JOIN 表2 ON 关联条件 SQL JOIN的类型 SQL 支持不同类型的 JOIN 操作,包括: INNER JOIN(内连接):返回两个表中满足 JOIN 条件的匹配行。 LEFT JOIN(左连接):返回左表中的所有行,以及右表中满足 JOIN 条件的匹配行。如果右表中没有匹配的行,则返回 NULL 值。 RIGHT JOIN(右连接):返回右表中的所有行,以...
Example-- join the Customers and Orders tables -- based on the common values of their customer_id columns SELECT Customers.customer_id, Customers.first_name, Orders.item FROM Customers JOIN Orders ON Customers.customer_id = Orders.customer_id; Run Code Here, the SQL command joins the Customers...
Example 2 – SQL Join on Multiple Columns This example SQL statement shows a multi-column join including 3 tables. The Product table is included in the SELECT clause to show the product Name. The table ProductCostHistory and ProductPriceHistory are used to show the difference between the produc...
6、left semi join 中最后 select 的结果只许出现左表,因为右表只有 join key 参与关联计算了,而 join on 默认是整个关系模型都参与计算了 7、对待右表中重复key的处理方式差异:因为 left semi join 是 in(keySet) 的关系,遇到右表重复记录,左表会跳过,而 join on 则会一直遍历做 key 内 cross join REF:...
SQL JOINThe JOIN keyword is used in an SQL statement to query data from two or more tables, based on a relationship between certain columns in these tables. Tables in a database are often related to each other with keys.SYNTAX :
Here, the SQL command performs an inner join on theCategoriesandProductstables while assigning the aliasesCandPto them, respectively. SQL INNER JOIN With Three Tables We can also join more than two tables usingINNER JOIN. For example,
INNER JOIN 是一种 SQL 操作,它通过共享相同值的列将两个或多个表连接在一起。INNER JOIN 会返回满足连接条件的行,即只返回两个表中列值相等的行。 INNER JOIN 的结果是一个新的表,其中包含了所有满足连接条件的行。通过 INNER JOIN,我们可以从多个表中获取相关的数据,以便进行更复杂的查询和分析。 INNER JO...
RIGHT OUTER JOIN [Purchasing].[Vendor] as v ON po.VendorID = v.BusinessEntityID ORDER BY po.OrderDate, v.BusinessEntityID; GO Example 1 Results A partial result set is shown below. We see in the results that there are Vendors who do not have Purchase Orders thus their PurchaseOrderHear...
The INNER JOIN command returns rows that have matching values in both tables.The following SQL selects all orders with customer information:ExampleGet your own SQL Server SELECT Orders.OrderID, Customers.CustomerNameFROM OrdersINNER JOIN Customers ON Orders.CustomerID = Customers.CustomerID; Try ...
Example Let's look at an example that shows how to use the FULL OUTER JOIN in a SELECT statement. Using the samecustomerstable as the previous example: customer_idlast_namefirst_namefavorite_website 4000JacksonJoetechonthenet.com 5000SmithJanedigminecraft.com ...