How Can I Work Around CASE WHEN Limitations in MS Access Queries via ODBC?

Using the CASE WHEN Clause with MS Access through ODBC

When connecting to Microsoft Access databases using ODBC, it is essential to understand the limitations of the CASE WHEN clause.

While the CASE WHEN clause is commonly used in other databases to conditionally compute new columns, MS Access does not fully support it. This can lead to exceptions if an ODBC connection is used with a query containing the CASE WHEN clause.

For MS Access, a workaround is to use the switch() function instead. This function allows for the selection between multiple return values based on specified conditions. To use the switch() function, enclose each condition in parentheses followed by the desired return value, separated by commas. The final parameter should be the default return value.

Here's an example:

SELECT switch(
  age > 40, 4,
  age > 25, 3,
  age > 20, 2,
  age > 10, 1,
  true, 0
) FROM demo

In this example, the switch() function evaluates the age column and returns the corresponding value based on the conditions. The default value (0) is returned if none of the conditions are met.

Remember, the default return value is necessary to prevent null values if none of the conditions match.

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