RUNOOB sql教程
包括:截取字符串前幾位,後幾位,或者從中間開始的某幾位 MySQL 字符串函數:字符串截取
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{"type":"doc","content":[{"type":"blockquote","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null
{"type":"doc","content":[{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"text","text":"背景介紹","att