How Can I Implement Conditional Logic in Microsoft Access Without a CASE Statement?

Implement conditional expressions in Access

Access is a well-known database management system that lacks the typical CASE expression syntax. However, it provides alternative ways to handle conditional evaluation.

Use the IIF() function

As an alternative to CASE, Access provides the IIF() function. It follows a simple syntax:

<code>IIF(condition, valueiftrue, valueiffalse)</code>

• condition determines whether to return valueiftrue or valueiffalse.
• valueiftrue and valueiffalse represent condition-based results.

This code demonstrates how to use IIF() to compare two dates:

<code>IIF(dbo_tbl_property.LASTSERVICEDATE > Contour_dates.[Last CP12 Date], dbo_tbl_property.LASTSERVICEDATE, Contour_dates.[Last CP12 Date])</code>

Use Switch function

Alternatively, Access provides the Switch function:

<code>Switch(expr-1, value-1 [, expr-2, value-2 ] … [, expr-n, value-n ] )</code>

For each expr, if true, return the corresponding value. Otherwise, the next expr is evaluated until the True condition is met.

Note that the Switch function evaluates expressions slightly differently than IIF().

Example

To illustrate, here's how to use the Switch function to evaluate multiple conditions:

<code>Switch(
    dbo_tbl_property.LASTSERVICEDATE <p>这些函数为在 Access 数据库中实现条件逻辑提供了多功能选项，以满足特定的评估要求。</p></code>

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