SQLite数据库操作类
首先：添加配置<add key="SQLString" value="~\demo.db"/>
/**************************************
* 作用：SQLLite Server操作实现
**************************************/
using System;
using System.Collections;
using System.Collections.Specialized;
using System.Data;
using System.Data.SQLite;//这个可以去网上下载
using System.Configuration;
public class SQLiteHelper
{
//数据库连接字符串(web.config来配置)，可以动态更改SQLString支持多数据库.
public static string connectionString = "Data Source=" + System.Web.HttpContext.Current.Server.MapPath(ConfigurationManager.AppSettings["SQLString"]);
public SQLiteHelper() { }
#region 公用方法
public static 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());
}
}
public static 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;
}
}
public static bool Exists(string strSql, params SQLiteParameter[] 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 static int ExecuteSql(string SQLString)
{
using (SQLiteConnection connection = new SQLiteConnection(connectionString))
{
using (SQLiteCommand cmd = new SQLiteCommand(SQLString, connection))
{
try
{
connection.Open();
int rows = cmd.ExecuteNonQuery();
return rows;
}
catch (System.Data.SQLite.SQLiteException E)
{
connection.Close();
throw new Exception(E.Message);
}
}
}
}
/// <summary>
/// 执行SQL语句，设置命令的执行等待时间
/// </summary>
/// <param name="SQLString"></param>
/// <param name="Times"></param>
/// <returns></returns>
public static int ExecuteSqlByTime(string SQLString, int Times)
{
using (SQLiteConnection connection = new SQLiteConnection(connectionString))
{
using (SQLiteCommand cmd = new SQLiteCommand(SQLString, connection))
{
try
{
connection.Open();
cmd.CommandTimeout = Times;
int rows = cmd.ExecuteNonQuery();
return rows;
}
catch (System.Data.SQLite.SQLiteException E)
{
connection.Close();
throw new Exception(E.Message);
}
}
}
}
/// <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 static void ExecuteSqlTran(ArrayList SQLStringList)
{
using (SQLiteConnection conn = new SQLiteConnection(connectionString))
{
conn.Open();
SQLiteCommand cmd = new SQLiteCommand();
cmd.Connection = conn;
SQLiteTransaction tx = conn.BeginTransaction();
cmd.Transaction = tx;
try
{
for (int n = 0; n < SQLStringList.Count; n++)
{
string strsql = SQLStringList[n].ToString();
if (strsql.Trim().Length > 1)
{
cmd.CommandText = strsql;
cmd.ExecuteNonQuery();
}
}
tx.Commit();
}
catch (System.Data.SQLite.SQLiteException E)
{
tx.Rollback();
throw new Exception(E.Message);
}
}
}
/// <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 static int ExecuteSql(string SQLString, string content)
{
using (SQLiteConnection connection = new SQLiteConnection(connectionString))
{
SQLiteCommand cmd = new SQLiteCommand(SQLString, connection);
SQLiteParameter myParameter = new SQLiteParameter("@content", DbType.String);
myParameter.Value = content;
cmd.Parameters.Add(myParameter);
try
{
connection.Open();
int rows = cmd.ExecuteNonQuery();
return rows;
}
catch (System.Data.SQLite.SQLiteException E)
{
throw new Exception(E.Message);
}
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 static object ExecuteSqlGet(string SQLString, string content)
{
using (SQLiteConnection connection = new SQLiteConnection(connectionString))
{
SQLiteCommand cmd = new SQLiteCommand(SQLString, connection);
SQLiteParameter myParameter = new SQLiteParameter("@content", DbType.String);
