How to Simulate LastIndexOf Functionality in SQL Server?

Mock LastIndexOf function in SQL Server

SQL Server itself does not directly provide an equivalent to the LastIndexOf function commonly used in programming languages. However, there are other ways we can find the last occurrence of a substring in a string.

Use CHARINDEX and REVERSE functions

One way is to use the CHARINDEX and REVERSE functions together. This approach can be lengthy and cumbersome, as shown in the code provided in the question:

SELECT REVERSE(SUBSTRING(REVERSE(DB_NAME()), 1,
    CHARINDEX('_', REVERSE(DB_NAME()), 1) - 1))

Use RIGHT and REVERSE functions

For a more efficient and readable solution, you can combine the RIGHT and REVERSE functions. This method allows you to retrieve the substring following the last occurrence of a specified character, like this:

select right(db_name(), charindex('_', reverse(db_name()) + '_') - 1)

Use the LEFT and REVERSE functions

Similarly, to retrieve the substring before the last occurrence, you can use the LEFT function:

select left(db_name(), len(db_name()) - charindex('_', reverse(db_name()) + '_'))

By using these techniques, you can efficiently perform last index operations in SQL Server, providing a more intuitive and efficient alternative to the original approach.

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