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方法一:CONCAT_WS --使用CONCAT_WS连接姓名和地址,并以逗号分隔: SELECT CONCAT_WS(', ', first_name, middle_name, last_name, address) AS full_info FROM person; 方法二:CONCAT 函数 阅读全文
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COALESCE(discount_price, price) --若有折扣价,显示折扣价; --若无折扣价,显示原价; 阅读全文
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extra1(string):{"systemtype":"ios","education":"master","marriage_status":"1","phonebrand":"iphone X"}extra2(map<string,string>) {"systemtype":"ios"," 阅读全文
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(8) SELECT (9)DISTINCT<Select_list> (1) FROM <left_table> (3) <join_type>JOIN<right_table> (2) ON<join_condition> (4) WHERE<where_condition> (5) GROUP 阅读全文