從字符串到Blob

Question

我想在group_concat命令中使用concat_ws。隨着查詢，其中簡化看起來像：

SELECT item.title, GROUP_CONCAT(CONCAT_WS( ',', attachments.id, attachments.type,  attachments.name)) as attachments 
FROM story AS item 
LEFT OUTER JOIN story_attachment AS attachments ON item.id = attachments.item_id 
GROUP BY item.id 

我得到附件列作爲Blob類型。是否有可能把它作爲一個字符串而不是Blob？

Answer 1

你需要轉換爲一個char ..

SELECT item.title, GROUP_CONCAT(CAST(CONCAT_WS(',', attachments.id, 
attachments.type, attachments.name) as CHAR)) as attachments 
FROM story AS item 
LEFT OUTER JOIN story_attachment AS attachments 
ON item.id = attachments.item_id GROUP BY item.id 

Answer 2

雖然我懷疑CAST是合適的答案，這是值得一提的是我遇到了在過去類似的事情，這竟然是下降到一個奇怪/衝突的排序類型和字符集。