Скачать или смотреть Correcting Your CASE Statement in PLSQL: A Guide to Avoiding ORA-00936 Errors

Learn how to fix your PLSQL `CASE` statement and avoid the ORA-00936 missing expression error with this detailed guide.
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This video is based on the question https://stackoverflow.com/q/70882791/ asked by the user 'LH44' ( https://stackoverflow.com/u/16314019/ ) and on the answer https://stackoverflow.com/a/70883101/ provided by the user 'Marmite Bomber' ( https://stackoverflow.com/u/4808122/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding the ORA-00936 Error in PLSQL

When working with PLSQL, developers sometimes encounter errors that can be frustrating. One such error is ORA-00936 missing expression, which typically indicates a problem with the query syntax. This error can halt your progress, especially when dealing with complex SELECT statements. Today, we will discuss a specific case related to this error and how to resolve it.

The Problem: Syntax Error in Your CASE Statement

You have the following SELECT statement that is producing the ORA-00936 error:

[[See Video to Reveal this Text or Code Snippet]]

The issue seems to stem from how the CASE statement is being used in the WHERE clause. Let's dive into how to fix this.

Solution: Reformulating the CASE Statement

To resolve the ORA-00936 error, it's important to adhere to structured logic in your CASE statement. Here’s a way to look at it, organized into clear parts.

Step 1: Simplifying the Logic

Understanding Conditions

You always want end_date to be greater than your greatest expression in certain cases.

When the condition for l_neg_esn_allowed indicates that it's not restricted (i.e., != 'N'), end_date can be equal to the result of the comparison.

Step 2: Using a Proper Predicate

By restructuring the conditions, you can formulate the WHERE clause using logical operators:

[[See Video to Reveal this Text or Code Snippet]]

This predicate structure checks both scenarios based on the NVL(l_neg_esn_allowed,'N') condition.

Step 3: Alternative Predicate

An alternative way that resembles your initial intention could be:

[[See Video to Reveal this Text or Code Snippet]]

This format ensures clarity and helps the SQL engine properly interpret the conditions without causing any syntax issues.

Conclusion

By restructuring the CASE statement in your PLSQL query using these guidelines, you can effectively avoid the ORA-00936 missing expression error. Remember to always break down complex statements into manageable parts, ensuring that each logical condition is clear and correctly formulated. Happy coding!