c# - 从 sqlite 读取数据到 C# 然后到 sqlite

Question

可重现的例子:

sqlite db test3.s3db 有一个名为“MathRec”的表:

name score
Bill 2
Mary 3
John 3

代码:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Data;
using System.Data.SQLite;

namespace ConsoleApplication7

{
    class Program
    {
    static void Main(string[] args)
    {

        string fullPath = "C:\\Users\\Desktop\\dataset\\test3.s3db";
        SQLiteConnection conread = new SQLiteConnection("Data Source=" + fullPath);
        conread.Open();

        string selectSQL = "SELECT * FROM MathRec";
        SQLiteCommand selectCommand = new SQLiteCommand(selectSQL, conread);
        SQLiteDataReader dataReader = selectCommand.ExecuteReader();
        DataSet ds = new DataSet();
        DataTable dt = new DataTable("MathRec");
        dt.Load(dataReader);
        ds.Tables.Add(dt);



        // Create a table in the database to receive the information from the DataSet

        string fullPath2 = "C:\\Users\\\\Desktop\\dataset\\test4.s3db";
        SQLiteConnection conwrite = new SQLiteConnection("Data Source=" + fullPath2);
        conwrite.Open();
        SQLiteCommand cmd = new SQLiteCommand(conwrite);
        cmd.CommandText = "DROP TABLE IF EXISTS MathRec";
        cmd.ExecuteNonQuery();
        cmd.CommandText = "CREATE TABLE MathRec(name text , score integer)";
        cmd.ExecuteNonQuery();
        SQLiteDataAdapter adaptor = new SQLiteDataAdapter("SELECT * from MathRec", conwrite);
        adaptor.InsertCommand = new SQLiteCommand("INSERT INTO MathRec  VALUES(:name, :score)", conwrite);
        adaptor.InsertCommand.Parameters.Add("name", DbType.String, 0, "name");
        adaptor.InsertCommand.Parameters.Add("score", DbType.Int32, 0, "score");
        adaptor.Update(ds, "MathRec");



         }

    }
 }

问题:表 MathRec 在 test4.s3db 中创建，列名称为:name 和 socre，但该表是空的，没有插入任何记录。

需要帮助!

请不要问我为什么只是将一个数据库复制到另一个数据库，因为我正在为一个更大的项目测试代码的一部分，我将在未来的中间步骤对数据集进行计算。

谢谢!

---

为了简化问题:

这有效(使用数据表和适配器更新原始 sqlite 表):

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.SQLite;
using System.Data;

namespace ConsoleApplication7
{
    class Program
    {
        static void Main(string[] args)
        {
            string fullPath = "C:\\Users\\data\\test.db";
            SQLiteConnection conread = new SQLiteConnection("Data Source=" + fullPath);
            conread.Open();


        SQLiteDataAdapter DB = new SQLiteDataAdapter("SELECT speed, dist FROM Cars2", conread);
        DataSet DS = new DataSet();

        DB.Fill(DS, "NewCars");


        object[] rowVals = new object[2];
        rowVals[0] = 10;
        rowVals[1] = 20;
        DS.Tables["NewCars"].Rows.Add(rowVals);


        DB.InsertCommand = new SQLiteCommand("INSERT INTO Cars2 (speed, dist)  
                                 " + " VALUES (:speed,  :dist)", conread);
        DB.InsertCommand.Parameters.Add("speed", DbType.Double, 0, "speed");
        DB.InsertCommand.Parameters.Add("dist", DbType.Double, 20, "dist");
        DB.Update(DS, "NewCars");



        }
    }
}

这有效(从旧表创建一个新的 sqlite 表):

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.SQLite;
using System.Data;

namespace ConsoleApplication7
{
    class Program
    {
        static void Main(string[] args)
        {
            string fullPath = "C:\\Users\\data\\test.db";
            SQLiteConnection conread = new SQLiteConnection("Data Source=" + fullPath);
            conread.Open();


        SQLiteCommand cmd = new SQLiteCommand(conread);
        cmd.CommandText = "DROP TABLE IF EXISTS Cars";
        cmd.ExecuteNonQuery();
        cmd.CommandText = "CREATE TABLE Cars (speed REAL , dist REAL)";
        cmd.ExecuteNonQuery();
        cmd.CommandText = "INSERT INTO Cars SELECT * from DS";
        cmd.ExecuteNonQuery();
        cmd.Dispose();
        }
    }
}

但这是我想要的(使用数据表和适配器在 sqlite 中创建新表)并且不起作用:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.SQLite;
using System.Data;

namespace ConsoleApplication7
{
    class Program
    {
        static void Main(string[] args)
        {
            string fullPath = "C:\\Users\\data\\test.db";
            SQLiteConnection conread = new SQLiteConnection("Data Source=" + fullPath);
            conread.Open();
    SQLiteDataAdapter DB = new SQLiteDataAdapter("SELECT speed, dist FROM Cars2", conread);
    DataSet DS = new DataSet();

    DB.Fill(DS, "NewCars");


    object[] rowVals = new object[2];
    rowVals[0] = 10;
    rowVals[1] = 20;
    DS.Tables["NewCars"].Rows.Add(rowVals);


   SQLiteDataAdapter DB2 = new SQLiteDataAdapter("SELECT speed, dist FROM Cars3", conread);
    DB2.InsertCommand = new SQLiteCommand("INSERT INTO Cars3 (speed, dist)  
                        " + " VALUES (:speed,  :dist)", conread);
    DB2.InsertCommand.Parameters.Add("speed", DbType.Double, 0, "speed");
    DB2.InsertCommand.Parameters.Add("dist", DbType.Double, 20, "dist");
    DB2.Update(DS, "NewCars");


    }
}
}

请帮忙!!!

Answer 1

我找到了答案!

Adapter.Update 只能用于更新数据库中的原始表，不能用于将数据表保存到新表中。请参阅主题以获取答案:

C# Dataset to Access DB

干杯!