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sqlserver中的case函数在oracle中有没有对应的函数？
先给出decode说明，再给出example
Decoded Expression
A decoded expression uses the special DECODE syntax:
To evaluate this expression, Oracle compares expr to each search value one by one. If expr is equal to a search, Oracle returns the corresponding result. If no match is found, Oracle returns default, or, if default is omitted, returns null. If expr and search contain character data, Oracle compares them using nonpadded comparison semantics. For information on these semantics, see the section "Datatype Comparison Rules".
The search, result, and default values can be derived from expressions. Oracle evaluates each search value only before comparing it to expr, rather than evaluating all search values before comparing any of them with expr. Consequently, Oracle never evaluates a search if a previous search is equal to expr.
Oracle automatically converts expr and each search value to the datatype of the first search value before comparing. Oracle automatically converts the return value to the same datatype as the first result. If the first result has the datatype CHAR or if the first result is null, then Oracle converts the return value to the datatype VARCHAR2. For information on datatype conversion, see "Data Conversion".
In a DECODE expression, Oracle considers two nulls to be equivalent. If expr is null, Oracle returns the result of the first search that is also null.
The maximum number of components in the DECODE expression, including expr, searches, results, and default is 255.
oracle 和 sqlserver 中的函数区别：
DECODE
CASE WHEN if 条件
Then value1
Else
value2
End
case就是decode撒
