下拉选项查询sql返回重复

Question

如何停止查询我的下拉列表重复，如下图所示？

请选择CD价格：

<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

您可以使用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 2

从数据库中选择DISTINCT值（唯一值）

double double_values[18];
for(int i = 0; i < 18; i++) {
    //Your code here
}  

Answer 3

这应该这样做：

SELECT DISTINCT nmc_cd.CDPrice FROM nmc_cd

祝你好运!!

Answer 4

在table中，column可能包含许多duplicate values;有时您只想列出different (distinct) values。

DISTINCT 关键字可用于仅返回不同（不同）的值。

语法：

 SELECT DISTINCT column_name,column_name
    FROM table_name;

Answer 5

尝试执行以下代码。 请选择CD价格：

<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>