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...
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...
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...
CASE expression syntax is similar to an IF-THEN-ELSE statement. Oracle checks each condition starting from the first condition (left to right). When a particular condition is satisfied (WHEN part) the expression returns the tagged value (THEN part). If none of the conditions are matched, the...
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 ...
That’s a query that’s both ugly and useless; just an extreme example of using CASE expressions all over the place. Considerations for Nesting CASE expressions can be nested: DECLARE @tier int = 2; SELECT CASE WHEN @tier > 1 THEN ...
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 ...
possible. Aggregate expressions that appear in WHEN arguments to aCASEexpression are evaluated first, then provided to theCASEexpression. For example, the following query produces a divide by zero error when producing the value of the MAX aggregate. This occurs prior to evaluating theCASEexpression....
In this example, cte_expression_1 references the cte_expression_2. When the CTE is defined, we can use it in the subsequent expressions. The most common use case for nested CTEs is applying aggregate functions inside one another, such as when we need to find the average minimum or maximum...
Table functions are functions that can produce a set of rows as output. In other words, table functions return a collection type instance (nested table and VARRAY datatypes). You can use a table function in place of a regular table in the FROM clause of a SQL statement....