MySQL raises error 1327 when a stored program references a variable that has not been declared in its scope.
MySQL Error 1327: ER_SP_UNDECLARED_VAR appears when a stored procedure, function, trigger, or event refers to a variable that was never declared in DECLARE statements or parameter lists. Add or correct the DECLARE line, or rename the reference, to clear the error.
Undeclared variable: %s
Error 1327 occurs when MySQL executes a stored procedure, function, trigger, or event that references a variable not declared within the routine scope.
The SQL interpreter halts execution and returns SQLSTATE 42000 along with the message “Undeclared variable: var_name”.
A misspelled variable name prevents MySQL from matching the identifier with any declared variable, leading to the undeclared variable error.
Referencing a variable before its DECLARE statement can trigger the error because MySQL requires variables to be declared at the top of a block.
Copy-pasting code between routines without updating parameter or local variable lists is a frequent cause.
Declare the missing variable using a correct DECLARE statement placed before any executable statement.
If the variable already exists, rename either the declaration or the reference so they match exactly, respecting letter case.
For global session variables, prefix the name with @@ or include them in the parameter list rather than treating them as local variables.
While creating procedures that build dynamic SQL, engineers often forget to DECLARE sql_text VARCHAR(1000); Adding this line resolves the error.
In AFTER UPDATE triggers, using OLD.some_col as a standalone variable without aliasing causes Error 1327. Use NEW or OLD prefixed columns correctly.
Place all DECLARE statements immediately after BEGIN to guarantee scope visibility before use.
Adopt consistent naming conventions and static code analysis to flag undeclared identifiers during development.
Leverage Galaxy’s linting in its SQL editor to highlight undeclared variables in real time, preventing the error before deployment.
Error 1338 ER_SP_VARCOND_AFTER_CURSHNDLR arises when DECLARE statements appear after executable statements; move the DECLARE lines upward.
Error 1337 ER_SP_BADSELECT occurs when SELECT ... INTO violates variable count; ensure the number of target variables equals selected columns.
A single character mismatch between reference and declaration causes MySQL to treat the identifier as undeclared.
MySQL only scans DECLARE statements at the start of a block. Later declarations are ignored, resulting in undeclared status.
Developers sometimes reference an input parameter they forgot to include in the CREATE PROCEDURE parameter list.
Using a session variable name without @@ makes MySQL look for a local variable, which is not declared.
Raised when SELECT ... INTO has mismatched column and variable counts.
Occurs when DECLARE statements appear after executable statements or handlers.
Indicates cursor declarations placed after condition or handler declarations.
Yes. MySQL treats variable identifiers as case sensitive within stored programs. A mismatch in case leads to Error 1327.
Yes, but you must use the @@ prefix (e.g., @@session.var_name). Without the prefix, MySQL assumes a local variable.
Moving executable code above DECLARE statements hides the declarations from the parser. Restore DECLARE lines to the top of the block.
Galaxy’s editor highlights undefined identifiers in real time and suggests DECLARE snippets, reducing runtime errors.
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