How Can I Pass Column Names as Input Parameters in SQL Stored Procedures?

Passing column names as input parameters in SQL stored procedures

When creating stored procedures, you may encounter situations where you need to pass column names as input parameters to enhance flexibility and dynamic data processing capabilities. However, this can be a tricky task.

Consider the following code snippet:

<code class="language-sql">create procedure sp_First
@columnname varchar
AS
begin
select @columnname from Table_1
end 
exec sp_First 'sname'</code>

Unfortunately, executing this code will result in an error because SQL Server does not allow direct substitution of column names with input parameters.

To overcome this limitation, there are several approaches you can take:

Dynamic SQL:

This involves dynamically building a SQL query using input column name parameters.

<code class="language-sql">SET @sql = 'SELECT ' + @columnName + ' FROM yourTable'
sp_executesql @sql</code>

However, be sure to sanitize input to prevent potential security vulnerabilities.

CASE statement:

Alternatively, you can use the CASE statement to conditionally select column data based on input column name parameters.

<code class="language-sql">SELECT
  CASE @columnName
    WHEN 'Col1' THEN Col1
    WHEN 'Col2' THEN Col2
                ELSE NULL
  END as selectedColumn
FROM
  yourTable</code>

This method is more verbose, but is inherently safe and requires no string manipulation.

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