只要是在預設的結構描述中存取及變更資料表,就可以省略結構描述名稱。 因為ProductDescription資料行可以接受 Null 值及無值,所以在陳述式中便可以完全省略ProductDescription資料行名稱和值。 SQL -- Dropping the optional dbo and dropping the ProductDescription columnINSERTProducts (ProductID, ProductName, Price)VA...
-- Dropping the optional dbo and dropping the ProductDescription columnINSERTProducts (ProductID, ProductName, Price)VALUES(3000,'3 mm Bracket',0.52)GO 更新products 表 键入并执行以下UPDATE语句,将第二种产品的ProductName从Screwdriver更改为Flat Head Screwdriver。
It's important to remember that the columns you choose as primary keys will end up being used in other tables to refer back to the original table. It is a best practice to use the same name for the column in both tables, if at all possible. Also, you can make it easier for people...
Thus, the task of finding the primary key is easier to achieve in a separate user-defined function because we can encapsulate this work into a single function call. Let's walk through this function and see what's really going on: Copy CREATE FUNCTION dbo.fnIsColumnPrimaryKey (@sTableName...
FeatureROWGUIDCOLThe option ROWGUIDCOL is not supported for columns of memory-optimized tables. Remove theROWGUIDCOLkeyword from the column definition. FeatureFOREIGN KEYApplies to:Azure SQL Database and SQL Server starting SQL Server 2016 (13.x) ...
Reduces the number of rows to be moved for the table on the right side of the join in order to make two distribution incompatible tables compatible. The REDUCE hint is also called a semi-join hint. REPLICATE Causes the values in the joining column from the table on the right side of the...
up as a Primary Key constraint, marked in red below. You can also see SQL Server has generated the constraint_name as pk_tablename_somerandomstring to keep it unique. By default, Database Engine creates a unique clustered index on the primary key column, if no particular index is ...
spatial_column_name 指定索引所基于的空间列。 在一个空间索引定义中只能指定一个空间列;但是可以针对 geometry 或geography 列创建多个空间索引。USING 指示空间索引的分割方案。 此参数会使用下表所示的类型特定的值:展开表 列的数据类型分割方案 geometry GEOMETRY_GRID geometry GEOMETRY_AUTO_GRID 地理 ...
T-SQL 还支持“ASCII”函数,可以转换单个字符为 ASCII 码整数。本例中利用 “ASCII”函数转换“MakeFlag”值为整数。因为该列的值为“1”,所有转换后的值就是 “49”。 本例中还使用了“UNICODE”函数,该函数用来把一个字符转换为 Unicode 整数。该 函数只有一个参数:Unicode 字符表达式。在上面的例子中,“St...
ThisCREATE TABLEstatement did not totally define myCustomertable as it is represented in my relational database model above. I still need to create a primary key constraint on the columnCustomerID.This primary key constraint will ensure that no two records in this table have the sameCustomerIDva...