包含用于替换返回OSI模型表示层应用层会话层传输层网络层数据链路层SQL ServerISNULL 函数NULL 值其它指定值 从上图可以看出,ISNULL函数在 SQL Server 中位于应用层,直接影响数据的处理方式。 抓包方法 为了更好地理解ISNULL函数的使用,可以通过抓包来实际分析 SQL 语句的执行情况。 思维导图展示了抓包的流程: 抓包...
ExampleGet your own SQL Server Return the specified value IF the expression is NULL, otherwise return the expression: SELECTISNULL(NULL,'W3Schools.com'); Try it Yourself » Definition and Usage The ISNULL() function returns a specified value if the expression is NULL. ...
The SQL Server ISNULL function returns the replacement value if the first parameterexpressionevaluates to NULL. SQL Server converts the data type of replacement to data type of expression. Let’s explore SQL ISNULL with examples. 如果第一个参数表达式的计算结果为NULL,则SQL Server ISNULL函数将返回...
The code samples in this article use theAdventureWorks2022orAdventureWorksDW2022sample database, which you can download from theMicrosoft SQL Server Samples and Community Projectshome page. A. Use ISNULL with AVG The following example finds the average of the weight of all products. It substitutes...
expression:任何有效的SQServer表达式。 AS:用于分隔两个参数,在AS之前的是要处理的数据,在AS之后是要转换的数据类型。 data_type:目标系统所提供的数据类型,包括bigint和sql_variant,不能使用用户定义的数据类型。 使用CAST函数进行数据类型转换时,在下列情况下能够被接受: ...
sql server 的 isnull 函数 selectISNULL(NULL,0) --是NULL的时候 置0selectISNULL(null,0) --null的时候 置0selectISNULL('123',0) --'123'的时候 置123
SQL Server The SQL ServerISNULL()function lets you return an alternative value when an expression is NULL: SELECTProductName, UnitPrice * (UnitsInStock + ISNULL(UnitsOnOrder,0)) FROMProducts; or we can use theCOALESCE()function, like this: ...
Applies to:SQL ServerAzure SQL DatabaseAzure SQL Managed Instance Creates a user-defined function (UDF), which is a Transact-SQL or common language runtime (CLR) routine. A user-defined function accepts parameters, performs an action such as a complex calculation, and returns the result of ...
Applies to:SQL ServerAzure SQL DatabaseAzure SQL Managed Instance Creates a user-defined function (UDF), which is a Transact-SQL or common language runtime (CLR) routine. A user-defined function accepts parameters, performs an action such as a complex calculation, and returns the result of ...
ISNULL() (SQL Server / MS Access) NVL() (Oracle) IFNULL() (MySQL) COALESCE() (MySQL) (22)通用数据类型 4、SQL函数 (1)SQL 聚合函数 SQL Aggregate 函数计算从列中取得的值,返回一个单一的值。 AVG() - 返回平均值 COUNT() - 返回行数 ...