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 (System.Data.SQLite.SQLiteException E)
{
throw new Exception(E.Message);
}
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 static int ExecuteSqlInsertImg(string strSQL, byte[] fs)
{
using (SQLiteConnection connection = new SQLiteConnection(connectionString))
{
SQLiteCommand cmd = new SQLiteCommand(strSQL, connection);
SQLiteParameter myParameter = new SQLiteParameter("@fs", DbType.Binary);
myParameter.Value = fs;
cmd.Parameters.Add(myParameter);
try
{
connection.Open();
int rows = cmd.ExecuteNonQuery();
return rows;
}
catch (System.Data.SQLite.SQLiteException E)
{
throw new Exception(E.Message);
}
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 static object GetSingle(string SQLString)
{
using (SQLiteConnection connection = new SQLiteConnection(connectionString))
{
using (SQLiteCommand cmd = new SQLiteCommand(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 (System.Data.SQLite.SQLiteException e)
{
connection.Close();
throw new Exception(e.Message);
}
}
}
}
/// <summary>
/// 执行查询语句，返回SQLiteDataReader(使用该方法切记要手工关闭SQLiteDataReader和连接)
/// </summary>
/// <param name="strSQL">查询语句</param>
/// <returns>SQLiteDataReader</returns>
public static SQLiteDataReader ExecuteReader(string strSQL)
{
SQLiteConnection connection = new SQLiteConnection(connectionString);
SQLiteCommand cmd = new SQLiteCommand(strSQL, connection);
try
{
connection.Open();
SQLiteDataReader myReader = cmd.ExecuteReader();
return myReader;
}
catch (System.Data.SQLite.SQLiteException e)
{
throw new Exception(e.Message);
}
//finally //不能在此关闭，否则，返回的对象将无法使用
//{
// 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 static DataSet Query(string SQLString)
{
using (SQLiteConnection connection = new SQLiteConnection(connectionString))
{
DataSet ds = new DataSet();
try
{
connection.Open();
SQLiteDataAdapter command = new SQLiteDataAdapter(SQLString, connection);
command.Fill(ds, "ds");
}
catch (System.Data.SQLite.SQLiteException ex)
{
throw new Exception(ex.Message);
}
return ds;
}
}
public static DataSet Query(string SQLString, string TableName)
{
using (SQLiteConnection connection = new SQLiteConnection(connectionString))
{
DataSet ds = new DataSet();
try
{
connection.Open();
SQLiteDataAdapter command = new SQLiteDataAdapter(SQLString, connection);
command.Fill(ds, TableName);
}
catch (System.Data.SQLite.SQLiteException ex)
{
throw new Exception(ex.Message);
}
return ds;
}
}
/// <summary>
/// 执行查询语句，返回DataSet,设置命令的执行等待时间
/// </summary>
/// <param name="SQLString"></param>
/// <param name="Times"></param>
/// <returns></returns>
public static DataSet Query(string SQLString, int Times)
{
using (SQLiteConnection connection = new SQLiteConnection(connectionString))
{
DataSet ds = new DataSet();
try
{
connection.Open();
SQLiteDataAdapter command = new SQLiteDataAdapter(SQLString, connection);
command.SelectCommand.CommandTimeout = Times;
command.Fill(ds, "ds");
}
catch (System.Data.SQLite.SQLiteException 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 static int ExecuteSql(string SQLString, params SQLiteParameter[] cmdParms)
{
using (SQLiteConnection connection = new SQLiteConnection(connectionString))
{
using (SQLiteCommand cmd = new SQLiteCommand())
{
try
{
PrepareCommand(cmd, connection, null, SQLString, cmdParms);
