C# Sqlite 参数 Working/Not 在不同页面工作

Question

第一次发帖。我正在为我的一个小项目尝试 sqlite，我遇到了一些非常奇怪的事情。问题似乎出在参数上，但我不明白。也许这里有人可以向我解释为什么它在某些地方有效但在另一个地方无效。

就是这样：在此代码中一切正常：

    public void SaveObject(PlayerCharacter playerCharacter)
    {
        SQLiteConnection sqliteConnection = new SQLiteConnection(ConnectionString.Connection);
        sqliteConnection.Open();

        String query = String.Empty;

        switch (playerCharacter.InternalState)
        {
            case InternalStates.New:
                query = "INSERT INTO PlayerCharacters(Id, Name, ArmorClass, InitiativeBonus) VALUES (@Id, @Name, @ArmorClass, @InitiativeBonus)";
                break;

            case InternalStates.Modified:
                query = @"  UPDATE PlayerCharacters
                            SET Name = @Name,
                                ArmorClass = @ArmorClass,
                                InitiativeBonus = @InitiativeBonus
                            WHERE Id = @Id";
                break;

            case InternalStates.Deleted:
                //To maybe implement in the future
                break;
        }

        List<SQLiteParameter> parameters = new List<SQLiteParameter>()
        {
            new SQLiteParameter("@Id", playerCharacter.Id),
            new SQLiteParameter("@Name", playerCharacter.Name),
            new SQLiteParameter("@ArmorClass", playerCharacter.ArmorClass),
            new SQLiteParameter("@InitiativeBonus", playerCharacter.InitiativeBonus)
        };

        SQLiteCommand command = new SQLiteCommand(query, sqliteConnection);
        command.Parameters.AddRange(parameters.ToArray());

        command.ExecuteNonQuery();

        playerCharacter.SetInternalState(InternalStates.UnModified, true);

        sqliteConnection.Close();
    }

在这里我试图找出问题所在。当我删除参数 Id 和 Where 子句时，所有内容都会按应有的方式更新，但是当我尝试使用参数时，它永远找不到要更新的行：

    public void SaveObject(Monster monster)
    {
        SQLiteConnection sqliteConnection = new SQLiteConnection(ConnectionString.Connection);
        sqliteConnection.Open();

        String query = String.Empty;

        switch (monster.InternalState)
        {
            case InternalStates.New:
                query = @"  INSERT INTO Monsters(Id,
                                                Name,
                                                Size,
                                                Type,
                                                Subtype,
                                                Alignment,
                                                ArmorClass,
                                                HitPoints,
                                                HitDice,
                                                Speed,
                                                DamageVulnerabilities,
                                                DamageResistances,
                                                DamageImmunities,
                                                ConditionImmunities,
                                                Senses,
                                                Languages,
                                                ChallengeRating) 
                            VALUES (@Id,
                                    @Name,
                                    @Size,
                                    @Type,
                                    @Subtype,
                                    @Alignment,       
                                    @ArmorClass,
                                    @HitPoints,
                                    @HitDice,
                                    @Speed,
                                    @DamageVulnerabilities,
                                    @DamageResistances,
                                    @DamageImmunities,
                                    @ConditionImmunities,
                                    @Senses,
                                    @Languages,
                                    @ChallengeRating)";
                break;

            case InternalStates.Modified:
                query = @"  UPDATE Monsters
                            SET Name = @Name
                            WHERE Monsters.Id = @Id";

                //Size = @Size,
                //                Type = @Type,
                //                Subtype = @Subtype,
                //                Alignment = @Alignment,
                //                ArmorClass = @ArmorClass,
                //                HitPoints = @HitPoints,
                //                HitDice = @HitDice,
                //                Speed = @Speed,
                //                DamageVulnerabilities = @DamageVulnerabilities,
                //                DamageResistances = @DamageResistances,
                //                DamageImmunities = @DamageImmunities,
                //                ConditionImmunities = @ConditionImmunities,
                //                Senses = @Senses,
                //                Languages = @Languages,
                //                ChallengeRating = @ChallengeRating
                break;

            case InternalStates.Deleted:
                //To maybe implement in the future
                break;
        }

