簡單SQLite 數據庫操作Demo

public class DbHelperSQLite
{
public string connectionString = "Data Source=" + AppDomain.CurrentDomain.BaseDirectory + @"WIP.db;Version=3;";

public event EventHandler<SQLiteMessageEventArg> SQLiteMessageEvent;

public DbHelperSQLite()
{ }

/// <summary>
/// 執行單條SQL語句，返回值(bool)
/// </summary>
/// <param name="SQLString"></param>
/// <returns></returns>
public bool ExecuteSql(string SQLString)
{
var eventHandle = SQLiteMessageEvent;
string msg = "";

using (SQLiteConnection connection = new SQLiteConnection(connectionString))
{
using (SQLiteCommand cmd = new SQLiteCommand(SQLString, connection))
{
try
{
connection.Open();
cmd.ExecuteNonQuery();
msg = "SQL Command: " + SQLString + " Excute Success!";
if (eventHandle != null)
{
eventHandle(null, new SQLiteMessageEventArg(SQLiteMessageType.Msg, msg, SQLString));
}
return true;
}
catch (SQLiteException ex)
{
msg = "Execute SQL Error Message: " + ex.Message;
if (eventHandle != null)
{
eventHandle(null, new SQLiteMessageEventArg(SQLiteMessageType.ErrorSql, msg, SQLString));
}
return false;
}
finally
{
connection.Close();
cmd.Dispose();
}
}
}
}

/// <summary>
/// 獲取最大值，返回值(int)
/// </summary>
/// <param name="FieldName">欄位名稱</param>
/// <param name="TableName">表名稱</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;
}
return int.Parse(obj.ToString());
}

/// <summary>
/// 單值查詢，返回查詢結果(Object)
/// </summary>
/// <param name="SQLString"></param>
/// <returns></returns>
public object GetSingle(string SQLString)
{
var eventHandle = SQLiteMessageEvent;
string msg = "";

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)))
{
msg = "WARN : SQL Command Return null! [ " + SQLString + "]";
if (eventHandle != null)
{
eventHandle(null, new SQLiteMessageEventArg(SQLiteMessageType.Msg, msg, SQLString));
}
return null;
}
else
{
msg = "SQL Command: " + SQLString + " Excute Success!";
if (eventHandle != null)
{
eventHandle(null, new SQLiteMessageEventArg(SQLiteMessageType.Msg, msg, SQLString));
}
return obj;
}
}
catch (SQLiteException e)
{
msg = "Execute SQL Error Message: " + e.Message;
if (eventHandle != null)
{
eventHandle(null, new SQLiteMessageEventArg(SQLiteMessageType.ErrorSql, msg, SQLString));
}
connection.Close();
return null;
}
finally
{
connection.Close();
cmd.Dispose();
}

}
}
}

/// <summary>
/// 執行多條SQL語句，實現數據庫事務
/// </summary>
/// <param name="SQLStringList"></param>
public void ExcuteSqlTran(ArrayList SQLStringList)
{
var eventHandle = SQLiteMessageEvent;
string msg = "";
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
.ToString();
if (strsql.Trim().Length > 1)
{
cmd.CommandText = strsql;
cmd.ExecuteNonQuery();
msg = "SQL Command: " + strsql + " Excute Success!";
if (eventHandle != null)
{
eventHandle(null, new SQLiteMessageEventArg(SQLiteMessageType.Msg, msg, strsql));
}
}
else
{
msg = "Execute SQL Error Message: strsql.Trim().Length=" + strsql.Trim().Length.ToString();
if (eventHandle != null)
{
eventHandle(null, new SQLiteMessageEventArg(SQLiteMessageType.ErrorSql, msg, strsql));
}
}
}
tx.Commit();
}
catch (SQLiteException ex)
{
tx.Rollback();
msg = "Execute SQL Error Message: " + ex.Message;
if (eventHandle != null)
{
eventHandle(null, new SQLiteMessageEventArg(SQLiteMessageType.ErrorSql, msg, "[ExcuteSqlTran]"));
}
}
finally
{
conn.Close();
cmd.Dispose();
}
}
}

/// <summary>
/// 執行單條SQL語句，返回值(DataTable)
/// </summary>
/// <param name="SQLString"></param>
/// <returns></returns>
public DataTable SelectUse(string SQLString)
{
var eventHandle = SQLiteMessageEvent;
string msg = "";

SQLiteCommand cmd = null;
SQLiteDataAdapter oda = null;
SQLiteConnection connection = null;
DataTable dt;
try
{
connection = new SQLiteConnection(connectionString);
cmd = new SQLiteCommand(SQLString, connection);
connection.Open();
dt = new DataTable();
cmd.Transaction = connection.BeginTransaction();
oda = new SQLiteDataAdapter(cmd);
oda.Fill(dt);

msg = "SQL Command: " + SQLString + " Excute Success!";
if (eventHandle != null)
{
eventHandle(null, new SQLiteMessageEventArg(SQLiteMessageType.Msg, msg, SQLString));
}

return dt;

}
catch (SQLiteException ex)
{
msg = "Execute SQL Error Message: " + ex.Message;
if (eventHandle != null)
{
eventHandle(null, new SQLiteMessageEventArg(SQLiteMessageType.ErrorSql, msg, SQLString));
}
return null;
}
finally
{
connection.Close();
cmd.Dispose();
oda.Dispose();
}
}

/// <summary>
/// 測試DB連接
/// </summary>
/// <returns></returns>
public bool ConnectConfirm()
{
var sqlStr = "select 1+1 from A"; //A是SQLite DB中的表
var result = SelectUse(sqlStr);
if (result != null)
{
if (result.Rows.Count == 0)
{
return false;
}
return true;
}
else
{
return false;
}
}

}

/// <summary>
/// 回復事件
/// </summary>
public class SQLiteMessageEventArg:EventArgs
{
public SQLiteMessageType EventId { get; private set; }

public string EventData{get;private set;}

public string SqlCommand { get; private set; }

public SQLiteMessageEventArg(SQLiteMessageType type, string data, string StrSql)
{
EventId = type;
EventData = data;
SqlCommand = StrSql;
}
}

public enum SQLiteMessageType
{
None = 0,
Info = 1,
Msg = 2,
Error = 3,
ErrorSql = 4,
ConnectBroken = 5,
Others = 9
}

//=======================主界面================================
static void Main(string[] args)
{
bHelperSQLite _DB = new DbHelperSQLite();
_DB.SQLiteMessageEvent += new EventHandler<SQLiteMessageEventArg>(_DB_SQLiteMessageEvent);
string _sql = "select Seq,cstid,D_Time,flag from w_CSTinfo";
DataTable _dt=_DB.SelectUse(_sql);
... ...
}

/// <summary>
/// DB執行對象返回事件
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
void _DB_SQLiteMessageEvent(object sender, SQLiteMessageEventArg e)
{
switch (e.EventId)
{
case SQLiteMessageType.Msg:
MessageBox.Show(e.EventData);
break;
case SQLiteMessageType.Error:
MessageBox.Show(e.EventData + ", SQL: " + e.SqlCommand);
break;
case SQLiteMessageType.ErrorSql:
MessageBox.Show(e.EventData);
break;
default:
break;
}
}