BEGIN TRANSACTION syntax in SQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to start a transaction in SQL.

SQL

[1];

Drag options to blanks, or click blank then click option'

ACOMMIT TRANSACTION

BBEGIN TRANSACTION

CROLLBACK TRANSACTION

DSAVE TRANSACTION

Attempts:

3 left

💡 Hint

Common Mistakes

Using COMMIT TRANSACTION to start a transaction.

Using ROLLBACK TRANSACTION instead of BEGIN TRANSACTION.

The BEGIN TRANSACTION statement starts a new transaction block in SQL.

2fill in blank

medium

Complete the code to start a transaction and ensure changes can be undone if needed.

SQL

[1]; -- start transaction

Drag options to blanks, or click blank then click option'

ACOMMIT TRANSACTION

BSAVE TRANSACTION

CROLLBACK TRANSACTION

DBEGIN TRANSACTION

Attempts:

3 left

💡 Hint

Common Mistakes

Using SAVE TRANSACTION to start a transaction.

Using COMMIT TRANSACTION at the start.

BEGIN TRANSACTION starts the transaction so changes can be committed or rolled back later.

3fill in blank

hard

Fix the error in this SQL code that tries to start a transaction.

SQL

BEGIN [1];

Drag options to blanks, or click blank then click option'

AROLLBACK

BCOMMIT

CTRANSACTION

DSAVE

Attempts:

3 left

💡 Hint

Common Mistakes

Using BEGIN COMMIT instead of BEGIN TRANSACTION.

Using BEGIN ROLLBACK which is invalid.

The correct syntax to start a transaction is BEGIN TRANSACTION.

4fill in blank

hard

Fill both blanks to correctly start and then commit a transaction.

SQL

[1];
-- some SQL statements
[2];

Drag options to blanks, or click blank then click option'

ABEGIN TRANSACTION

BCOMMIT TRANSACTION

CROLLBACK TRANSACTION

DSAVE TRANSACTION

Attempts:

3 left

💡 Hint

Common Mistakes

Using ROLLBACK TRANSACTION instead of COMMIT TRANSACTION to save changes.

Not starting with BEGIN TRANSACTION.

First, start the transaction with BEGIN TRANSACTION. After your SQL statements, use COMMIT TRANSACTION to save changes.

5fill in blank

hard

Fill all three blanks to start a transaction, create a savepoint, and then rollback to it.

SQL

[1];
SAVEPOINT [2];
ROLLBACK TO [3];

Drag options to blanks, or click blank then click option'

ABEGIN TRANSACTION

Bsp1

DCOMMIT TRANSACTION

Attempts:

3 left

💡 Hint

Common Mistakes

Using different names for savepoint and rollback.

Using COMMIT TRANSACTION instead of BEGIN TRANSACTION at start.

Start with BEGIN TRANSACTION. Then create a savepoint named sp1. Finally, rollback to that savepoint using its name.

Practice

1. What is the main purpose of using BEGIN TRANSACTION in SQL?

easy

A. To permanently delete all data from a table

B. To start a group of database operations that can be saved or undone together

C. To create a new database

D. To display all records from a table

Solution

1. Step 1: Understand what BEGIN TRANSACTION does

   This command starts a transaction, grouping multiple operations so they can be committed or rolled back as one.

2. Step 2: Compare other options

   Deleting data, creating databases, or displaying records are unrelated to starting transactions.

3. Final Answer:

   To start a group of database operations that can be saved or undone together -> Option B

4. Quick Check:

   BEGIN TRANSACTION = start safe group [OK]

Hint: Think of transactions as a safety net for multiple actions [OK]

Common Mistakes:

• Confusing transaction start with data deletion
• Thinking it creates databases
• Assuming it shows data

2. Which of the following is the correct syntax to start a transaction in SQL?

easy

A. BEGIN TRANSACTION;

B. START TRANSACTION;

C. BEGIN;

D. TRANSACTION START;

Solution

1. Step 1: Recall standard SQL syntax for starting transactions

   The correct syntax to start a transaction is BEGIN TRANSACTION;.

2. Step 2: Check other options for correctness

   START TRANSACTION; is valid in some systems but not standard SQL; BEGIN; alone is incomplete; TRANSACTION START; is invalid syntax.

