也就是说我们当判断某个值为NULL会做什么,不为NULL再做什么,这时用查询语言SQL描述如下: IF ISNULL(something) -- do something 1. 2. 我们用自然语言角度来看,翻译为如果something为NULL我们做什么,这个时候是不一致的。因为在SQL Server中没有布尔值类型,上述我们只能进行如下转换 IF something IS NULL -- d...
Applies to:SQL ServerAzure SQL DatabaseAzure SQL Managed InstanceAzure Synapse AnalyticsAnalytics Platform System (PDW)SQL analytics endpoint in Microsoft FabricWarehouse in Microsoft FabricSQL database in Microsoft Fabric Evaluates the arguments in order and returns the current value of the first express...
在SQL中常见的运算符有算术运算符(+,-),逻辑运算符(in,not in),比较运算符(>,<)等等。但是,如果参与运算的数据中存在null值,这个时候我们就要小心了,因为对于null值参与的运算可能会返回null值。 情况1:与null值列相加 比如有如下表: 当我们对每行的列字段相加时,会出现null值 SELECT Jan + Feb + Mar ...
Applies to:SQL ServerAzure SQL DatabaseAzure SQL Managed InstanceAzure Synapse AnalyticsAnalytics Platform System (PDW)SQL analytics endpoint in Microsoft FabricWarehouse in Microsoft FabricSQL database in Microsoft Fabric Evaluates the arguments in order and returns the current value of the first express...
The following example uses COALESCE to compare the values in three columns and return only the non-null value found in the columns.SQL Kopiëren CREATE TABLE dbo.wages ( emp_id TINYINT NULL, hourly_wage DECIMAL NULL, salary DECIMAL NULL, commission DECIMAL NULL, num_sales TINYINT NULL )...
SQL Server Compact Technical Reference SQL Reference (SQL Server Compact) Save Add to Collections Add to Plan Share via Facebookx.comLinkedInEmail Print Article 09/28/2009 In this article Syntax Arguments Return Value Example Returns the first nonnull expression among its arguments. ...
Si applica a: SQL Server database SQL di Azure Istanza gestita di SQL di Azure endpoint di analisi SQL di Azure Synapse Analytics Platform System (PDW) in Microsoft Fabric Warehouse nel database SQL di Microsoft Fabric in Microsoft FabricValuta...
considered to be NOT NULL, while expressions involving COALESCE with non-null parameters is considered to be NULL. In SQL Server, to index expressions involving COALESCE with non-null parameters, the computed column can be persisted using the PERSISTED column attribute as in the following statement...
IDENTITY Property (SQL Server Compact) IN (SQL Server Compact) Information Schema (SQL Server Compact) INSERT (SQL Server Compact) IS [NOT] NULL (SQL Server Compact) LEN (SQL Server Compact) LIKE (SQL Server Compact) LOG (SQL Server Compact) LOG10 (SQL Server Compact) LOWER (SQL Server ...
SQL Server / MS Access SELECT ProductName,UnitPrice*(UnitsInStock+ISNULL(UnitsOnOrder,0)) FROM Products Oracle Oracle 没有 ISNULL() 函数。不过,我们可以使用 NVL() 函数达到相同的结果: SELECT ProductName,UnitPrice*(UnitsInStock+NVL(UnitsOnOrder,0)) ...