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I have a problem whilst trying to display MySQL data in a table format. Basically, I have a table which stores payments with the fields amount, item, currency and location. I want to display these in a table that shows the locations across the top, the currencies on the second row, the items in the first columns row and then the sum of the payments within the rest of the table corresponding to the location/currency. Here is an example of my MySQL table data:

item        | amount | currency | location
----------------------------------------------
Item 1      | 250    | USD      | UK    
Item 2      | 450    | GBP      | UK
Item 3      | 780    | EUR      | Germany   
Item 2      | 50     | GBP      | Spain
Item 2      | 150    | GBP      | Spain
Item 4      | 375    | USD      | UK
Item 4      | 650    | GBP      | Germany
Item 1      | 350    | USD      | UK

The end result I'm looking to achieve would be something like:

        |  Germany  | Spain |     UK    |
        | EUR | GBP |  GBP  | GBP | USD |
        ---------------------------------
Item 1  |     |     |       |     | 600 |
Item 2  |     |     |  200  | 450 |     |
Item 3  | 780 |     |       |     |     |
Item 4  |     | 650 |       |     | 375 |

At the moment, I am achieving the result using multiple queries which uses lots of nested queries for each of the items as follows:

<table width="1046" border="0">
  <tr>
    <td></td>
    <td colspan="2">Germany</td>
    <td>Spain</td>
    <td colspan="2">UK</td>
  </tr>
  <tr>
    <td></td>
    <td>EUR</td>
    <td>GBP</td>
    <td>GBP</td>
    <td>GBP</td>
    <td>USD</td>
  </tr>
  <? $q1 = mysqli_query("SELECT item FROM table1 group by item order by item asc");
  while($row1 = mysqli_fetch_assoc($q1)){
    $item = $row1['item']; ?>
    <tr>
      <td><? echo $item; ?></td>

      <? $q2 = mysqli_query("SELECT sum(amount) as amt from table1 WHERE currency='EUR' and item='$item' and location='Germany'");
      while($row2 = mysqli_fetch_assoc($q2)){ ?>
        <td><? echo number_format($row2['amt'],0); ?></td>
      <? } ?>

      <? $q3 = mysqli_query("SELECT sum(amount) as amt from table1 WHERE currency='GBP' and item='$item' and location='Germany'");
      while($row3 = mysqli_fetch_assoc($q3)){ ?>
        <td><? echo number_format($row3['amt'],0); ?></td>
      <? } ?>

      <? $q4 = mysqli_query("SELECT sum(amount) as amt from table1 WHERE currency='GBP' and item='$item' and location='Spain'");
      while($row4 = mysqli_fetch_assoc($q4)){ ?>
        <td><? echo number_format($row4['amt'],0); ?></td>
      <? } ?>

      <? $q5 = mysqli_query("SELECT sum(amount) as amt from table1 WHERE currency='GBP' and item='$item' and location='UK'");
      while($row5 = mysqli_fetch_assoc($q5)){ ?>
        <td><? echo number_format($row5['amt'],0); ?></td>
      <? } ?>

      <? $q6 = mysqli_query("SELECT sum(amount) as amt from table1 WHERE currency='USD' and item='$item' and location='UK'");
      while($row6 = mysqli_fetch_assoc($q6)){ ?>
        <td><? echo number_format($row6['amt'],0); ?></td>
      <? } ?>
    </tr>
    <? } ?>
</table>

I am wondering if there is a better way of achieving the same result?

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2 回答 2

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MySQL 没有 PIVOT 函数，但如果您想在一个查询中检索此数据，则可以使用带有CASE表达式的聚合函数将数据从行获取到列中：

select item,
  sum(case when location = 'Germany' and currency = 'EUR' then amount else 0 end) Ger_EUR,
  sum(case when location = 'Germany' and currency = 'GBP' then amount else 0 end) Ger_GBP,
  sum(case when location = 'Spain' and currency = 'GBP' then amount else 0 end) Spa_GBP,
  sum(case when location = 'UK' and currency = 'GBP' then amount else 0 end) UK_GBP,
  sum(case when location = 'UK' and currency = 'USD' then amount else 0 end) UK_USD
from table1
group by item;

请参阅SQL Fiddle with Demo。这给出了结果：

|   ITEM | GER_EUR | GER_GBP | SPA_GBP | UK_GBP | UK_USD |
----------------------------------------------------------
| Item 1 |       0 |       0 |       0 |      0 |    600 |
| Item 2 |       0 |       0 |     200 |    450 |      0 |
| Item 3 |     780 |       0 |       0 |      0 |      0 |
| Item 4 |       0 |     650 |       0 |      0 |    375 |
于 2013-04-14T10:55:39.693 回答
1

如果位置和货币是固定列表，那么您可以使用以下查询

SELECT item,
       SUM(CASE WHEN location = 'Germany' AND currency = 'EUR' THEN amount ELSE NULL END) Germany_EUR,
       SUM(CASE WHEN location = 'Germany' AND currency = 'GBP' THEN amount ELSE NULL END) Germany_GBP,
       SUM(CASE WHEN location = 'Spain' AND currency = 'GBP' THEN amount ELSE NULL END) Spain_GBP,
       SUM(CASE WHEN location = 'UK' AND currency = 'GBP' THEN amount ELSE NULL END) UK_GBP,
       SUM(CASE WHEN location = 'UK' AND currency = 'USD' THEN amount ELSE NULL END) UK_USD
  FROM yourtable
 GROUP BY item

这是SQLFiddle

于 2013-04-14T10:56:29.167 回答