        List<SQLiteParameter> parameters = new List<SQLiteParameter>()
        {
            new SQLiteParameter("@Id", monster.Id ),
            new SQLiteParameter("@Name", monster.Name)
            //new SQLiteParameter("@Size", monster.Size),
            //new SQLiteParameter("@Type", monster.Type),
            //new SQLiteParameter("@Subtype", monster.Subtype),
            //new SQLiteParameter("@Alignment", monster.Alignment),
            //new SQLiteParameter("@ArmorClass", monster.ArmorClass),
            //new SQLiteParameter("@HitPoints", monster.HitPoints),
            //new SQLiteParameter("@HitDice", monster.HitDice),
            //new SQLiteParameter("@Speed", monster.Speed),
            //new SQLiteParameter("@DamageVulnerabilities", monster.DamageVulnerabilities),
            //new SQLiteParameter("@DamageResistances", monster.DamageResistances),
            //new SQLiteParameter("@DamageImmunities", monster.DamageImmunities),
            //new SQLiteParameter("@ConditionImmunities", monster.ConditionImmunities),
            //new SQLiteParameter("@Senses", monster.Senses),
            //new SQLiteParameter("@Languages", monster.Languages),
            //new SQLiteParameter("@ChallengeRating", monster.ChallengeRating)
        };

        SQLiteCommand command = new SQLiteCommand(query, sqliteConnection);
        command.Parameters.AddRange(parameters.ToArray());

        int i = command.ExecuteNonQuery();

        monster.SetInternalState(InternalStates.UnModified, true);

        sqliteConnection.Close();
    }

我已经检查过并且数据库中存在该 ID。它应该找到一个结果。如果有人知道原因并可以向我解释，那将让我开心！

更新

我仍然不知道为什么它适用于第一个示例而不适用于另一个示例，但这里有一个适合我的解决方案。

sql 参数有一个 DbType 属性，它会自动设置为适合该值，在我的例子中它被设置为 Guid。在 Sqlite 中，uniqueidentifier 类型不存在，它像字符串一样处理。所以这就是我所做的：

        ...

        List<SQLiteParameter> parameters = new List<SQLiteParameter>()
        {
            new SQLiteParameter("@Id", monster.Id ) {DbType = DbType.String},
            new SQLiteParameter("@Name", monster.Name)
            //new SQLiteParameter("@Size", monster.Size),
            //new SQLiteParameter("@Type", monster.Type),
            //new SQLiteParameter("@Subtype", monster.Subtype),
            //new SQLiteParameter("@Alignment", monster.Alignment),
            //new SQLiteParameter("@ArmorClass", monster.ArmorClass),
            //new SQLiteParameter("@HitPoints", monster.HitPoints),
            //new SQLiteParameter("@HitDice", monster.HitDice),
            //new SQLiteParameter("@Speed", monster.Speed),
            //new SQLiteParameter("@DamageVulnerabilities", monster.DamageVulnerabilities),
            //new SQLiteParameter("@DamageResistances", monster.DamageResistances),
            //new SQLiteParameter("@DamageImmunities", monster.DamageImmunities),
            //new SQLiteParameter("@ConditionImmunities", monster.ConditionImmunities),
            //new SQLiteParameter("@Senses", monster.Senses),
            //new SQLiteParameter("@Languages", monster.Languages),
            //new SQLiteParameter("@ChallengeRating", monster.ChallengeRating)
        };

        ...

Answer 1

你能试着改变一下吗：

UPDATE Monsters
SET Name = @Name
WHERE Monsters.Id = @Id

到

UPDATE Monsters SET Name = @Name
WHERE Monsters.Id like @Id

在 C# 中：

    new SQLiteParameter("@Id", "%" + monster.Id + "%");

现在，您必须在 switch/case 语句上方声明列表：

 List<SQLiteParameter> parameters = new List<SQLiteParameter>()
        {
            // remove the @id parameter here
            new SQLiteParameter("@Name", monster.Name)
            //new SQLiteParameter("@Size", monster.Size),
            //new SQLiteParameter("@Type", monster.Type),
            //new SQLiteParameter("@Subtype", monster.Subtype),
            //new SQLiteParameter("@Alignment", monster.Alignment),
            //new SQLiteParameter("@ArmorClass", monster.ArmorClass),
            //new SQLiteParameter("@HitPoints", monster.HitPoints),
            //new SQLiteParameter("@HitDice", monster.HitDice),
            //new SQLiteParameter("@Speed", monster.Speed),
            //new SQLiteParameter("@DamageVulnerabilities", monster.DamageVulnerabilities),
            //new SQLiteParameter("@DamageResistances", monster.DamageResistances),
            //new SQLiteParameter("@DamageImmunities", monster.DamageImmunities),
            //new SQLiteParameter("@ConditionImmunities", monster.ConditionImmunities),
            //new SQLiteParameter("@Senses", monster.Senses),
            //new SQLiteParameter("@Languages", monster.Languages),
            //new SQLiteParameter("@ChallengeRating", monster.ChallengeRating)
        };

