CONCAT()函數用於將多個字符串連接成一個字符串,是最重要的mysql函數之一。
SELECT concat('2019-12-1',' ',date_format(transaction_time, '%H:%i:%S'))
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{"type":"doc","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"typ
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