Question

我试图从文本文件创建动态插入语句，只有SQLite。

到目前为止，我所做的是创建带有必要参数的SQL查询，在运行时添加这些参数，并尝试选择。

但是当我尝试cmd.ExecuteNonQuery();

时，我在try块中遇到错误

捕获异常：SQL逻辑错误或缺少数据库接近＆＃34; @ 0＆＃34;：语法错误

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

namespace TestApp

    class Program
    {
        static void Main(string[] args)
        {
           //To store the index and column name in the file
           Dictionary<int, string> Columns = new Dictionary<int, string>();
           char[] delimiterChars = { '\t' };
            string createQuery = @" create table if not exists products(id integer not null primary key, name text);
                                insert into products (name) values ('A');
                                insert into products (name) values ('B');
                                insert into products (name) values ('C');
                                insert into products (name) values ('D');
                                insert into products (name) values ('E');
                                insert into products (name) values ('F');
                                insert into products (name) values ('G');
                                create table if not exists orders(id integer, dt datetime, product_id integer, amount real);"; 
        System.Data.SQLite.SQLiteConnection.CreateFile("myDB.db3");
        using (System.Data.SQLite.SQLiteConnection conn = new System.Data.SQLite.SQLiteConnection("data source=myDB.db3")){
            using (System.Data.SQLite.SQLiteCommand cmd = new System.Data.SQLite.SQLiteCommand(conn)){
                conn.Open();
                cmd.CommandText = createQuery;
                cmd.ExecuteNonQuery();
                string[] lines = System.IO.File.ReadAllLines(Directory.GetCurrentDirectory() + @"../../../App_Data/import.txt");
                cmd.CommandText = "INSERT INTO orders (";
                // Identify the column order from first row of the import file
                string[] elements = lines[0].Split(delimiterChars);
                for (int i = 0; i < elements.Length; i++)
                {
                    Columns[i] = elements[i];
                    cmd.CommandText = cmd.CommandText + "@COLUMN" + i + ", ";
                    cmd.Parameters.AddWithValue("@COLUMN" + i, Columns[i]);
                    System.Console.WriteLine(i + " : " + Columns[i]);

                }
                cmd.CommandText = cmd.CommandText.Remove(cmd.CommandText.Length - 2);
                cmd.CommandText = cmd.CommandText + ") VALUES (";
                string temp = cmd.CommandText;
                System.Console.WriteLine(cmd.CommandText);
                System.Console.WriteLine("Contents of Import File.txt = ");
                for (int i = 1; i < lines.Length; i++)
                {
                    cmd.CommandText = temp;
                    elements = lines[i].Split(delimiterChars);
                    for (int j = 0; j < elements.Length; j++)
                    {
                        cmd.CommandText = cmd.CommandText + "@VALUE" + j + ", ";
                        cmd.Parameters.AddWithValue("@VALUE" + j, elements[j]);
                    }
                    cmd.CommandText = cmd.CommandText.Remove(cmd.CommandText.Length - 2);
                    cmd.CommandText = cmd.CommandText + ")";
                    try
                    {
                        cmd.ExecuteNonQuery();
                    }
                    catch (Exception ex)
                    {
                        Console.WriteLine("Caught exception: " + ex.Message);
                    }

                    Console.WriteLine(cmd.CommandText);
                    Console.WriteLine(lines[i]);
                }

                cmd.CommandText = "Select * from orders";
                cmd.ExecuteNonQuery();
                using (System.Data.SQLite.SQLiteDataReader reader = cmd.ExecuteReader()){
                    while (reader.Read())
                    {
                        Console.WriteLine(reader["ID"] + " | " + reader["dt"] + " | " + reader["product_id"] + " | " + reader["amount"]);
                    }
                    conn.Close();
                }
            }
        }
        Console.WriteLine("Press any key to exit.");
        Console.ReadLine();
    }
}
}

我不确定我做错了什么？

import.txt文件由

组成

id  dt  amount  product_id
1   2017-02-01T10:01:12 343.33  1
2   2017-02-01T10:02:12 12  2
3   2017-03-01T10:03:12 344.3   1
4   2017-04-01T10:04:12 12  3
5   2017-05-01T10:05:12 66.5    1
6   2017-06-01T10:06:12 4

所有项目除以TAB

Answer 1

列名称循环没用，因为您已经知道第一行执行的CREATE TABLE ORDERS命令中的列名。
顺便说一句，您不能使用参数来表示列的名称在我所知的任何类型的数据库系统中都不允许这样做。

您可以安全地删除它，但请注意您已错误地声明了列顺序。在CREATE TABLE中你有

create table if not exists orders(
id integer, dt datetime, product_id integer, amount real

在文件中 product_id 是最后一列。所以你需要调整你的CREATE TABLE到你的文件

create table if not exists orders(
id integer, dt datetime, amount real, product_id integer;

接下来你的插入循环代码可以用这种方式重写（在解释时忽略可变数量的参数）

string baseQuery = "INSERT INTO orders (id, dt, amount, product_id ) VALUES(";
string[] lines = System.IO.File.ReadAllLines(@"e:\temp\orders.txt");

// Skip the first line
for (int i = 1; i < lines.Length; i++)
{
    string[] elements = lines[i].Split(delimiterChars);

    // Keep the parameter names in a list to get an easy way to 
    // concatenate them all together at the end of the loop
    List<string> text = new List<string>();
    for (int j = 0; j < elements.Length; j++)
    {
        text.Add("@VALUE" + j);
        cmd.Parameters.AddWithValue("@VALUE" + j, elements[j]);
    }
    // Create the command text in a single shot
    cmd.CommandText = baseQuery + string.Join(",", text) + ")";
    try
    {
        cmd.ExecuteNonQuery();
    }
    catch (Exception ex)
    {
        Console.WriteLine("Caught exception: " + ex.Message);
    }
}

考虑将您的数据库代码包含在这样的事务中，如下面由Alexander Petrov发布的链接所示

using (System.Data.SQLite.SQLiteConnection conn = new System.Data.SQLite.SQLiteConnection("data source=myDB.db3"))
using (System.Data.SQLite.SQLiteCommand cmd = new System.Data.SQLite.SQLiteCommand(conn))
{
     conn.Open();
     using(SQLiteTransaction tr = conn.BeginTransaction())
     {
         cmd.Transaction = tr;
         .....
         for(....)
         {
             .....
         }
         tr.Commit();
     }
}

从文本文件动态插入SQLite

1 个答案: