因爲SQL字符串而複製值？

Question

我做了我自己的使用INNER JOINS的SQL字符串。這裏是我的功能：

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 }); 
} 

現在的問題是，當我點擊stocksList ListView的recipeList ListView一個項目將有多個值。像5行左右的相同值。

Answer 1

缺少與stocksdb的連接。類似這樣的：

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