比如以下字段内容，我要截取以::::::为分割的部分内容
"banner_2 (1).png::::::/gcjx/e/extend/uploadImg/upload/upload_files/2020-07-02/9d2cba0773d47bad2cc8f8f36ee0a344.png::::::35231 banner_2.png::::::/gcjx/e/extend/uploadImg/upload/upload_files/2020-07-02/912db94a2d747ff28ac7623b4955a28d.png::::::35232 "写法 substring_index(substring_index(uploadimg, “::::::”, 2), “::::::”, -1) as logoimg
取得的值为
/gcjx/e/extend/uploadImg/upload/upload_files/2020-07-02/9d2cba0773d47bad2cc8f8f36ee0a344.png
写法 substring_index(substring_index(uploadimg, “::::::”, 1), “::::::”, -1) as logoimg
取得的值为
banner_2 (1).png
规则如下，懂了吧
substring_index(str,delim,count)
str:要处理的字符串 delim:分隔符 count:计数