SQL 中自然连接和内部连接的区别
先决条件–连接(内部、左侧、右侧和完全连接) 1。自然连接: 自然连接基于相同的属性名和数据类型连接两个表。生成的表将包含两个表的所有属性，但只保留每个公共列的一个副本。
示例: 考虑下面给出的两个表格:
学生表
标记表
考虑给定的查询
SELECT *
FROM Student NATURAL JOIN Marks;
输出:
2。内部连接: 内部连接基于 on 子句中明确指定的列连接两个表。结果表将包含两个表的所有属性，包括公共列。
示例: 考虑以上两个表，查询如下:
SELECT *
FROM student S INNER JOIN Marks M ON S.Roll_No = M.Roll_No;
输出:
SQL 中 Natural JOIN 和 INNER JOIN 的区别:
| SR number | Natural JOIN | 内部连接 | | --- | --- | --- | | 1。 | Natural join connects two tables based on the same attribute name and data type. | Inner join joins two tables according to the columns explicitly specified in the on clause. | | 2。 | In a natural join, the result table will contain all the attributes of the two tables, but only one copy will be kept for each common column. | In the inner join, the result table will contain all the attributes of the two tables, including duplicate columns. | | 3。 | In a natural join, if no condition is specified, rows based on common columns are returned. | In an inner join, only exists in two tables. | | 4 will be returned. | Syntax: Select * from Table 1 Natural Connection Table 2; | Syntax: Select * Table 2 internal connection in Table 1\. Column name = Table 2\. Column name; |SQL Server 管理工作室不支持自然连接，也称为微软 SQL Server。
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