Question

我试图主要从一个表中查询数据，但我还需要来自同一数据库中另一个表的两列。我的查询的一部分看起来像这样：

SELECT
      'Contact 1' AS "Phone 2 - Type",
      Emerg_Phone_1 AS "Phone 2 - Value",
      'Contact 2' AS "Phone 3 - Type",
      Emerg_Phone_2 AS "Phone 3 - Value",
      'Student Cell' AS "Phone 4 - Type",
      STUDENTCELL AS "Phone 4 - Value",
FROM STUDENTS JOIN STUDENTS2

所以基本上，除了STUDENTCELL以外，所有五个选择都来自STUDENTS表，但我在同一个查询中需要STUDENTS2表中的一列STUDENTCELL。感谢您提供任何帮助和建议，我对mySQL和oracle都很陌生。

Answer 1

你几乎得到了解决方案。除了join子句之外。您需要使用common列连接两个表。因此，您可以使用ON Clause或Using clause。 b / w的基本差异是

USING子句

如果多个列共享相同的名称但您不想使用所有这些公共列进行连接，则使用USING子句。 USING子句中列出的列在语句中不能包含任何限定符，包括WHERE子句：

ON条款

ON子句用于连接两个表中列名不匹配的表。连接条件将从WHERE子句中的过滤条件中删除：

我将Common列视为ID。如果两个表都有不同的列名，请使用on

SELECT
      'Contact 1' AS "Phone 2 - Type",
      Emerg_Phone_1 AS "Phone 2 - Value",
      'Contact 2' AS "Phone 3 - Type",
      Emerg_Phone_2 AS "Phone 3 - Value",
      'Student Cell' AS "Phone 4 - Type",
      STUDENTCELL AS "Phone 4 - Value",
FROM STUDENTS JOIN STUDENTS2 ON (STUDENTS.Stud_ID=STUDENTS2.Stud2_ID)

如果两个表具有相同的列名，则使用using

SELECT
      'Contact 1' AS "Phone 2 - Type",
      Emerg_Phone_1 AS "Phone 2 - Value",
      'Contact 2' AS "Phone 3 - Type",
      Emerg_Phone_2 AS "Phone 3 - Value",
      'Student Cell' AS "Phone 4 - Type",
      STUDENTCELL AS "Phone 4 - Value",
FROM STUDENTS JOIN STUDENTS2 using (id);

您可能需要浏览Oracle JOINS和SQL JOINS

Answer 2

假设var bx1 = $(".bx1"); var bx2 = $(document.querySelectorAll(".bx2"));是两个表中的公共字段，以下查询应该执行作业

student_id

Oracle - 尝试从同一查询中的两个表中查询数据

2 个答案: