How decode will work in SQL?
DECODE compares the expression to each search value one by one. If expression is equal to a search, then the corresponding result is returned by the Oracle Database. If a match is not found, then default is returned. If default is omitted, then Oracle returns null.
How do I decode a value in SQL query?
The basic syntax for writing DECODE function in SQL is as follows: DECODE (expression , search_1, result_1[, search_2, result_2], …,[,search_n,result_n] [, default]); The parameters used in the above mentioned syntax are: expression: expression argument is the value which is to be searched and compared with.
Which is better case or decode in Oracle?
CASE is better than DECODE because it is easier to read, and can handle more complicated logic. As far as performance goes, there is minimal difference between CASE and DECODE, so it should not be a factor in your decisions.
How do I use decode?
The DECODE function returns a value that is the same datatype as the first result in the list. If the first result is NULL, then the return value is converted to VARCHAR2. If the first result has a datatype of CHAR, then the return value is converted to VARCHAR2. If no matches are found, the default value is returned.
Can we use decode inside decode?
It is possible to use DECODE, but you’d have to use nested DECODEs and you’d end up with something that’s much harder to read, understand and therefore maintain.
What is the use of 1 1 in SQL?
The 1=1 is ignored by always all rdbms. There is no tradeoff executing a query with WHERE 1=1. Building dynamic WHERE conditions, like ORM frameworks or other do very often, it is easier to append the real where conditions because you avoid checking for prepending an AND to the current condition.
Which SQL keyword is used to retrieve a maximum value?
MAX() is the SQL keyword is used to retrieve the maximum value in the selected column.
What is Nullif SQL Server?
Description. In SQL Server (Transact-SQL), the NULLIF function compares expression1 and expression2. If expression1 and expression2 are equal, the NULLIF function returns NULL. Otherwise, it returns the first expression which is expression1.
Which is faster decode or case?
From performance perspective, In Oracle decode and CASE does not make any difference. But in Exadata , Decode is faster than CASE. The Decode operation is done at storage Server level where the data is present BUT CASE is done at DB Instance level which receives data from DB storage Level.
What is difference between NVL and NVL2?
What is the difference between nvl and nvl2? Answer: The nvl function only has two parameters while the nvl parameter has three arguments. The nvl2 like like combining an nvl with a decode because you can transform a value: NVL ( expr1 , expr2 ): If expr1 is null, then NVL returns expr2.
Can we use null in Decode Oracle?
DECODE. The DECODE function is not specifically for handling null values, but it can be used in a similar way to the NVL function, as shown by the following example.
What is difference between procedure and function?
Function is used to calculate something from a given input. Hence it got its name from Mathematics. While procedure is the set of commands, which are executed in a order.
How do I use NVL2?
NVL2 lets you determine the value returned by a query based on whether a specified expression is null or not null. If expr1 is not null, then NVL2 returns expr2 . If expr1 is null, then NVL2 returns expr3 . The argument expr1 can have any datatype.