How to Split Strings in T-SQL with Missing Delimiters?

Delimiter-based string splitting in T-SQL, handling missing delimiters

In T-SQL, you may need to split a string based on a specific delimiter, even if that delimiter is not always present. This task is typically performed using the SUBSTRING function. However, the code provided in the question fails when a line is missing the expected delimiter.

To resolve this issue, consider the following modified code:

<code class="language-sql">SELECT 
    CASE 
        WHEN CHARINDEX('/', myColumn) = 0 THEN myColumn
        ELSE SUBSTRING(myColumn, 1, CHARINDEX('/', myColumn) - 1)
    END AS FirstName,
    CASE 
        WHEN CHARINDEX('/', myColumn) = 0 THEN NULL
        ELSE SUBSTRING(myColumn, CHARINDEX('/', myColumn) + 1, LEN(myColumn))
    END AS LastName
FROM MyTable;</code>

In this code, a CASE statement is used to determine where the substrings for the FirstName and LastName columns begin and end. The starting position of the FirstName column is set to the beginning of the string (if no delimiter is found) or the character before the delimiter. Similarly, the end position of the FirstName column is set to the end of the string or the character before the delimiter.

This method ensures that the code can handle lines with expected delimiters as well as lines without expected delimiters without generating errors. The resulting output will provide the required FirstName and LastName values, even for rows without delimiters, where missing values ​​will appear as NULL. This is more concise and efficient than the original code, and handles missing delimiters more clearly.

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