Database Interaction GPYC Practice Questions (Page 6)

Questions 26–30

1. 26application · medium

   A Python script connects to a remote MySQL server. The connection attempt fails because the server is temporarily unreachable. The script should retry the connection a few times before giving up. Which pattern is most appropriate?

   • AWrap the connection call in a try/except and retry with a short sleep in a loop.
   • BUse a context manager to automatically close the connection on failure.
   • CSet the connection timeout to a very high value and wait indefinitely.
   • DCall connection.ping() before each query and reconnect if it fails.
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2. 27application · medium

   A Python script transfers funds between two bank accounts in a MySQL database. The script performs a SELECT to check the balance, an UPDATE to debit one account, and an UPDATE to credit the other. If the second UPDATE fails, what must the script do to maintain data integrity?

   • ACall rollback() to undo the first UPDATE and any other changes in the transaction.
   • BCall fetchall() to retrieve the error and continue with the next transaction.
   • CCall commit() to save the first UPDATE and then retry the second UPDATE.
   • DCall close() on the cursor to automatically undo the failed statement.
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4. 28foundation · easy

   Which cursor method is used to execute a SQL SELECT statement in Python's DB-API?

   • Aexecute()
   • Brun()
   • Cfetch()
   • Dquery()
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5. 29foundation · easy

   Which Python keyword is used to catch an exception so that the program can handle it gracefully?

   • Aexcept
   • Bfinally
   • Ctry
   • Dthrow
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6. 30application · medium

   A team is building a new Python service that must support both PostgreSQL and SQLite for development and production environments. They want to write the data access layer once and switch databases with minimal code changes. Which tool should they choose?

   • AUse psycopg2 directly for PostgreSQL and sqlite3 for SQLite, with separate code paths.
   • BUse SQLAlchemy Core with a dialect that supports both databases.
   • CUse a custom abstraction layer that wraps both drivers.
   • DUse raw SQL with standard syntax that works on both databases.
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