下拉選項查詢sql返回重複

Question

我如何停止查詢我的下拉重複，如下圖所示？

請選擇CD價格：

<select name="CDPrice"> 
    <option value=""> 
     <?php 
     include 'database_conn.php'; 
     if (!(is_object($conn) && (get_class($conn) == 'mysqli'))) { 
      die("DB connection failure."); 
     } 
     $rsCDprice = mysqli_query($conn, "SELECT nmc_cd.CDPrice FROM nmc_cd"); 
     if (!$rsCDprice) { 
      die("No result from DB query."); //probably invalid SQL, table error, etc. 
     } 
     if ($rsCDprice->num_rows < 1) { 
      die("No rows returned from DB query."); //query runs OK, but nothing is found in DB to match. 
     } 
     while ($Catpriceresult = mysqli_fetch_array($rsCDprice)) { 
      echo "<option value='" . $Catpriceresult[0] . "'>" . $Catpriceresult[0] . "</option>"; 
     } 
     ?> 
</select> 

Answer 1

嘗試執行下面的代碼。 請選擇CD價格：

<select name="CDPrice"> 
    <option value=""> 
     <?php 
     include 'database_conn.php'; 
     if (!(is_object($conn) && (get_class($conn) == 'mysqli'))) { 
      die("DB connection failure."); 
     } 
     $rsCDprice = mysqli_query($conn, "SELECT DISTINCT nmc_cd.CDPrice FROM nmc_cd"); 
     if (!$rsCDprice) { 
      die("No result from DB query."); //probably invalid SQL, table error, etc. 
     } 
     if ($rsCDprice->num_rows < 1) { 
      die("No rows returned from DB query."); //query runs OK, but nothing is found in DB to match. 
     } 
     while ($Catpriceresult = mysqli_fetch_array($rsCDprice)) { 
      echo "<option value='" . $Catpriceresult[0] . "'>" . $Catpriceresult[0] . "</option>"; 
     } 
     ?> 
</select> 

Answer 2

您可以使用此DISTINCT或group by。

1. group by

   SELECT nmc_cd.CDPrice FROM nmc_cd GROUP BY nmc_cd.CDPrice

2. DISTINCT

   SELECT DISTINCT nmc_cd.CDPrice FROM nmc_cd

Answer 3

選擇從DB（唯一值）DISTINCT值

SELECT DISTINCT nmc_cd.CDPrice FROM nmc_cd 

Answer 4

這應做到：

SELECT DISTINCT nmc_cd.CDPrice FROM nmc_cd 

祝你好運！

Answer 5

在table中，column可能包含許多duplicate values;有時你只想列出different (distinct) values。

DISTINCT關鍵字可用於僅返回不同的（不同的）值。

語法：

SELECT DISTINCT column_name,column_name 
    FROM table_name;