# Why SELECT INTO Fails Silently Inside MySQL IF Blocks During PL/SQL Logic Migration

**URL:** <https://forums.percona.com/t/why-select-into-fails-silently-inside-mysql-if-blocks-during-pl-sql-logic-migration/38623>\
**Category:** Other MySQL® Questions\
**Created:** [July 10, 2025, 9:18am UTC](https://forums.percona.com/t/why-select-into-fails-silently-inside-mysql-if-blocks-during-pl-sql-logic-migration/38623 "2025-07-10T09:18:48Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![benof](https://avatars.discourse-cdn.com/v4/letter/b/bcef8e/32.png) [@benof](https://forums.percona.com/u/benof)\
**Post date:** [July 10, 2025, 9:18am UTC](https://forums.percona.com/t/why-select-into-fails-silently-inside-mysql-if-blocks-during-pl-sql-logic-migration/38623/1 "2025-07-10T09:18:48Z")

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Hello

I am facing an issue in MySQL where a stored procedure using `SELECT INTO` inside an `IF` block sometimes fails to populate the variable; even though the query returns a row when executed independently. 🙃

The problem occurs intermittently & the procedure runs without error but the output variables remain NULL. 😇 I suspect it’s either due to how MySQL handles variable scope within conditional logic / because of overlapping column names across joins. 🤔

This is part of a migration from an older Oracle system where we used PL/SQL to conditionally assign variables inside blocks and the logic translated cleanly. But MySQL seems more sensitive to SELECT INTO behavior inside nested logic. 🤔

Are there hidden caveats when using `SELECT INTO` with IF/ELSE blocks in stored procedures? 🙃Does the query optimizer treat those differently compared to standalone SELECTs? I have checked [https://dev.mysql.com/doc/refman/8.4/en/select-into.html](https://dev.mysql.com/doc/refman/8.4/en/select-into.html) guide for reference.

While debugging this; I also revisited the fundamentals of [what is pl sql](https://www.igmguru.com/blog/what-is-pl-sql) to better understand how MySQL’s procedural logic compares to Oracle’s. Any clarity on scoping / optimizer quirks with `SELECT INTO` would be very helpful especially in complex procedures with branching logic. 🤔

Thank you !! 🙂

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**Author:** ![kedarpercona](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/kedarpercona/32/809_2.png) [@kedarpercona](https://forums.percona.com/u/kedarpercona)\
**Post date:** [July 10, 2025, 10:17am UTC](https://forums.percona.com/t/why-select-into-fails-silently-inside-mysql-if-blocks-during-pl-sql-logic-migration/38623/2 "2025-07-10T10:17:31Z")

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Hi @benof ,  
Welcome to Percona Community. Would you be able to provide the procedure? That’d be easy to answer.

Thanks,  
Kedar

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**Author:** ![matthewb](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/matthewb/32/34_2.png) [@matthewb](https://forums.percona.com/u/matthewb)\
**Post date:** [July 10, 2025, 10:58pm UTC](https://forums.percona.com/t/why-select-into-fails-silently-inside-mysql-if-blocks-during-pl-sql-logic-migration/38623/3 "2025-07-10T22:58:36Z")

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Hello @benof, You will find that MySQL’s stored procedure language is rudimentary compared to PL/SQL from Oracle. It will not be a 1 to 1 conversion; some concessions will take place, and rewrites will happen as well.