int rows = cmd.ExecuteNonQuery();
cmd.Parameters.Clear();
return rows;
}
catch (System.Data.SQLite.SQLiteException E)
{
throw new Exception(E.Message);
}
}
}
}
/// <summary>
/// 执行多条SQL语句，实现数据库事务。
/// </summary>
/// <param name="SQLStringList">SQL语句的哈希表（key为sql语句，value是该语句的SQLiteParameter[]）</param>
public static void ExecuteSqlTran(Hashtable SQLStringList)
{
using (SQLiteConnection conn = new SQLiteConnection(connectionString))
{
conn.Open();
using (SQLiteTransaction trans = conn.BeginTransaction())
{
SQLiteCommand cmd = new SQLiteCommand();
try
{
//循环
foreach (DictionaryEntry myDE in SQLStringList)
{
string cmdText = myDE.Key.ToString();
SQLiteParameter[] cmdParms = (SQLiteParameter[]) myDE.Value;
PrepareCommand(cmd, conn, trans, cmdText, cmdParms);
int val = cmd.ExecuteNonQuery();
cmd.Parameters.Clear();
trans.Commit();
}
}
catch
{
trans.Rollback();
throw;
}
}
}
}
/// <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 static object GetSingle(string SQLString, params SQLiteParameter[] cmdParms)
{
using (SQLiteConnection connection = new SQLiteConnection(connectionString))
{
using (SQLiteCommand cmd = new SQLiteCommand())
{
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 (System.Data.SQLite.SQLiteException e)
{
throw new Exception(e.Message);
}
}
}
}
/// <summary>
/// 执行查询语句，返回SQLiteDataReader (使用该方法切记要手工关闭SQLiteDataReader和连接)
/// </summary>
/// <param name="strSQL">查询语句</param>
/// <returns>SQLiteDataReader</returns>
public static SQLiteDataReader ExecuteReader(string SQLString, params SQLiteParameter[] cmdParms)
{
SQLiteConnection connection = new SQLiteConnection(connectionString);
SQLiteCommand cmd = new SQLiteCommand();
try
{
PrepareCommand(cmd, connection, null, SQLString, cmdParms);
SQLiteDataReader myReader = cmd.ExecuteReader();
cmd.Parameters.Clear();
return myReader;
}
catch (System.Data.SQLite.SQLiteException e)
{
throw new Exception(e.Message);
}
//finally //不能在此关闭，否则，返回的对象将无法使用
//{
// 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 static DataSet Query(string SQLString, params SQLiteParameter[] cmdParms)
{
using (SQLiteConnection connection = new SQLiteConnection(connectionString))
{
SQLiteCommand cmd = new SQLiteCommand();
PrepareCommand(cmd, connection, null, SQLString, cmdParms);
using (SQLiteDataAdapter da = new SQLiteDataAdapter(cmd))
{
DataSet ds = new DataSet();
try
{
da.Fill(ds, "ds");
cmd.Parameters.Clear();
}
catch (System.Data.SQLite.SQLiteException ex)
{
throw new Exception(ex.Message);
}
return ds;
}
}
}
public static void PrepareCommand(SQLiteCommand cmd, SQLiteConnection conn, SQLiteTransaction trans, string cmdText, SQLiteParameter[] 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 (SQLiteParameter parameter in cmdParms)
{
if ((parameter.Direction == ParameterDirection.InputOutput || parameter.Direction == ParameterDirection.Input) &&
(parameter.Value == null))
{
parameter.Value = DBNull.Value;
}
cmd.Parameters.Add(parameter);
}
}
}
#endregion
#region 参数转换
/// <summary>
/// 放回一个SQLiteParameter
/// </summary>
/// <param name="name">参数名字</param>
/// <param name="type">参数类型</param>
/// <param name="size">参数大小</param>
/// <param name="value">参数值</param>
/// <returns>SQLiteParameter的值</returns>
public static SQLiteParameter MakeSQLiteParameter(string name, DbType type, int size, object value)
{