对于插入的情况：

parameters.Add(new SQLiteParameter("@Id", monster.Id ));

您的更新情况：

parameters.Add(new SQLiteParameter("@Id", "%" + monster.Id + "%"));

您的最终代码：

public void SaveObject(Monster monster)
{
    SQLiteConnection sqliteConnection = new SQLiteConnection(ConnectionString.Connection);
    sqliteConnection.Open();

    String query = String.Empty;
    List<SQLiteParameter> parameters = new List<SQLiteParameter>()
    {
        new SQLiteParameter("@Name", monster.Name)
        //new SQLiteParameter("@Size", monster.Size),
        //new SQLiteParameter("@Type", monster.Type),
        //new SQLiteParameter("@Subtype", monster.Subtype),
        //new SQLiteParameter("@Alignment", monster.Alignment),
        //new SQLiteParameter("@ArmorClass", monster.ArmorClass),
        //new SQLiteParameter("@HitPoints", monster.HitPoints),
        //new SQLiteParameter("@HitDice", monster.HitDice),
        //new SQLiteParameter("@Speed", monster.Speed),
        //new SQLiteParameter("@DamageVulnerabilities", monster.DamageVulnerabilities),
        //new SQLiteParameter("@DamageResistances", monster.DamageResistances),
        //new SQLiteParameter("@DamageImmunities", monster.DamageImmunities),
        //new SQLiteParameter("@ConditionImmunities", monster.ConditionImmunities),
        //new SQLiteParameter("@Senses", monster.Senses),
        //new SQLiteParameter("@Languages", monster.Languages),
        //new SQLiteParameter("@ChallengeRating", monster.ChallengeRating)
    };

    switch (monster.InternalState)
    {
        case InternalStates.New:
            query = @"  INSERT INTO Monsters(Id,
                                            Name,
                                            Size,
                                            Type,
                                            Subtype,
                                            Alignment,
                                            ArmorClass,
                                            HitPoints,
                                            HitDice,
                                            Speed,
                                            DamageVulnerabilities,
                                            DamageResistances,
                                            DamageImmunities,
                                            ConditionImmunities,
                                            Senses,
                                            Languages,
                                            ChallengeRating) 
                        VALUES (@Id,
                                @Name,
                                @Size,
                                @Type,
                                @Subtype,
                                @Alignment,       
                                @ArmorClass,
                                @HitPoints,
                                @HitDice,
                                @Speed,
                                @DamageVulnerabilities,
                                @DamageResistances,
                                @DamageImmunities,
                                @ConditionImmunities,
                                @Senses,
                                @Languages,
                                @ChallengeRating)";
                parameters.Add(new SQLiteParameter("@Id", monster.Id ));
            break;

        case InternalStates.Modified:
            query = @"  UPDATE Monsters
                        SET Name = @Name
                        WHERE Monsters.Id like @Id";

            //Size = @Size,
            //                Type = @Type,
            //                Subtype = @Subtype,
            //                Alignment = @Alignment,
            //                ArmorClass = @ArmorClass,
            //                HitPoints = @HitPoints,
            //                HitDice = @HitDice,
            //                Speed = @Speed,
            //                DamageVulnerabilities = @DamageVulnerabilities,
            //                DamageResistances = @DamageResistances,
            //                DamageImmunities = @DamageImmunities,
            //                ConditionImmunities = @ConditionImmunities,
            //                Senses = @Senses,
            //                Languages = @Languages,
            //                ChallengeRating = @ChallengeRating
            parameters.Add(new SQLiteParameter("@Id", "%" + monster.Id + "%"));
            break;

        case InternalStates.Deleted:
            //To maybe implement in the future
            break;
    }

    SQLiteCommand command = new SQLiteCommand(query, sqliteConnection);
    command.Parameters.AddRange(parameters.ToArray());

    int i = command.ExecuteNonQuery();

    monster.SetInternalState(InternalStates.UnModified, true);

    sqliteConnection.Close();
}

更新：

sqllite 不支持 GUId。将 Guid 转换为字符串或将 id 的 changind 数据类型转换为字符串可能对您有所帮助。

看这里：

SQLite Parameter Issue with Guids

C# Sqlite 参数 Working/Not 在不同页面工作

C# Sqlite Parameter Working/Not working in different pages

c#

sqlite

sqlite-net