Can MySQLi's `multi_query` Function Execute Multiple SQL Statements Safely and Efficiently?

Performing Multiple SQL Statements in a Single mysql_query() Call

Performing multiple SQL statements in a single call to the mysql_query() function can be a useful technique for certain scenarios. For instance, consider the task of updating two fields in a table, one named "name" to the value 'bob' and another named "age" to the value 55, with the condition that the corresponding "name" field is set to 'jim'.

The deprecated mysql_query() function cannot directly handle multiple SQL statements within a single call. However, there is an alternative approach using the mysqli::multi_query method, which can execute multiple SQL statements sequentially in the same call.

Using mysqli::multi_query

To perform multiple SQL statements using mysqli::multi_query, you can follow these steps:

1. Establish a connection to the database using mysqli_connect() or mysqli_init() and mysqli_real_connect().

2. Prepare the SQL statements to be executed. In this case, the statements might look like the following:

   • UPDATE table SET name = 'bob' WHERE name = 'jim'
   • UPDATE table SET age = 55 WHERE name = 'jim'
3. Execute the multiple SQL statements using mysqli::multi_query as follows:

$result = mysqli_multi_query($conn, $sqlStatement1."\n".$sqlStatement2);

Where:

• $conn is the established mysqli connection.
• $sqlStatement1 is the first SQL statement.
• $sqlStatement2 is the second SQL statement.

Caution:

While mysqli::multi_query provides a way to execute multiple SQL statements in a single call, it's important to note that it can introduce potential security vulnerabilities. By combining multiple statements, it can be easier for malicious actors to inject malicious code or perform unauthorized actions. Therefore, it's essential to exercise caution and implement proper input validation and security measures when using this method.

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