查找mysql中两列共有的值

Question

+ table one  +
+----------------------+
|column A | Column B|
|   2     |    4    | 
|   3     |    5    |
|   6     |    1    |
|   1     |    2    |
|   8     |    7    |
+----------------------+

Output
+-------+
|   1   |
|   2   |
+-------+

我想在输出中输入1和2，因为1 and 2 are present in column A as well as column B。

Answer 1

<script src="https://rawgit.com/darkskyapp/skycons/master/skycons.js"></script>
<div class="fe_forecast">
    <div class="fe_currently">
        <canvas id="fe_current_icon" data-icon="cloudy" width="160" height="160" style="width:120px; height:120px"></canvas>
    </div>
</div>

以下是 DEMO http://sqlfiddle.com/#!9/72e9a/1

希望这有帮助

Answer 2

您可以使用：

SELECT sub1.col
FROM (SELECT DISTINCT `column A` AS col
      FROM table_one) sub1
JOIN (SELECT DISTINCT `column B` AS col
      FROM table_one) sub2
ON sub1.col = sub2.col;

或相关子查询：

SELECT `column A` 
FROM table_one t1
WHERE EXISTS (SELECT 1
              FROM table_one t2
              WHERE t2.`column B` = t1.`column A`

Answer 3

您可以使用此代码块解决您的问题：

position: relative

去：SQL Fiddle