How Can I Efficiently Trim Leading Zeros from SQL Server Columns?

Tip to optimize the removal of leading zeros in SQL Server

To remove leading zeros from a column in SQL Server, the traditional method is to use a combination of the SUBSTRING function and the PATINDEX function. However, this approach may run into problems when dealing with columns containing only "0" characters.

To work around this limitation, a more robust solution is to add a period (.) to the end of the string being checked:

<code class="language-sql">SUBSTRING(str_col, PATINDEX('%[^0]%', str_col+'.'), LEN(str_col))</code>

This period ensures that PATINDEX will always find a non-"0" character match, even for columns with only leading zeros.

Another way is to use the TRIM and REPLACE functions:

<code class="language-sql">REPLACE(LTRIM(REPLACE(str_col, '0', ' ')), ' ', '0')</code>

However, this method requires caution when dealing with embedded spaces. To avoid converting spaces to "0", you can use a custom scalar user-defined function (UDF). Scalar UDFs can cause performance issues in SQL Server 2005, so it is recommended to consider other methods where feasible.

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