3. Final Answer:

   BEGIN TRANSACTION; -> Option A

4. Quick Check:

   Correct syntax = BEGIN TRANSACTION; [OK]

Hint: Remember: 'BEGIN TRANSACTION;' starts the safe block [OK]

Common Mistakes:

• Using incomplete 'BEGIN;' without TRANSACTION
• Confusing order of words
• Using non-standard phrases

3. Consider this SQL code:

BEGIN TRANSACTION;
UPDATE accounts SET balance = balance - 100 WHERE id = 1;
UPDATE accounts SET balance = balance + 100 WHERE id = 2;
COMMIT;

What is the effect of this transaction?

medium

A. The transaction will cause an error

B. Only the first update is saved

C. Both updates happen together or not at all

D. Updates happen immediately without grouping

Solution

1. Step 1: Analyze the transaction block

   The two updates are inside a transaction started by BEGIN TRANSACTION; and ended by COMMIT;.

2. Step 2: Understand transaction behavior

   Both updates will be saved together if no errors occur; if an error happens, none will be saved.

3. Final Answer:

   Both updates happen together or not at all -> Option C

4. Quick Check:

   Transaction = all or nothing [OK]

Hint: Transactions group changes to save or cancel together [OK]

Common Mistakes:

• Thinking updates save separately
• Assuming immediate save without commit
• Believing transaction causes error here

4. Identify the error in this SQL transaction code:

BEGIN TRANSACTION
INSERT INTO users (name) VALUES ('Alice');
COMMIT;

medium

A. INSERT statement is invalid

B. COMMIT should come before INSERT

C. No error, code is correct

D. Missing semicolon after BEGIN TRANSACTION

Solution

1. Step 1: Check syntax of each statement

   BEGIN TRANSACTION is missing a semicolon at the end, which is required to separate statements.

2. Step 2: Verify order and validity of other statements

   COMMIT; correctly comes after the insert; the insert syntax is valid.

3. Final Answer:

   Missing semicolon after BEGIN TRANSACTION -> Option D

4. Quick Check:

   Semicolon needed after BEGIN TRANSACTION [OK]

Hint: Always end SQL statements with semicolon [OK]

Common Mistakes:

• Forgetting semicolon after BEGIN TRANSACTION
• Misordering COMMIT and INSERT
• Assuming insert syntax is wrong

5. You want to transfer $200 from account A (id=1) to account B (id=2) safely. Which SQL transaction block correctly ensures the transfer is atomic and consistent?

hard

A. BEGIN TRANSACTION;
UPDATE accounts SET balance = balance - 200 WHERE id = 1;
UPDATE accounts SET balance = balance + 200 WHERE id = 2;
COMMIT;

B. UPDATE accounts SET balance = balance - 200 WHERE id = 1;
UPDATE accounts SET balance = balance + 200 WHERE id = 2;

C. BEGIN TRANSACTION;
UPDATE accounts SET balance = balance + 200 WHERE id = 2;
COMMIT;

D. BEGIN;
UPDATE accounts SET balance = balance - 200 WHERE id = 1;
ROLLBACK;

Solution

1. Step 1: Understand the need for atomic transfer

   Both debit and credit updates must happen together or not at all to keep balances consistent.

2. Step 2: Evaluate each option

   BEGIN TRANSACTION;
   UPDATE accounts SET balance = balance - 200 WHERE id = 1;
   UPDATE accounts SET balance = balance + 200 WHERE id = 2;
   COMMIT;

   uses BEGIN TRANSACTION and COMMIT to group both updates safely.

   UPDATE accounts SET balance = balance - 200 WHERE id = 1;
   UPDATE accounts SET balance = balance + 200 WHERE id = 2;

   lacks transaction, risking partial update.

   BEGIN TRANSACTION;
   UPDATE accounts SET balance = balance + 200 WHERE id = 2;
   COMMIT;

   only credits without debit.

   BEGIN;
   UPDATE accounts SET balance = balance - 200 WHERE id = 1;
   ROLLBACK;

   rolls back, so no change occurs.

3. Final Answer:

   BEGIN TRANSACTION;
   UPDATE accounts SET balance = balance - 200 WHERE id = 1;
   UPDATE accounts SET balance = balance + 200 WHERE id = 2;
   COMMIT;

   -> Option A

4. Quick Check:

   Atomic transfer needs BEGIN TRANSACTION + COMMIT [OK]

Hint: Use BEGIN TRANSACTION and COMMIT to group related updates [OK]

Common Mistakes:

• Not grouping both updates in a transaction
• Forgetting COMMIT to save changes
• Rolling back changes unintentionally