MySQL error 1309 occurs when a stored program tries to declare or use a label name that has already been defined in the same scope.
MySQL Error 1309: ER_SP_LABEL_REDEFINE appears when a stored procedure, function, trigger, or event reuses a label already declared in the current scope. Give each LOOP, BEGIN…END, or handler a unique label name or drop the duplicate block to resolve the error.
Redefining label %s
Error 1309 fires during compilation of a stored procedure, function, trigger, or event when MySQL detects that a label name is defined more than once in the same scope. Labels identify control-flow blocks such as LOOP, REPEAT, WHILE, or BEGIN…END, and they must be unique within their block level.
The server stops parsing at the duplicate declaration and aborts creation or execution of the routine, returning SQLSTATE 42000.
Duplicate labels prevent the routine from compiling, halting deployment pipelines and blocking application features that depend on the affected stored program. Resolving the error restores normal database behavior and CI/CD workflows.
Reusing a label name inside the same BEGIN…END block is the primary trigger. Copy-pasting code, refactoring loops, or merging branches without renaming labels often introduces the duplication.
Nesting a block that accidentally shares the parent label, or declaring an EXIT or CONTINUE handler label identical to an existing loop label, also raises error 1309.
Identify every label in the routine and ensure each is unique within its scope. Rename duplicates or delete obsolete blocks. Run the corrected CREATE PROCEDURE or ALTER PROCEDURE statement to recompile successfully.
Adopt a label naming convention such as prefixing with the block purpose (e.g., l_fetch_users). Use code linters or Galaxy’s real-time syntax checker to highlight duplicates while typing. Keep stored programs in version control so code reviews catch naming collisions early.
Galaxy’s IDE instantly flags duplicate labels as you write or paste SQL, offers AI-powered fixes, and enforces code reviews through Collections. These tools reduce human error and speed up routine development.
Two LOOP or BEGIN blocks inside the same parent block share the exact label name.
A DECLARE CONTINUE or EXIT handler is given the same label as an existing block label.
Developers duplicate code fragments without updating internal label names, leading to collisions.
Raised when an END label does not match its BEGIN label. Ensure labels are identical.
Occurs when a stored procedure is called with more arguments than declared.
Triggered when referencing a stored routine that has not been created.
Yes. Labels must be unique only within the same scope. Nested blocks may reuse names that are not visible to their parent.
No. Labels are compile-time identifiers and have no runtime overhead, so renaming them has zero performance impact.
The error exists in all supported MySQL versions 5.1 and later. Behavior is consistent across versions.
The Galaxy SQL editor underlines duplicate labels in red and provides an AI suggestion to automatically rename or remove the offending block.
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