int cmdresult;
if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value)))
{
cmdresult = 0;
}
else
{
cmdresult = int.Parse(obj.ToString());
}
if (cmdresult == 0)
{
return false;
}
else
{
return true;
}
}
#endregion
#region 执行简单SQL语句
/// <summary>
/// 执行SQL语句，返回影响的记录数
/// </summary>
/// <param name="SQLString">SQL语句</param>
/// <returns>影响的记录数</returns>
public int ExecuteSql(string SQLString)
{
using (MySqlConnection connection = new MySqlConnection(connectionString))
{
using (MySqlCommand cmd = new MySqlCommand(SQLString, connection))
{
try
{
connection.Open();
int rows = cmd.ExecuteNonQuery();
return rows;
}
catch (MySql.Data.MySqlClient.MySqlException e)
{
connection.Close();
throw e;
}
}
}
}
public int ExecuteSqlByTime(string SQLString, int Times)
{
using (MySqlConnection connection = new MySqlConnection(connectionString))
{
using (MySqlCommand cmd = new MySqlCommand(SQLString, connection))
{
try
{
connection.Open();
cmd.CommandTimeout = Times;
int rows = cmd.ExecuteNonQuery();
return rows;
}
catch (MySql.Data.MySqlClient.MySqlException e)
{
connection.Close();
throw e;
}
}
}
}
/// <summary>
/// 执行多条SQL语句，实现数据库事务。
/// </summary>
/// <param name="SQLStringList">多条SQL语句</param>
public int ExecuteSqlTran(List<String> SQLStringList)
{
using (MySqlConnection conn = new MySqlConnection(connectionString))
{
conn.Open();
MySqlCommand cmd = new MySqlCommand();
cmd.Connection = conn;
MySqlTransaction tx = conn.BeginTransaction();
cmd.Transaction = tx;
try
{
int count = 0;
for (int n = 0; n < SQLStringList.Count; n )
{
string strsql = SQLStringList[n];
if (strsql.Trim().Length > 1)
{
cmd.CommandText = strsql;
count = cmd.ExecuteNonQuery();
}
}
tx.Commit();
return count;
}
catch
{
tx.Rollback();
return 0;
}
}
}
/// <summary>
/// 执行带一个存储过程参数的的SQL语句。
/// </summary>
/// <param name="SQLString">SQL语句</param>
/// <param name="content">参数内容,比如一个字段是格式复杂的文章，有特殊符号，可以通过这个方式添加</param>
/// <returns>影响的记录数</returns>
public int ExecuteSql(string SQLString, string content)
{
using (MySqlConnection connection = new MySqlConnection(connectionString))
{
MySqlCommand cmd = new MySqlCommand(SQLString, connection);
MySql.Data.MySqlClient.MySqlParameter myParameter = new MySql.Data.MySqlClient.MySqlParameter("@content", SqlDbType.NText);
myParameter.Value = content;
cmd.Parameters.Add(myParameter);
try
{
connection.Open();
int rows = cmd.ExecuteNonQuery();
return rows;
}
catch (MySql.Data.MySqlClient.MySqlException e)
{
throw e;
}
finally
{
cmd.Dispose();
connection.Close();
}
}
}
/// <summary>
/// 执行带一个存储过程参数的的SQL语句。
/// </summary>
/// <param name="SQLString">SQL语句</param>
/// <param name="content">参数内容,比如一个字段是格式复杂的文章，有特殊符号，可以通过这个方式添加</param>
/// <returns>影响的记录数</returns>
public object ExecuteSqlGet(string SQLString, string content)
{
using (MySqlConnection connection = new MySqlConnection(connectionString))
{
MySqlCommand cmd = new MySqlCommand(SQLString, connection);
MySql.Data.MySqlClient.MySqlParameter myParameter = new MySql.Data.MySqlClient.MySqlParameter("@content", SqlDbType.NText);
myParameter.Value = content;
cmd.Parameters.Add(myParameter);
try
{
connection.Open();
object obj = cmd.ExecuteScalar();
if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value)))
{
return null;
}
else
{
return obj;
}
}
