In the previous example, we start by selecting the film titles and grouping each film by its rental rate. Finally, we use the nested CASE WHEN statements to create different groups based on the rental rate. We then check the rental durations and return the corresponding message. An example o...
In the simplest case, when a query returns one row, its form is that shown in the last example (in which EMPNO is a unique key). However, if a query can return more than one row, you must fetch the rows using a cursor or select them into a host array. If a query is written t...
It’s also possible to start an entire new CASE expression on a THEN or ELSE argument. For example, this T-SQL statement has a nested CASE expression: SELECT [BusinessEntityID],[JobTitle],[BirthDate],CASE WHEN [JobTitle]LIKE'%Marketing%'THEN CASE WHEN [BirthDate]>='1984-01-01'THEN'S...
By default, SQL Server can use an optimized Nested Loops join instead of a full scan or a Nested Loops join with an explicit Sort, when the Query Optimizer concludes that a sort is most likely not required, but still a possibility if the cardinality or cost estimates are incorrect. For ...
use of any comparison operator and checking multiple conditions, all in a SQL query itself. Moreover, using the CASE function, multiple conditions provided in separate SQL queries can be combined into one, thus avoiding multiple statements on the same table (example given below). The function is...
There are times where you need to write a single TSQL statement that is able to return different TSQL expressions based on the evaluation of another expression. When you need this kind of functionality you can use the CASE expression or IIF function to meet this requirement. In this article ...
When an alias isn't used,exposed_object_nameis the exact match of the table or view referenced in theFROMclause. For example, if the table or view is referenced using a two-part name,exposed_object_nameis the same two-par...
User-defined functions can be nested; that is, one user-defined function can call another. The nesting level is incremented when the called function starts execution, and decremented when the called function finishes execution. User-defined functions can be nested up to 32 levels. Exceeding the ...
override def batches:Seq[Batch]=Seq(Batch("Substitution",fixedPoint,// This rule optimizes `UpdateFields` expression chains so looks more like optimization rule. // However, when manipulating deeply nested schema, `UpdateFields` expression tree could be // very complex and make analysis impossible...
Prevents a spool operator from being added to query plans (except for the plans when spool is required to guarantee valid update semantics). The spool operator can reduce performance in some scenarios. For example, the spool usestempdb, andtempdbcontention can occur if there are many concurrent ...