mysql-best-practices

MySQL Best Practices

When to Apply

Use this skill when:

• The user asks to read or modify MySQL data through this plugin MCP.
• The task touches tables, columns, relations, users, or schema design.
• The agent is about to run insert_row, update_rows, delete_rows, create_table, drop_table, add_column, or drop_column.
• The user is troubleshooting connection, permissions, or external-host access.

Core Rules

1. Prefer inspection before mutation.

   • Before writing rows, inspect the target table with describe_table.
   • Before schema changes, inspect relations with inspect_table_relationships or inspect_database_schema.

2. Read-first by default.

   • Prefer list_tables, describe_table, select_rows, and resources such as mysql://schema/{database} before changing data.
   • Treat MCP_WRITE_MODE=read-only as the safe default.

3. Do not perform destructive operations without explicit user intent.

   • delete_rows, drop_table, and drop_column require clear confirmation.
   • When deleting or dropping, first identify what will be affected.

4. Verify every write.

   • After insert_row, read the inserted row back when possible.
   • After update_rows or delete_rows, confirm affected rows and re-check the table state.
   • After schema changes, re-run describe_table or schema inspection.

5. Match existing data conventions.

   • Reuse existing column naming and type patterns.
   • For auth or user tables, inspect current password storage before inserting credentials. If existing rows use hashes, do not insert plaintext passwords.

6. Protect identifiers and scope.

   • Use only known database, table, and column names from schema inspection.
   • Prefer operating on the configured default database unless the user explicitly names another one.

Schema Change Workflow

For table or column changes, follow this order:

1. Inspect the current table and relationships.
2. Check whether a foreign key, unique index, or application expectation depends on the target column or table.
3. Apply the smallest safe change.
4. Verify the final schema.