Question

我正在尝试使用VarChar列的字符串变量向表中添加记录。我想在下一个递增的ID下插入我给它的值。但是，当我尝试运行代码时，我不断收到“没有这样的列存在”的SQL错误。没有详细说明错误发生的位置，所以我有点陷入困境。那么如何将记录插入表中呢？

这是我的代码

using UnityEngine;
using Mono.Data.Sqlite;
using System.Data;
using UnityEngine.UI;
using System.Collections;

public class AddQuery : MonoBehaviour {

    public Text cipher;
    public Text initialMessage;
    public Text encryptedMessage;

    private string _constr = "URI=file:previousMessages.db";
    private IDbConnection _dbc;
    private IDbCommand _dbcm;
    private IDataReader _dbr;


public void AddSQL() {
    string _cipher = cipher.text;
    string _initialMessage = initialMessage.text;
    string _encryptedMessage = encryptedMessage.text;

    _dbc = new SqliteConnection(_constr);
    _dbc.Open();

    _dbcm = _dbc.CreateCommand();
    _dbcm.CommandText = "CREATE TABLE IF NOT EXISTS previousMessages (ID    INTEGER NOT NULL PRIMARY KEY , Cipher   VARCHAR(5000) NOT NULL, InitialMessage  VARCHAR(5000) NOT NULL,EncryptedMessage TEXT NOT NULL)";
    _dbr = _dbcm.ExecuteReader();
    _dbr.Close();

    _dbcm.CommandText = "INSERT INTO previousMessages ( Cipher, InitialMessage, EncryptedMessage) VALUES ( "+_cipher+", "+_initialMessage+", "+_encryptedMessage+")";
    _dbr = _dbcm.ExecuteReader();
    _dbr.Close();

    _dbcm.CommandText = "SELECT FROM previousMessages (Cipher, InitialMessage, EncryptedMessage) VALUES ( " + _cipher + ", " + _initialMessage + ", " + _encryptedMessage + ")";
    _dbr = _dbcm.ExecuteReader();

    while (_dbr.Read())
    {
        Debug.Log("Cipher: " + _dbr["Cipher"] + "\t Initial: " + _dbr["InitialMessage"]);
    }

}

}

Answer 1

如果你遵循OOP，你的生活会更简单。我的意思是你宁愿让方法只做一件事;或者如果它做了许多事情而不是使它成为一个调用其他方法的列表，每个方法只做一件事。据说你的AddSQL()分解为：

public void AddSQL() {
    string _cipher = cipher.text;
    string _initialMessage = initialMessage.text;
    string _encryptedMessage = encryptedMessage.text;

    OpenConnection();
    ExecuteCreateCommand();
    InsertCommand(_cipher, _initialMessage, _encryptedMessage);
    ReadStuff(_cipher, _initialMessage, _encryptedMessage);
    DebugRead();

}

void OpenConnection(){
    _dbc = new SqliteConnection(_constr);
    _dbc.Open();
}

void ExecuteCreateCommand(){
    _dbcm = _dbc.CreateCommand();
    _dbcm.CommandText = "CREATE TABLE IF NOT EXISTS previousMessages (ID    INTEGER NOT NULL PRIMARY KEY , Cipher   VARCHAR(5000) NOT NULL, InitialMessage  VARCHAR(5000) NOT NULL,EncryptedMessage TEXT NOT NULL)";
    _dbr = _dbcm.ExecuteReader();
    _dbr.Close();
}

void InsertCommand(string _cipher, string _initialMessage, string _encryptedMessage){
    _dbcm.CommandText = "INSERT INTO previousMessages ( Cipher, InitialMessage, EncryptedMessage) VALUES ( "+_cipher+", "+_initialMessage+", "+_encryptedMessage+")";
    _dbr = _dbcm.ExecuteReader();
    _dbr.Close();
}

void ReadStuff(string _cipher, string _initialMessage, string _encryptedMessage){
    _dbcm.CommandText = "SELECT FROM previousMessages (Cipher, InitialMessage, EncryptedMessage) VALUES ( " + _cipher + ", " + _initialMessage + ", " + _encryptedMessage + ")";
    _dbr = _dbcm.ExecuteReader();
}

void DebugRead(){
    while (_dbr.Read())
    {
        Debug.Log("Cipher: " + _dbr["Cipher"] + "\t Initial: " + _dbr["InitialMessage"]);
    }
}

现在在AddSQL()注释所有方法调用并逐个取消注释，以查看哪个查询引发异常。

如何使用SQLite将记录插入Unity的表中？

1 个答案: