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Question

我有一个SELECT语句，可以在下表中成功填充我需要的数据。但是我想用if语句过滤掉结果。基本上我想把它放在哪里：

如果Timestamp和/或msg有值，则获得结果，否则留空。

<?php foreach ( $result as $query ){ ?>
    <tr>
        <td><?php echo $query->text1; ?></td>
        <td><?php echo $query->text2; ?></td>
        <td><?php echo $query->text3; ?></td>
        <td><?php if($query->Timestamp!=""){echo date('m/d/y', strtotime($query->Timestamp)); }?></td>
        <td><?php echo $query->msg; ?></td>
    </tr>
<?php }?>

如何将此if语句写入此代码，以便仅显示生成date或msg或两者的行？

根据要求，我已经添加了初始查询，虽然有点复杂，因此我希望避免进一步搞乱它。

$result = $wpdb->get_results(
    "SELECT DISTINCT text3,
        CASE WHEN text3 LIKE '%S' THEN S_Msg
             WHEN text3 LIKE '%N' THEN N_Msg
             ELSE E_Msg
             END AS msg,
        CASE WHEN text3 LIKE '%S' THEN S_Time
             WHEN text3 LIKE '%N' THEN N_time
             WHEN text3 LIKE '%E' THEN E_time
             END AS Timestamp,
        value1
        FROM table_1 AS a
        INNER JOIN table_2 AS b
            ON a.Value2 = b.Value3
        WHERE value1='$value1'");

我愿意接受有效解决方案的建议：）

更新

我尝试过使用M Khalid Junaid提出的建议

 having (msg is not null and msg <> '')
 or (Timestamp is not null and Timestamp <> '')

但是这会导致其他查询不再加载的问题，因为我没有使用组，而是在页面上有多个不同的查询，这只是一组更大的查询中的一个。

我担心这个是我的头脑。要在sqlfiddle上复制这个，我需要设置3个数据库表，所以需要一天准备，除非有人有另一个解决方案。我仍然对if语句中的警察持开放态度lol

Answer 1

要获得满足任何条件的结果，您可以使用以下

select  distinct text3,
        case when text3 like '%S' then S_Msg when text3 like '%N' then N_Msg else E_Msg end as msg,
        case when text3 like '%S' then S_Time when text3 like '%N' then N_time when text3 like '%E' then E_time end as Timestamp,
        value1 
from table_1 as a 
inner join table_2 as b on a.Value2 = b.Value3 
where value1='$value1'
having (msg is not null and msg <> '')
or (Timestamp is not null and Timestamp <> '')

不确定您的数据如何在NULL中保存在数据库中，或者为空，因此我添加了两个过滤器。使用having子句的目的是对自定义别名应用过滤器

Answer 2

您可以在检查时间戳或N_msg为空的末尾添加AND语句

$result = $wpdb->get_results(
"SELECT DISTINCT text3,
    CASE WHEN text3 like '%S' THEN S_Msg
         WHEN text3 like '%N' THEN N_Msg
         ELSE E_Msg
         END AS msg,
    CASE WHEN text3 LIKE '%S' THEN S_Time
         WHEN text3 LIKE '%N' THEN N_time
         WHEN text3 LIKE '%E' THEN E_time
         END AS Timestamp,
    value1
    FROM table_1 AS a
    INNER JOIN table_2 AS b
        ON a.Value2 = b.Value3
    WHERE value1='$value1'
    AND N_msg != '' OR S_time != '' OR N_time != '' OR E_time != ''");

Answer 3

您可以这样做 - 使用having子句中的别名

select distinct 
    text3, 
    case 
        when text3 like '%S' then S_Msg 
        when text3 like '%N' then N_Msg 
        else E_Msg 
    end as msg,
    case 
        when text3 like '%S' then S_Time 
        when text3 like '%N' then N_time 
        when text3 like '%E' then E_time 
    end as Timestamp, 
    value1 
    from table_1 as a 
    inner join table_2 as b on a.Value2 = b.Value3 
    having value1='$value1' and msg is not null and timestamp is not null

如何添加if语句以排除特定的空行

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3 个答案: