The SQL JOIN statement is used to combine rows from two tables based on a common column and selects records that have matching values in these columns. Example -- join the Customers and Orders tables -- based on the common values of their customer_id columns SELECT Customers.customer_id, ...
syntaxsql 複製 FROM { [ , ...n ] } ::= { [ database_name . [ schema_name ] . | schema_name . ] table_or_view_name [ AS ] table_or_view_alias [ <tablesample_clause> ] | derived_table [ AS ] table_alias [ ( column_alias [ , ...n ] ) ] | <joined_table> } ...
In the above query, SQL update statement is used to updates a table named "bill" and sets the value of the "room_charge" column to 600 for all records in the "bill" table that meet a certain condition. The condition is defined by a join operation between the "bill" table and the "...
2. From the previous query you can see that Lars Bender's scored a goal in game 1012. Now we want to know what teams were playing in that match. Notice in the that the column matchid in the goal table corresponds to the id column in the game table. We can look up information abou...
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...
SQL INNER JOIN The SQLINNER JOINstatement joins two tables based on a common column and selects rows that have matching values in these columns. Example -- join Customers and Orders tables with their matching fields customer_idSELECTCustomers.customer_id, Orders.itemFROMCustomersINNERJOINOrdersON...
Notice that the "CustomerID" column in the "Orders" table refers to the "CustomerID" in the "Customers" table. The relationship between the two tables above is the "CustomerID" column. Then, we can create the following SQL statement (that contains an INNER JOIN), that selects records th...
1.1.1. SQL简史 SQL最初基于关系代数(relational algebra)和元组关系演算(tuple relational calculus),由多种类型的语句(statement)组成。SQL 是计算机科学领域历史上的关键里程碑,是计算历史上最成功的想法之一。 追溯到 1970 年代初,SQL 发展简史如下。
SQL IN Code The IN statement can be used to find rows in a query where one column can be matched to a value in a list of values. The list of values can be hard coded as a comma-separated list or can come from a subquery as it does in this example. ...
derived _table 可以使用 Transact-SQL 表值构造函数功能来指定多个行。 例如,SELECT * FROM (VALUES (1, 2), (3, 4), (5, 6), (7, 8), (9, 10) ) AS MyTable(a, b);。 有关详细信息,请参阅表值构造函数 (Transact-SQL)。 column_alias ...