Question

我正在尝试从动态生成的textbox gridview数据库中插入数据。但是，我得到的例外CommandText属性尚未初始化cmd.executeNonQuery();

private void InsertRecords(StringCollection sc)
{
    StringBuilder sb = new StringBuilder(string.Empty);
    string[] splitItems = null;
    const string sqlStatement = "INSERT INTO Ingredients_List (Ingredients1) VALUES";
    foreach (string item in sc)
    {
        if (item.Contains(","))
        {
            splitItems = item.Split(",".ToCharArray());
            sb.AppendFormat("{0}('{1}'); ", sqlStatement, splitItems[0]);
        }

    }
    //  conn.Open();
    using (SqlConnection connn = new SqlConnection(GetConnectionString()))

    {
        using (SqlCommand cmd = new SqlCommand(sb.ToString(), connn))
        {
            connn.Open();
            //      cmd.CommandType = CommandType.Text;
            cmd.ExecuteNonQuery();
            connn.Close();
        }
        // Page.ClientScript.RegisterClientScriptBlock(typeof(Page), "Script", "alert('Records Successfuly Saved!');", true);
    }
}

Answer 1

您的问题是由于您在循环之后没有检查是否在StringBuilder中插入了任何内容。如果没有带逗号的字符串，那么，foreach语句中的内部条件会使stringbuilder保持为空，命令将永远不会有正确的命令文本。

解决方法应该很简单，比如添加测试以查看StringBuilder中是否有一些文本，但我更倾向于使用List<SqlParameter>

建议您采用不同的方法

StringBuilder sb = new StringBuilder(string.Empty);
List<SqlParameter> prms = new List<SqlParameter>();
string[] splitItems = null;

// Base string for creating parameter placeholders dynamically
string sqlStatement = "INSERT INTO Ingredients_List (Ingredients1) VALUES (@p{0});";

int count = 1;
foreach (string item in sc)
{
    if (item.Contains(","))
    {
        splitItems = item.Split(',');

        // Parameter name created dynamically
        prms.Add(new SqlParameter($"@p{count}", SqlDbType.NVarChar) {Value=splitItems[0]});

        // Create the placeholder for the nth parameter
        sb.AppendFormat(sqlStatement, count);
    }
}

// Don't execute anything if there are no parameters (or stringbuilder empty)
if(prms.Count > 0)
{
    using (SqlConnection connn = new SqlConnection(GetConnectionString()))
    using (SqlCommand cmd = new SqlCommand(sb.ToString(), connn))
    {
        connn.Open();

        // Add all parameters together
        cmd.Parameters.AddRange(prms);
        cmd.ExecuteNonQuery();
    }
}

Answer 2

您没有将查询的第一部分加载到StringBuilder。试试这个：

private void InsertRecords(StringCollection sc)
{
    const string sqlStatement = "INSERT INTO Ingredients_List (Ingredients1) VALUES";
    StringBuilder sb = new StringBuilder(sqlStatement);
    string[] splitItems = null;
    foreach (string item in sc)
    {
        if (item.Contains(","))
        {
            splitItems = item.Split(",".ToCharArray());
           sb.AppendFormat("{0}('{1}'); ", sqlStatement, splitItems[0]);
        }
    }
    //  conn.Open();
    using (SqlConnection connn = new SqlConnection(GetConnectionString()))
    {
        using (SqlCommand cmd = new SqlCommand(sb.ToString(), connn))
        {
            connn.Open();
            //      cmd.CommandType = CommandType.Text;
            cmd.ExecuteNonQuery();
            connn.Close();
        }
        // Page.ClientScript.RegisterClientScriptBlock(typeof(Page), "Script", "alert('Records Successfuly Saved!');", true);
    }
}

编辑 - 我已经构建了一个测试数据库并调试了以下代码。它适用于我传递的测试数据。

    private void InsertRecords(StringCollection sc)
    {
        const string sqlStatement = "INSERT INTO Ingredients_List (Ingredients1) VALUES";
        StringBuilder sb = new StringBuilder();

        foreach (string item in sc)
        {
            if (item.Contains(","))
            {
                var splitItems = item.Split(",".ToCharArray());
                sb.AppendFormat("{0}('{1}'); ", sqlStatement, splitItems[0]);
            }

        }
        Console.WriteLine(sb.ToString());
        //  conn.Open();
        using (SqlConnection connn = new SqlConnection(ConfigurationManager.ConnectionStrings["whatever"].ConnectionString))

        {
            using (SqlCommand cmd = new SqlCommand(sb.ToString(), connn))
            {
                connn.Open();
                cmd.ExecuteNonQuery();
                connn.Close();
            }
            // Page.ClientScript.RegisterClientScriptBlock(typeof(Page), "Script", "alert('Records Successfuly Saved!');", true);
        }
    }

我按如下方式测试了它：

...
var collection = new StringCollection{"a,x", "b,y", "c,z"};

InsertRecords(collection);

执行数据库查询以查看数据如下：

SELECT [Ingredients1]
  FROM [Ingredients_List]

结果：

Ingredients1
------------
a
b
c

ExecuteNonQuery：CommandText属性尚未在c＃中初始化

2 个答案: