MariaDBで省略記号を使用してテキストを切り捨てる方法

データベース列に返されるテキストの量が長すぎる場合があります。そのテキストの短いスニペットに続けて省略記号または3つのドットを返したい場合があります。

幸い、これはMariaDBで比較的簡単に実行できます。

3つの期間

列の文字数が特定の長さを超えるたびに、（省略記号の代わりに）3つのピリオドを列に追加する例を次に示します。

SELECT 
    IF(CHAR_LENGTH(ProductDescription) > 32, 
        CONCAT(LEFT(ProductDescription, 32),"..."), 
        ProductDescription) AS "Short Desc",
    ProductDescription AS "Full Desc"
FROM Products;

結果：

+-------------------------------------+-----------------------------------------+
| Short Desc                          | Full Desc                               |
+-------------------------------------+-----------------------------------------+
| Purple. Includes left handed car... | Purple. Includes left handed carry box. |
| Blue. Includes right handed carr... | Blue. Includes right handed carry box.  |
| Approximate 45 minute waiting pe... | Approximate 45 minute waiting period.   |
| Approximate 30 minute waiting pe... | Approximate 30 minute waiting period.   |
| Wooden handle. Free wine glasses... | Wooden handle. Free wine glasses.       |
| Orange. Includes spare fingers.     | Orange. Includes spare fingers.         |
| Tied with vines. Very chewable.     | Tied with vines. Very chewable.         |
| Brown ceramic with solid handle.    | Brown ceramic with solid handle.        |
+-------------------------------------+-----------------------------------------+

この場合、CHAR_LENGTH()を使用します IF()内の関数文字列が短縮を保証するのに十分な長さであるかどうかを判断する関数。次に、LEFT()を使用します CONCAT()内の関数簡単な説明にいくつかのドットを追加する関数。

実際の省略記号の使用

ここでも、3つのドットではなく、実際の省略記号が使用されています。

SELECT 
    IF(CHAR_LENGTH(ProductDescription) > 32, 
        CONCAT(LEFT(ProductDescription, 32),"…"), 
        ProductDescription) AS "Short Desc",
    ProductDescription AS "Full Desc"
FROM Products;

結果：

+-------------------------------------+-----------------------------------------+
| Short Desc                          | Full Desc                               |
+-------------------------------------+-----------------------------------------+
| Purple. Includes left handed car…   | Purple. Includes left handed carry box. |
| Blue. Includes right handed carr…   | Blue. Includes right handed carry box.  |
| Approximate 45 minute waiting pe…   | Approximate 45 minute waiting period.   |
| Approximate 30 minute waiting pe…   | Approximate 30 minute waiting period.   |
| Wooden handle. Free wine glasses…   | Wooden handle. Free wine glasses.       |
| Orange. Includes spare fingers.     | Orange. Includes spare fingers.         |
| Tied with vines. Very chewable.     | Tied with vines. Very chewable.         |
| Brown ceramic with solid handle.    | Brown ceramic with solid handle.        |
+-------------------------------------+-----------------------------------------+

省略記号はより少ないスペースを使用します。これは、3つのドット（3つの別々の文字）ではなく、1つの文字であるためです。

長さに関係なく、すべての行を切り捨てます

長さに関係なく、すべての行を切り捨てる必要がある場合は、IF()を含める必要はありません。機能。

この場合、コードは次のように短縮できます。

SELECT 
    CONCAT(LEFT(ProductDescription, 15), '...') AS "Short Desc",
    ProductDescription AS "Full Desc"
FROM Products;

結果：

+--------------------+-----------------------------------------+
| Short Desc         | Full Desc                               |
+--------------------+-----------------------------------------+
| Purple. Include... | Purple. Includes left handed carry box. |
| Blue. Includes ... | Blue. Includes right handed carry box.  |
| Approximate 45 ... | Approximate 45 minute waiting period.   |
| Approximate 30 ... | Approximate 30 minute waiting period.   |
| Wooden handle. ... | Wooden handle. Free wine glasses.       |
| Orange. Include... | Orange. Includes spare fingers.         |
| Tied with vines... | Tied with vines. Very chewable.         |
| Brown ceramic w... | Brown ceramic with solid handle.        |
+--------------------+-----------------------------------------+

省略記号を省略

また、省略記号/ 3つのピリオドさえ必要ない場合は、さらに短くして、次のようにすることもできます。

SELECT 
    LEFT(ProductDescription, 15) AS "Short Desc",
    ProductDescription AS "Full Desc"
FROM Products;

結果：

+-----------------+-----------------------------------------+
| Short Desc      | Full Desc                               |
+-----------------+-----------------------------------------+
| Purple. Include | Purple. Includes left handed carry box. |
| Blue. Includes  | Blue. Includes right handed carry box.  |
| Approximate 45  | Approximate 45 minute waiting period.   |
| Approximate 30  | Approximate 30 minute waiting period.   |
| Wooden handle.  | Wooden handle. Free wine glasses.       |
| Orange. Include | Orange. Includes spare fingers.         |
| Tied with vines | Tied with vines. Very chewable.         |
| Brown ceramic w | Brown ceramic with solid handle.        |
+-----------------+-----------------------------------------+