catch (MySql.Data.MySqlClient.MySqlException e)
{
throw e;
}
finally
{
cmd.Dispose();
connection.Close();
}
}
}
/// <summary>
/// 向数据库里插入图像格式的字段(和上面情况类似的另一种实例)
/// </summary>
/// <param name="strSQL">SQL语句</param>
/// <param name="fs">图像字节,数据库的字段类型为image的情况</param>
/// <returns>影响的记录数</returns>
public int ExecuteSqlInsertImg(string strSQL, byte[] fs)
{
using (MySqlConnection connection = new MySqlConnection(connectionString))
{
MySqlCommand cmd = new MySqlCommand(strSQL, connection);
MySql.Data.MySqlClient.MySqlParameter myParameter = new MySql.Data.MySqlClient.MySqlParameter("@fs", SqlDbType.Image);
myParameter.Value = fs;
cmd.Parameters.Add(myParameter);
try
{
connection.Open();
int rows = cmd.ExecuteNonQuery();
return rows;
}
catch (MySql.Data.MySqlClient.MySqlException e)
{
throw e;
}
finally
{
cmd.Dispose();
connection.Close();
}
}
}
/// <summary>
/// 执行一条计算查询结果语句，返回查询结果（object）。
/// </summary>
/// <param name="SQLString">计算查询结果语句</param>
/// <returns>查询结果（object）</returns>
public object GetSingle(string SQLString)
{
using (MySqlConnection connection = new MySqlConnection(connectionString))
{
using (MySqlCommand cmd = new MySqlCommand(SQLString, connection))
{
try
{
connection.Open();
object obj = cmd.ExecuteScalar();
if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value)))
{
return null;
}
else
{
return obj;
}
}
catch (MySql.Data.MySqlClient.MySqlException e)
{
connection.Close();
throw e;
}
}
}
}
public object GetSingle(string SQLString, int Times)
{
using (MySqlConnection connection = new MySqlConnection(connectionString))
{
using (MySqlCommand cmd = new MySqlCommand(SQLString, connection))
{
try
{
connection.Open();
cmd.CommandTimeout = Times;
object obj = cmd.ExecuteScalar();
if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value)))
{
return null;
}
else
{
return obj;
}
}
catch (MySql.Data.MySqlClient.MySqlException e)
{
connection.Close();
throw e;
}
}
}
}
/// <summary>
/// 执行查询语句，返回MySqlDataReader ( 注意：调用该方法后，一定要对MySqlDataReader进行Close )
/// </summary>
/// <param name="strSQL">查询语句</param>
/// <returns>MySqlDataReader</returns>
public MySqlDataReader ExecuteReader(string strSQL)
{
MySqlConnection connection = new MySqlConnection(connectionString);
MySqlCommand cmd = new MySqlCommand(strSQL, connection);
try
{
connection.Open();
MySqlDataReader myReader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
return myReader;
}
catch (MySql.Data.MySqlClient.MySqlException e)
{
throw e;
}
}
/// <summary>
/// 执行查询语句，返回DataSet
/// </summary>
/// <param name="SQLString">查询语句</param>
/// <returns>DataSet</returns>
public DataSet Query(string SQLString)
{
using (MySqlConnection connection = new MySqlConnection(connectionString))
{
DataSet ds = new DataSet();
try
{
connection.Open();
MySqlDataAdapter command = new MySqlDataAdapter(SQLString, connection);
command.Fill(ds, "ds");
}
catch (MySql.Data.MySqlClient.MySqlException ex)
{
throw new Exception(ex.Message);
}
return ds;
}
}
public DataSet Query(string SQLString, int Times)
{
using (MySqlConnection connection = new MySqlConnection(connectionString))
{
DataSet ds = new DataSet();
try
{
connection.Open();
MySqlDataAdapter command = new MySqlDataAdapter(SQLString, connection);
command.SelectCommand.CommandTimeout = Times;
command.Fill(ds, "ds");
}
