Microsoft Access doesn't directly support CASE statements like some other database systems. Attempts to use them will result in errors. However, you can achieve the same results using the built-in IIF()
and Switch()
functions.
The IIF()
function provides conditional logic. Its structure is:
<code class="language-sql">IIF(condition, true_result, false_result)</code>
For example, to find the maximum date between two fields (LASTSERVICEDATE
and [Last CP12 Date]
), you would use:
<code class="language-sql">IIF(dbo_tbl_property.LASTSERVICEDATE > Contour_dates.[Last CP12 Date], dbo_tbl_property.LASTSERVICEDATE, Contour_dates.[Last CP12 Date])</code>
This returns LASTSERVICEDATE
if it's greater; otherwise, it returns [Last CP12 Date]
.
For more complex scenarios, the Switch()
function offers a multi-conditional approach:
<code class="language-sql">Switch( expr1, value1, expr2, value2, ..., exprN, valueN )</code>
Each expr
is evaluated sequentially. If an expr
is true, its corresponding value
is returned. Importantly, Access evaluates all expressions, even after a match is found. Be mindful of potential errors or unexpected behavior due to this characteristic.
Remember to adapt these examples to your specific field and table names. For finding the maximum date across multiple columns or rows, more advanced SQL techniques like MAX()
within subqueries or aggregate functions might be necessary.
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