C#ADO.NET基礎一

簡介

使用SQLite進行講解

1.基礎類：

SQLiteConnection	連接數據庫
SQLiteCommand	執行命令（增，刪，改，查），或存儲過程
SQLiteDataReader	讀取查詢到的數據

2.SQLiteCommand講解

 

CommandType	獲取或設置Command對象要執行命令的類型
CommandText	獲取或設置要對數據庫執行的SQL語句或存儲過程名或表名
CommandTimeOut	獲取或設置在終止對執行命令的嘗試並生成錯誤之前的等待時間
Parameters	獲取Command對象需要使用的參數集合
ExecuteScalar	執行命令（查）返回數據中第一行第一列的值。
ExecuteNonQuery	執行命令（增，刪，改，查）
ExecuteReader	執行命令（查）返回查到的所有數據

 

一.下載SQLite庫

二.使用

1.連接

$@"Data Source={Application.StartupPath}\Test.db;Password=;Version=3;"

2.增

        private void btnAdd_Click(object sender, EventArgs e)
        {
            string name = "張三";
            int age = 19;

            using (SQLiteConnection conn = new SQLiteConnection(connStrl))
            {
                conn.Open();
                using (SQLiteCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = "insert into test(name,age) values(@name,@age);";
                    cmd.Parameters.AddWithValue("@name", name);
                    cmd.Parameters.AddWithValue("@age", age);
                    cmd.ExecuteNonQuery();
                }
                conn.Close();
            }
        }

 

3.刪

        private void btnDelete_Click(object sender, EventArgs e)
        {
            string name = "張三";

            try
            {
                using (SQLiteConnection conn = new SQLiteConnection(connStrl))
                {
                    conn.Open();
                    using (SQLiteCommand cmd = conn.CreateCommand())
                    {
                        cmd.CommandText = $"delete from test where name=@name";
                        cmd.Parameters.AddWithValue("@name", name);
                        cmd.ExecuteNonQuery();
                    }
                    conn.Close();
                }
            }
            catch (Exception)
            {
                throw;
            }
        }

 

4.改

        private void btnUpdate_Click(object sender, EventArgs e)
        {
            string nameOld = "張一";
            string nameNew = "張四";

            try
            {
                using (SQLiteConnection conn = new SQLiteConnection(connStrl))
                {
                    conn.Open();
                    using (SQLiteCommand cmd = conn.CreateCommand())
                    {
                        cmd.CommandText = $"update test set name=@nameNew where name=@nameOld";
                        cmd.Parameters.AddWithValue("@nameOld", nameOld);
                        cmd.Parameters.AddWithValue("@nameNew", nameNew);
                        cmd.ExecuteNonQuery();
                    }
                    conn.Close();
                }
            }
            catch (Exception)
            {
                throw;
            }
        }

 

5.查

        private void btnSelect_Click(object sender, EventArgs e)
        {
            textBox1.Text = "";
            try
            {
                using (SQLiteConnection conn = new SQLiteConnection(connStrl))
                {
                    conn.Open();
                    using (SQLiteCommand cmd = conn.CreateCommand())
                    {
                        cmd.CommandText = "select name,age from test";
                        using (SQLiteDataReader reader = cmd.ExecuteReader())
                        {
                            if (reader.HasRows)
                                while (reader.Read())
                                {
                                    string name = reader.GetString(0);
                                    int age = reader.GetInt32(1);

                                    textBox1.Text += $"name:{name} age:{age}\r\n";
                                }
                        }
                    }
                }
            }
            catch (Exception)
            {
                throw;
            }
        }