因为SQL语句导致数值重复？

Question

我编写了一个使用INNER JOIN的自定义SQL字符串。以下是我的函数:

string cmdstr = @"SELECT s.*, mdb.menu_name
                  FROM stocksdb s, recipelist rl
                  INNER JOIN menudb mdb  ON rl.menu_ID = mdb.menu_ID
                  WHERE rl.stock_ID = '" + stockID + "'";

var cmd = new MySqlCommand(cmdstr, db.mycon);
var dr = cmd.ExecuteReader();
while (dr.Read())
{
    var menuname = dr["menu_name"].ToString();

    stockIDTxtbox.Text = stockID;
    nameTxtBox.Text = dr["stock_name"].ToString();
    availableTxtbox.Text = dr["stock_quantity"].ToString();
    pricePerPieceTxtbox.Text = dr["stock_pricePerPiece"].ToString();
    limitTxtBox.Text = dr["stock_limit"].ToString());

    recipeList.Items.Add(new ListViewItem(new[] { menuname });
}

现在的问题是，当我在“stocksList ListView”上点击一个项目时，“recipeList ListView”会有多个值。例如，相同值的5行或更多行。

- John Ernest Guadalupe

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请纠正我 SQL 语法方面的问题。 - John Ernest Guadalupe

你能提供一些样本数据吗？ - Trisped

Answer 1

缺少与stocksdb的连接。类似这样的代码:

   SELECT s.*, mdb.menu_name 
   FROM stocksdb s

   INNRER JOIN recipelist rl 
   ON s.stock_ID= r1.stock_ID   <== this join was missing

   INNER JOIN menudb mdb 
   ON rl.menu_ID = mdb.menu_ID 
   WHERE rl.stock_ID = '" + stockID 

- alexm