catch (MySql.Data.MySqlClient.MySqlException ex)
{
throw new Exception(ex.Message);
}
return ds;
}
}
#endregion
#region 执行带参数的SQL语句
/// <summary>
/// 执行SQL语句，返回影响的记录数
/// </summary>
/// <param name="SQLString">SQL语句</param>
/// <returns>影响的记录数</returns>
public int ExecuteSql(string SQLString, params MySqlParameter[] cmdParms)
{
using (MySqlConnection connection = new MySqlConnection(connectionString))
{
using (MySqlCommand cmd = new MySqlCommand())
{
try
{
PrepareCommand(cmd, connection, null, SQLString, cmdParms);
int rows = cmd.ExecuteNonQuery();
cmd.Parameters.Clear();
return rows;
}
catch (MySql.Data.MySqlClient.MySqlException e)
{
throw e;
}
}
}
}
/// <summary>
/// 执行一条计算查询结果语句，返回查询结果（object）。
/// </summary>
/// <param name="SQLString">计算查询结果语句</param>
/// <returns>查询结果（object）</returns>
public object GetSingle(string SQLString, params MySqlParameter[] cmdParms)
{
using (MySqlConnection connection = new MySqlConnection(connectionString))
{
using (MySqlCommand cmd = new MySqlCommand())
{
try
{
PrepareCommand(cmd, connection, null, SQLString, cmdParms);
object obj = cmd.ExecuteScalar();
cmd.Parameters.Clear();
if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value)))
{
return null;
}
else
{
return obj;
}
}
catch (MySql.Data.MySqlClient.MySqlException e)
{
throw e;
}
}
}
}
/// <summary>
/// 执行查询语句，返回MySqlDataReader ( 注意：调用该方法后，一定要对MySqlDataReader进行Close )
/// </summary>
/// <param name="strSQL">查询语句</param>
/// <returns>MySqlDataReader</returns>
public MySqlDataReader ExecuteReader(string SQLString, params MySqlParameter[] cmdParms)
{
MySqlConnection connection = new MySqlConnection(connectionString);
MySqlCommand cmd = new MySqlCommand();
try
{
PrepareCommand(cmd, connection, null, SQLString, cmdParms);
MySqlDataReader myReader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
cmd.Parameters.Clear();
return myReader;
}
catch (MySql.Data.MySqlClient.MySqlException e)
{
throw e;
}
// finally
// {
// cmd.Dispose();
// connection.Close();
// }
}
/// <summary>
/// 执行查询语句，返回DataSet
/// </summary>
/// <param name="SQLString">查询语句</param>
/// <returns>DataSet</returns>
public DataSet Query(string SQLString, params MySqlParameter[] cmdParms)
{
using (MySqlConnection connection = new MySqlConnection(connectionString))
{
MySqlCommand cmd = new MySqlCommand();
PrepareCommand(cmd, connection, null, SQLString, cmdParms);
using (MySqlDataAdapter da = new MySqlDataAdapter(cmd))
{
DataSet ds = new DataSet();
try
{
da.Fill(ds, "ds");
cmd.Parameters.Clear();
}
catch (MySql.Data.MySqlClient.MySqlException ex)
{
throw new Exception(ex.Message);
}
return ds;
}
}
}
private void PrepareCommand(MySqlCommand cmd, MySqlConnection conn, MySqlTransaction trans, string cmdText, MySqlParameter[] cmdParms)
{
if (conn.State != ConnectionState.Open)
conn.Open();
cmd.Connection = conn;
cmd.CommandText = cmdText;
if (trans != null)
cmd.Transaction = trans;
cmd.CommandType = CommandType.Text;//cmdType;
if (cmdParms != null)
{
foreach (MySqlParameter parameter in cmdParms)
{
if ((parameter.Direction == ParameterDirection.InputOutput || parameter.Direction == ParameterDirection.Input) &&
(parameter.Value == null))
{
parameter.Value = DBNull.Value;
}
cmd.Parameters.Add(parameter);
}
}
}
#endregion
}
}
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