SQLiteParameter parm = new SQLiteParameter(name, type, size);
parm.Value = value;
return parm;
}
public static SQLiteParameter MakeSQLiteParameter(string name, DbType type, object value)
{
SQLiteParameter parm = new SQLiteParameter(name, type);
parm.Value = value;
return parm;
}
#endregion
}
调用方法
/// <summary>
/// 判断用户是否存在
/// </summary>
/// <param name="name">用户名称</param>
/// <returns></returns>
public bool UserExists(string name)
{
StringBuilder strSql = new StringBuilder();
strSql.Append("select count(*) n from Users");
strSql.Append(" where UserName=@UserName ");
SQLiteParameter[] parameters = {
SQLiteHelper.MakeSQLiteParameter("@UserName", DbType.String,30,name)};
return SQLiteHelper.Exists(strSql.ToString(), parameters);
}
/// <summary>
/// 增加一个用户
/// </summary>
/// <param name="name">用户名</param>
/// <param name="pwd">密码</param>
/// <returns></returns>
public int CreateUser(string name, string pwd)
{
int ret = 0;
if (!UserExists(name))
{
StringBuilder strSql = new StringBuilder();
strSql.Append("insert into t_UserGroup(");
strSql.Append("UserName,Password)");
strSql.Append(" values (");
strSql.Append("@UserName,@Password)");
SQLiteParameter[] parameters = {
SQLiteHelper.MakeSQLiteParameter("@UserName", DbType.String,30,name),
SQLiteHelper.MakeSQLiteParameter("@Password", DbType.String,128,pwd)
};
if (SQLiteHelper.ExecuteSql(strSql.ToString(), parameters) >= 1)
{
ret = 1;
}
}
else
{
ret = 2;
}
return ret;
}
/// <summary>
/// 更新一条数据
/// </summary>
/// <param name="model">用户分组实体类</param>
/// <returns></returns>
public bool UpdateUser(int id, string name, string pwd)
{
StringBuilder strSql = new StringBuilder();
strSql.Append("update Users set ");
strSql.Append("UserName=@UserName,");
strSql.Append("Password=@Password");
strSql.Append(" where UserID=@UserID");
SQLiteParameter[] parameters = {
SQLiteHelper.MakeSQLiteParameter("@UserID", DbType.Int32,11,id),
SQLiteHelper.MakeSQLiteParameter("@UserName", DbType.String,30,name),
SQLiteHelper.MakeSQLiteParameter("@Password", DbType.String,128,pwd)};
if (SQLiteHelper.ExecuteSql(strSql.ToString(), parameters) >= 1)
{
return true;
}
else
{
return false;
}
}
/// <summary>
/// 删除用户
/// </summary>
/// <param name="ID">用户ID</param>
/// <returns></returns>
public int DeleteUser(int id)
{
int ret = 0;
string strSql3 = "delete from Users where UserID=@UserID";
SQLiteParameter[] parameters = {
SQLiteHelper.MakeSQLiteParameter("@UserID", DbType.Int32,4,id)};
if (SQLiteHelper.ExecuteSql(strSql3, parameters) >= 1)
{
ret = 1;
}
else
{
ret = 0;
}
return ret;
}
/// <summary>
/// 获得用户分组数据列表
/// </summary>
/// <param name="strWhere">Where条件</param>
/// <returns></returns>
public DataSet GetUserList(string strWhere)
{
StringBuilder strSql = new StringBuilder();
strSql.Append("select * FROM Users ");
if (strWhere.Trim() != "")
{
strSql.Append(" where " + strWhere);
}
strSql.Append(" order by UserID desc");
return SQLiteHelper.Query(strSql.ToString());
}
注意事项
1. @@IDENTITY LAST_INSERT_ROWID()
2. SELECT cn = COUNT(*) FROM ... SELECT COUNT(*) cn FROM ...
3. LIMIT startIndex,itemCn 这儿的startIndex是从0开始的，而ROW_NUMBER()是从1开始的
4. sqlite中没有SELECT TOP,用LIMIT即可
5. SQLite自增字段，如果在事务中插入数据失败，并不会占用增长后的id，而sql server中对应的id将无效
6. SQLite中没有GETDATE日期函数，在类中加入参数如下DbType.DateTime,DateTime.Now.ToString("s")
7. SQLite支持REPLACE INTO语法,sql server 2008中支持merge to