In the previous video, we created a transaction…to transfer money from one account to another.…But there was nothing to prevent the transaction from…going ahead if the payer ran out of funds.…This is pdo_check_balance.php which…you can find in the Chapter 3, 03_07 folder of the exercise files.…The script has been updated to roll back the transaction…if the balance in the outgoing account falls below zero.…Adding this extra step results in some databases displaying…the wrong balance after the transaction has been rolled back.…
The fix is very easy but first let's take…a look at the code and see what's happening.…On line nine is a new prepared statement with a named…placeholder that gets the balance from the savings account for the payer.…Then on lines 16 and 17 the statement is prepared…and the payer's name is bound to the named placeholder.…The third statement is executed a bit further down, here on line 31.…And then, on line 32, the fetchColumn method is used to get the result.…
There's only one result.…So that's used to get it and it's assigned bal.…
Author
David Powers
Released
7/7/2014- Connecting to a database with PDO or MySQLi
- Fetching a result set
- Executing simple non-SELECT queries
- Sanitizing user input
- Binding input and output values
- Passing an array of values to the execute() method
- Working with advanced PDO fetch methods
- Executing a MySQLi transaction
- Freeing resources that are no longer needed
- Submitting multiple queries
- Creating an instance of a class from a result set
Skill Level Intermediate
Duration
Views
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Introduction
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Welcome1m
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Using the exercise files4m 56s
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Setting SQLite permissions1m 11s
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1. Why Use Object-Oriented PHP to Access a Database?
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Using prepared statements4m 24s
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Using transactions1m 43s
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2. PHP Data Object (PDO) Basics
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Fetching a result set8m 3s
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Getting error messages7m 17s
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3. PDO-Prepared Statements and Transactions
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Using named parameters9m 51s
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Binding results to variables7m 53s
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Executing a transaction6m 54s
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4. Advanced PDO Fetch Methods
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Reusing a result set7m 53s
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5. MySQL Improved Basics
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Setting the character set1m 57s
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Fetching the result7m 35s
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Handling non-SELECT queries5m 27s
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Getting error messages5m 47s
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6. MySQLi Prepared Statements and Transactions
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Binding output variables5m 6s
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7. Diving Deeper into MySQLi
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Using real_query()6m 1s
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Submitting multiple queries6m 41s
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Conclusion
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PDO and MySQLi compared3m 31s
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Video: Closing the cursor before running another query