SQL子查询和 LEFT JOIN 关键字

SQL子查询 语法： sno in (SELECT sno FROM p_test WHERE category =“800米” ) WHERE category=“立定跳远” and sno in (SELECT sno FROM p_test WHERE category =“800米” ) 上述语句的意思就是2个条件，类型是立定跳远，学号是类型为800米的所有学号 SQL LEFT JOIN

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