C# 数据库查询执行

我在C#中有一个应用程序，数据库是sqlite（.db3）。我有两个函数

String sConnectionString = "Data Source=mydb.db3;Version=3;Password=123456;";
private void longitudinalProfileToolStripMenuItem_Click(object sender, EventArgs e)
{
    saveProject(iProjectID);
    computeArea(iProjectID);
}

public int saveProject(iProjectID)
{
    SQLiteCommand sqlite_cmd;
    SQLiteCommand sqlite_cmd_PostWork;
    SQLiteCommand sqlite_cmd_Design;
    sqlite_conn = new SQLiteConnection(sConnectionString);
    sqlite_cmd.CommandText = "Delete from prework where pid = " + iProjectID + ";";
    sqlite_cmd.ExecuteNonQuery();
    sqlite_cmd.CommandText = "Insert into prework (pid, chainage, date) values (" + iProjectID + "," + fChainagePostwork + ",'" + dateTimePicker1.Value.Date.ToString("yyyy-MM-dd") + "');";
    sqlite_cmd.ExecuteNonQuery();
    sqlite_conn.Close();
return 1;
}

public int computeArea(iProjectID)
{
    SQLiteCommand sqlite_cmd;
    SQLiteCommand sqlite_cmd_PostWork;
    SQLiteCommand sqlite_cmd_Design;
    sqlite_conn = new SQLiteConnection(sConnectionString);
    sqlite_cmd.CommandText = "Delete from postwork where pid = " + iProjectID + ";";
    sqlite_cmd.ExecuteNonQuery();
    sqlite_cmd.CommandText = "Insert into postwork (pid, chainage, date) values (" + iProjectID + "," + fChainagePostwork + ",'" + dateTimePicker1.Value.Date.ToString("yyyy-MM-dd") + "');";
    sqlite_cmd.ExecuteNonQuery();
    sqlite_conn.Close();
return 1;
}

saveProject（）函数工作正常。 但在computeArea（）函数中，查询不会显示任何错误，但数据库/表不会更新/插入/删除

如果我第二次调用纵向profiletoolstripmenuitem_Click（objectsender，EventArgs e），那么它可以正常工作

但在前一次，它工作正常。

---

有什么问题吗？

您可以像这样使用“使用块”

String sConnectionString = "Data Source=mydb.db3;Version=3;Password=123456;";
private void longitudinalProfileToolStripMenuItem_Click(object sender, EventArgs e)
{
    saveProject(iProjectID);
    computeArea(iProjectID);
}

saveProject(iProjectID)
{
    SQLiteCommand sqlite_cmd;
    SQLiteCommand sqlite_cmd_PostWork;
    SQLiteCommand sqlite_cmd_Design;
    using (sqlite_conn = new SQLiteConnection(sConnectionString))
    {
        sqlite_conn.Open();
        sqlite_cmd.CommandText = "Delete from prework where pid = " + iProjectID + ";";
        sqlite_cmd.ExecuteNonQuery();
        sqlite_cmd.CommandText = "Insert into prework (pid, chainage, date) values (" + iProjectID + "," + fChainagePostwork + ",'" + dateTimePicker1.Value.Date.ToString("yyyy-MM-dd") + "');";
        sqlite_cmd.ExecuteNonQuery();
    }
}

computeArea(iProjectID)
{
    SQLiteCommand sqlite_cmd;
    SQLiteCommand sqlite_cmd_PostWork;
    SQLiteCommand sqlite_cmd_Design;

    using (sqlite_conn = new SQLiteConnection(sConnectionString))
    {
        sqlite_conn.Open();
        sqlite_cmd.CommandText = "Delete from postwork where pid = " + iProjectID + ";";
        sqlite_cmd.ExecuteNonQuery();
        sqlite_cmd.CommandText = "Insert into postwork (pid, chainage, date) values (" + iProjectID + "," + fChainagePostwork + ",'" + dateTimePicker1.Value.Date.ToString("yyyy-MM-dd") + "');";
        sqlite_cmd.ExecuteNonQuery();
    }
}

---

这两个表的模式是什么？您正在使用字符串连接，它除了使您暴露于SQL注入攻击之外，还将由于类型转换错误而中断。如果一个表需要一个字符串，而另一个表需要一个浮点，那么如果您试图输入一个带有意外小数分隔符的字符串，则第二个表将失败。顺便说一句，您的代码不是有效的C代码

computeArea（IProjectd）

不是有效的函数声明。实际编译的Post代码，包括任何可能隐藏错误的异常处理代码。如果我单独调用第二个函数，它实际上可以正常工作。如果我以和问题相同的方式调用，那么它不会显示任何错误@PanagiotisKanavosI添加了“sqlite_conn.Open（）；”