Why Am I Getting MySQL Error 1005: 'Can't Create Table'?

Error Code 1005: Understanding 'Can't Create Table' Issue

When attempting to execute a database modification, Error Code 1005 may arise, accompanied by the message "Can't create table '...'" (errno: 150). This error prevents the creation of a new table or the modification of an existing one.

Identifying the Root Cause

The root cause of this error typically lies in incorrect primary key references. While solutions found online may not resolve the issue, there are several known causes that can trigger this error:

1. Mismatched Data Types or Size: Primary keys in different tables involved in a foreign key relationship must match exactly in data type and size. For instance, if one is declared as INT(10), the other must be INT as well, not BIGINT or SMALLINT.
2. Missing Index or Non-Primary Key: Foreign key-linked fields require a corresponding index or must be the primary key of the referenced table.
3. Duplicate Foreign Key Name: The name of the foreign key must be unique within the database. Consider adding unique identifiers to the foreign key name to rule out this possibility.
4. Incompatibility with MyISAM Tables: Foreign keys are not supported in MyISAM tables. Ensure that both tables involved in the relationship are using the InnoDB engine.
5. NOT NULL Constraint on Foreign Key Column: If a cascade ON DELETE SET NULL is specified, the foreign key column cannot be set to NOT NULL.
6. Charset and Collate Mismatches: The Charset and Collate attributes for primary keys must match at both table and field levels.
7. Default Value Restrictions: Avoid setting a default value (e.g., default=0) on a foreign key column.
8. Index Limitations: Key fields used in composite keys require individual indexes for foreign key references, even if they have indexes as part of the composite key.
9. Syntax or Naming Errors: Carefully review the ALTER statement for syntax errors or typos in field names.
10. Name Limit Exceeded: Foreign key names cannot exceed 64 characters in length.

Additional Resources

For further information on this specific error code, refer to the following resource:

• MySQL Error Number 1005 Can’t create table

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