TSQL是一种用于管理和操作关系型数据库的编程语言,它支持使用CASE语句来更新多个列,但更新操作的结果取决于特定的值。 CASE语句是一种条件表达式,它允许根据不同的条件执行不同的操作。在TSQL...
实验: CASE 语句实验 --例1:根据员工数据表中每个员工所在不同部门,显示不同的信息 Use sample Go Select -- Case when ’ when ’ when ’ when ’ End From Order by 2-2-4 waitfor语句 WAITFOR 语句用于暂时停止执行 SQL 语句、语句块或者存储过程等,直到所设定的时间已过或者...
else_result_expression是任意有效的SQL Server 表达式。else_result_expression和所有result_expression的数据类型必须相同,或者必须是隐性转换。 WHEN Boolean_expression:使用CASE搜索格式时所计算的布尔表达式。Boolean_expression是任意有效的布尔表达式。 下面介绍简单CASE函数和CASE搜索函数两种格式的执行顺序。 简单CASE函数...
可以使用ALTER DATABASE语句修改数据库的默认文件组设置,但每个数据库同时最多只能有一个默认文件组。当数据库没有指定默认文件组时,主文件组将被作为默认文件 组使用。 由于默认文件组的特殊作用,所以在创建数据库对象时,即使不指定用户文件组,SQL Server也能照常执行。 1.使用Transact-SQL语句建立数据库 CREATE DA...
ORDER BY TOP/OFFSET FETCH OFFSET FETCH可以看作是ORDER BY子句的一部分 SQL基于集合理论,查询结果集(表结果)是无顺寻的(虽然看起来结果集像按照某种顺序排列),除非显式的使用ORDER BY子句指定顺寻,但使用ORDER BY字句后结果集将被作为游标对待,而非表结果。
CASE— Run a set of commands based on a predicate (not to be confused with CASE expressions). IF… ELSE— Perform conditional flow control. ITERATE— Restart a LOOP or WHILE statement. LEAVE— Exit a server code module such as stored procedure, function, ...
Can I sort row without order by clause Can I UPDATE, then INSERT if no record updated? Can I use a COLLATE clause in a temp table definition? Can I use aggregate function within CASE? Can I use if statement in a table valued function? Can I use LEN or DATALENGTH in a WHERE clause...
TOP (n) WITH TIES is used to allow overriding the n maximal number (or percentage) of rows specified in case there are additional rows with the same ordering values as the last row. Note If TOP (n) is used without WITH TIES and there are additional rows ...
Every SQL statement used in a stored procedure can get it’s own execution plan, depending on whether or not it was parameterized. Parameterized queries that are identically written (including case, spaces, and line breaks), can reuse an execution plan. Those that are not, will receive their...
The reason is that PIVOT makes an implicit GROUP BY operation behind the scenes on all columns that are not explicitly referenced by the operator. In this case, you need the salesperson ID, the order year, and the order value: Copy USE AdventureWorks SELECT SOH.SalesPersonID, YEAR(SOH....