我有一个用于降价格式的博客帖子正文的MySQL字段。由于我使用的API，我只能发送3000个字符块，但是我的一些帖子大到4500个字符，并且有超过2000个字符，所以我不想手动拆分它们。
我正在尝试找出一个函数来检查列中每个字段的char_length，如果它超过3000个字符，该函数会将超过3000个字符（四舍五入到最近的单词）的任何内容拆分成第二列有。它超出了我之前处理的功能范围，所以我希望能够朝着正确的方向发展。这是我到目前为止的基础：
SELECT `Body` from `blogposts`
WHERE char_length(Body) > 3000
SET
Body2 = SUBSTRING(`Body`, 3001, char_length(Body))
Body = SUBSTRING(`Body`, 1, 3000)
由于尚未完成，我还没有测试过。我不相信它会接近我想做的事情，但我在测试之前仍然试图解决的另外两个问题是：
1）如何将它移到最近一个单词的末尾（向下舍入到3000个字符以下），而不是精确地分成第3000个字符。
2）如果尝试处理单词，它会在文本中的markdown / html上中断，例如将<div>拆分为<div" ">，如果这是第3000个字符。
对于背景，我已经阅读了以下内容：
Split string into table in groups of 26 characters or less, rounded to the nearest word
响应似乎已经提出了自定义函数来根据设定的长度拆分字符串，虽然函数没有得到很好的解释/评论，所以我有点迷失。
如果在MySQL中做起来不容易，我愿意在PHP中将其拉出来并在那里操纵数据。
任何见解都将不胜感激！
答案 0 :(得分：2)
update `blogposts`
set `Body2` = substring(`Body`,3000-instr(reverse(left(`Body`,3000)),' ')+1)
,`Body` = left(`Body`,3000-instr(reverse(left(`Body`,3000)),' '))
where char_length(Body) > 3000
;
演示30个字符
set @Body = 'My name is Inigo Montoya! You''ve killed my father, prepare to die!';
select left(@Body,30-instr(reverse(left(@Body,30)),' ')) as field_1
,substring(@Body,30-instr(reverse(left(@Body,30)),' ')+1) as field_2
;
+---------------------------+------------------------------------------+
| field_1 | field_2 |
+---------------------------+------------------------------------------+
| My name is Inigo Montoya! | You've killed my father, prepare to die! |
+---------------------------+------------------------------------------+
create table `blogposts` (`Body` varchar(3000),`Body2` varchar(3000));
insert into blogposts (`Body`) values
('Hello darkness, my old friend' )
,('I''ve come to talk with you again' )
,('Because a vision softly creeping' )
,('Left its seeds while I was sleeping' )
,('And the vision that was planted in my brain' )
,('Still remains' )
,('Within the sound of silence' )
,('In restless dreams I walked alone' )
,('Narrow streets of cobblestone' )
,('''Neath the halo of a street lamp' )
,('I turned my collar to the cold and damp' )
,('When my eyes were stabbed by the flash of a neon light' )
,('That split the night' )
,('And touched the sound of silence' )
,('And in the naked light I saw' )
,('Ten thousand people, maybe more' )
,('People talking without speaking' )
,('People hearing without listening' )
,('People writing songs that voices never share' )
,('And no one dared' )
,('Disturb the sound of silence' )
;
select left(`Body`,30-instr(reverse(left(`Body`,30)),' ')) as Body
,substring(`Body`,30-instr(reverse(left(`Body`,30)),' ')+1) as Body2
from `blogposts`
where char_length(Body) > 30
;
+------------------------------+---------------------------+
| Body | Body2 |
+------------------------------+---------------------------+
| I've come to talk with you | again |
+------------------------------+---------------------------+
| Because a vision softly | creeping |
+------------------------------+---------------------------+
| Left its seeds while I was | sleeping |
+------------------------------+---------------------------+
| And the vision that was | planted in my brain |
+------------------------------+---------------------------+
| In restless dreams I walked | alone |
+------------------------------+---------------------------+
| 'Neath the halo of a street | lamp |
+------------------------------+---------------------------+
| I turned my collar to the | cold and damp |
+------------------------------+---------------------------+
| When my eyes were stabbed by | the flash of a neon light |
+------------------------------+---------------------------+
| And touched the sound of | silence |
+------------------------------+---------------------------+
| Ten thousand people, maybe | more |
+------------------------------+---------------------------+
| People talking without | speaking |
+------------------------------+---------------------------+
| People hearing without | listening |
+------------------------------+---------------------------+
| People writing songs that | voices never share |
+------------------------------+---------------------------+
update `blogposts`
set `Body2` = substring(`Body`,30-instr(reverse(left(`Body`,30)),' ')+1)
,`Body` = left(`Body`,30-instr(reverse(left(`Body`,30)),' '))
where char_length(`Body`) > 30
;
select `Body`
,`Body2`
from `blogposts`
where `Body2` is not null
;
+------------------------------+---------------------------+
| Body | Body2 |
+------------------------------+---------------------------+
| I've come to talk with you | again |
+------------------------------+---------------------------+
| Because a vision softly | creeping |
+------------------------------+---------------------------+
| Left its seeds while I was | sleeping |
+------------------------------+---------------------------+
| And the vision that was | planted in my brain |
+------------------------------+---------------------------+
| In restless dreams I walked | alone |
+------------------------------+---------------------------+
| 'Neath the halo of a street | lamp |
+------------------------------+---------------------------+
| I turned my collar to the | cold and damp |
+------------------------------+---------------------------+
| When my eyes were stabbed by | the flash of a neon light |
+------------------------------+---------------------------+
| And touched the sound of | silence |
+------------------------------+---------------------------+
| Ten thousand people, maybe | more |
+------------------------------+---------------------------+
| People talking without | speaking |
+------------------------------+---------------------------+
| People hearing without | listening |
+------------------------------+---------------------------+
| People writing songs that | voices never share |
+------------------------------+---------------------------+
答案 1 :(得分：1)
该代码将始终将字符串除以3000个字符并将其推送到数组。无论字符长度是多少，您都可以使用此代码块。不要忘记，如果你的文字的字符低于3000，那么$ bodyParts变量中只有1个元素。
$bodyText; // That came from SQL Ex Query : SELECT body FROM blogposts
$bodyParts = [];
$lengthOfBody = strlen($bodyText);
if($lengthOfBody > 3000){
$forLoopInt = ceil($lengthOfBody / 3000); // For example if your body text have 3500 characters it will be 2
echo $forLoopInt;
for($i = 0; $i<= $forLoopInt - 2; $i++){
$bodyParts[] = substr($bodyText, ($i) * 3000 , 3000);
}
// lets fetch the last part
$bodyParts[] = substr( $bodyText,($forLoopInt - 1) * 3000);
}else{
$bodyParts[] = $bodyText;
}
/* anyway if your body text have characters lower than 3000 , bodyParts array will contain just 1 element, if not it will have Ceil(Length of body / 3000) elements in it. */
var_dump($bodyParts);