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SQL 语句 关于 INNER JOIN 使用注意
SELECT P_info.*, p_pingpa.* FROM P_info INNER JOIN p_pingpa ON P_info.p_other = p_pingpa.pi_id;
INNER JOIN 功能是：将两个相关系的表在内部结合成一查询表
SELECT P_info.*,p_pingpa.* 要查询的项
FROM P_info 来自哪个表
INNER JOIN p_pingpa 内部要加入的哪个表
ON P_info.p_other=p_pingpa.pi_id 主键和外键 给出相关联的字段
============================= 联接多表时使用
SELECT tlbOrderList.*, P_class.p_type
FROM (tlbOrderList INNER JOIN P_info ON tlbOrderList.p_id = P_info.p_id) INNER JOIN P_class ON P_info.p_class_id = P_class.p_id
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