为什么我得到，“；找不到表0”；

在程序启动时，如果SQL Server CE表不存在，我将创建一个表，并向其中添加一条记录：

if (dbconn.isValidTable("hhs_settings") == -1) // <-- (IOW, it's *not* a valid table)
{
    DBUtils.CreateSettingsTable();
    AppSettings.WriteSettingsVal("beltprinter", "None");
}
public static void CreateSettingsTable()
{
    try
    {
        string sqlddl =
            "create table hhs_settings (setting_id int identity (1,1) Primary key,  setting_name varchar(40) not null, setting_value(63) varchar not null)";
        dbconn.DBCommand(sqlddl, false);        
    }
    catch (SqlCeException sqlcex)
    {
        MessageBox.Show("sqlcex - CreateSettingsTable " + sqlcex.Message);
    }
    catch (Exception ex)
    {
        MessageBox.Show("CreateSettingsTable " + ex.Message);
    }
}

但当我打开一个从表中读取的表格时：

lblSelectedPrinter.Text = AppSettings.ReadSettingsVal("beltprinter");

它以"找不到表0"失败

public static string ReadSettingsVal(string settingName)
{
    string retVal = string.Empty;
    string sqldml = string.Format("select setting_value from hhs_settings where setting_name = {0}", " + settingName + ");
    // There should only be one value returned, but using the existing getDataSet() method for now...
    DataSet dsSettingVal = frmCentral.dbconn.getDataSet(sqldml);
    foreach (DataRow row in dsSettingVal.Tables[0].Rows)
    {
        if (retVal == string.Empty)
        {
            retVal = row["setting_value"].ToString();
        }
    }
    return retVal;
}

我是不是错过了一个步骤，所以没有创建表（hhs_settings）？或

更新

即使在更改了所有格式愚蠢的字符串后，我仍然会收到相同的错误消息：

string sqldml = string.Format("insert into hhs_settings (setting_name, setting_value) values('{0}', '{1}')", settingName, settingVal);
string sqlqry = string.Format("select setting_value from hhs_settings where setting_name = '{0}'", settingName);

而且，我仍然看到消息"即将创建hhs_settings"，尽管据推测，createtable sql已经很好了：

string sqlddl =
    "create table hhs_settings (setting_id int identity (1,1) Primary key,  setting_name varchar(40) not null, setting_value(63) varchar not null)";

因此，应该已经创建了表（这应该使isValidTable（）方法返回除-1之外的值（当找不到表时返回的值）。

更新2

当我把ddl改为：时，它起了作用（现在有效）

字符串sqlddl="创建表hhs_settings（setting_id int identity（1,1）主键，setting_name nvarchar（40）不为null，setting_value nvarchal（63）不为null）"；

string.Format("select setting_value from hhs_settings where setting_name = {0}", " + settingName + ");

select setting_value from hhs_settings where setting_name =  + settingName + 

string.Format("select setting_value from hhs_settings where setting_name = '{0}'", settingName);