C# 中的 SQL Server 更新语句

Question

I have table SelectedType with columns type_1 ... type_2_3 of datatype bit :

P_ID   type_1 type_1_1 type_1_2 type_1_3 type_2 type_2_1 type_2_2 type_2_3

 1        0      1         1       0       0       1        0        1       
 2        1      0         1       0       0       1        0        0
 3        1      0         1       0       0       1        0        0
 4        0      0         0       1       1       1        1        1
...and so on 

And JSON Array

[
  {"value": "type_1_1"}, {"value": "type_2_1"}, {"value": "type_2_3"}
]

How can I update the SQL Server table using for loop and if {"value": "type_1_1"} equals to table Column name type_1_1 then set value to 1 or if value is 1 then set to 0?

Here is what I'm trying so far:

public bool UpdatePredictSubGoalType(int id, string _selectedTypes)
{
        string a = "[]";
        string item = _selectedTypes;

        if (!item.Contains('[') && !item.Contains(']'))
        {
            string c = a.Insert(1, _selectedTypes);
            item = c;
        }

        bool res = false;

        JArray Ja = JArray.Parse(item);
        string sqlstr = "";

        try
        {
            using (conn = new SqlConnection(CommonDA.GetConnectionString()))
            {
                conn.Open();
                trans = conn.BeginTransaction();

                try
                {
                    for (int i = 0; i <= Ja.Count - 1; i++)
                    {
                        string x = Ja[i]["value"].ToString();

                        SqlCommand cmd = conn.CreateCommand();
                        sqlstr = @"Update SelectedType set "+ x +" = (0 or 1, i don't know how to do) where id = @id AND " + x + " = @" + x;
                        cmd.CommandText = sqlstr;
                        cmd.Transaction = trans;
                        cmd.Parameters.AddWithValue("@id", id);                            

                        cmd.ExecuteNonQuery();

                        trans.Commit();
                        conn.Close();

                        res = true;
                    }
                }
                catch (Exception Err)
                {
                    trans.Rollback();
                    CommonLB.SystemError(Err.Message);
                    CommonLB.SystemError("Data", "SQL:" + sqlstr);
                }
            }
        }
        catch (Exception Err)
        {
            throw new ApplicationException(Err.Message, Err);
        }

        return res;
    }

Answer 1

Assuming what I mentioned in the comments is correct (that presence of a value defines 1, absence defines 0) I think, before you set your 1s you'll need to set everything to 0, or get into having a collection of all your columns so C# can work out what should be 0..

Something like this (install Dapper to make ExecuteAsync on a connection "a thing", or expand it to "the long way"):

    using var conn = new SqlConnection(CommonDA.GetConnectionString()));

    var sql = "UPDATE t SET type_1=0, type_1_1=0, type_1_2=0, type_1_3=0, type_2=0, type_2_1=0, type_2_2=0, type_2_3=0 WHERE ID = @id";

    for (int i = 0; i <= Ja.Count - 1; i++){
      var c = Ja[i]["value"].ToString();

      if(!Regex.IsMatch(c, @"^type_\d(_\d)?$")
        continue;
      sql = sql.Replace($"{c}=0", $"{c}=1");
    }

    await conn.ExecuteAsync(sql, new { id });

We start off by naming very column in the table, and setting it type_x_y=0 . Then for every column name present in the json, we change that part of the SQL to type_x_y=1 with a bit of string replacement

The Regex is in there to guard against SQL injection attacking by the json supplier

Answer 2

You can just pass the whole JSON array into SQL, and have SQL Server break it down.

• Use OPENJSON to bring out separate rows
• Pivot it back into a single row, each column having a 1 or 0
• Use a combination of ISNULL and NULLIF to keep the same value
  • If you want to overwrite all columns then you can simply do type_1 = j.type_1

UPDATE st
SET
  type_1   = IIF(j.type_1   = 1, 1, st.type_1  ),
  type_1_1 = IIF(j.type_1_1 = 1, 1, st.type_1_1),
  type_1_2 = IIF(j.type_1_2 = 1, 1, st.type_1_2),
  type_1_3 = IIF(j.type_1_3 = 1, 1, st.type_1_3),
  type_2   = IIF(j.type_2   = 1, 1, st.type_2  ),
  type_2_1 = IIF(j.type_2_1 = 1, 1, st.type_2_1),
  type_2_2 = IIF(j.type_2_2 = 1, 1, st.type_2_2),
  type_2_3 = IIF(j.type_2_3 = 1, 1, st.type_2_3)
FROM SelectedType st
CROSS APPLY (
    SELECT *
    FROM OPENJSON(@json)
      WITH (value sysname) j
    PIVOT (COUNT(value) FOR value IN
        (type_1, type_1_1, type_1_2, type_1_3, type_2, type_2_1, type_2_2, type_2_3)
    ) pvt
) j
WHERE st.P_ID = @id;

Then your application code becomes very simple

public bool UpdatePredictSubGoalType(int id, string _selectedTypes)
{
    if (!item.StartsWith('['))
        _selectedTypes = '[' + _selectedTypes;
    if (!item.EndsWith(']'))
        _selectedTypes = _selectedTypes + ']';

    try
    {
        const string query = @"
THE ABOVE QUERY
";
        using (var conn = new SqlConnection(CommonDA.GetConnectionString()))
        using (var cmd = new SqlCommand(query, conn))
        {
            cmd.Parameters.Add("@id", SqlDbType.Int).Value = id;                            
            cmd.Parameters.Add("@json", SqlDbType.NVarChar, -1).Value = _selectedTypes;
            conn.Open();
            cmd.ExecuteNonQuery();
        }
    }
    catch (Exception Err)
    {
        throw new ApplicationException(Err.Message, Err);
    }

    return true;
}

Answer 3

更改您的 sql 字符串：

str = $"Update SelectedType set [{x}] = CASE WHEN [{x}] = 0 then 1 else 0 end where id = {@id}";