What are the results of the following SQL commands if col is an integer column?

1. SELECT * FROM mytbl WHERE num_col = '4';
2. SELECT * FROM mytbl WHERE num_col = 4;

Solution (By Examveda Team)

This question tests your understanding of how MySQL handles data types in comparisons. Let's break it down:

Understanding the Code:
Both SQL statements are trying to select data from a table named 'mytbl' where the column 'num_col' matches a specific value.

Key Difference:
The difference lies in how the value is written:
* Statement 1: `SELECT * FROM mytbl WHERE num_col = '4';` uses single quotes around the number '4'. This means MySQL treats '4' as a string, not an integer.
* Statement 2: `SELECT * FROM mytbl WHERE num_col = 4;` uses no quotes. This means MySQL treats 4 as an integer.

How MySQL Handles Data Types
MySQL is quite flexible in how it handles data types during comparisons. When you compare a string to an integer, MySQL will attempt to implicitly convert the string to an integer. This is done by removing any leading or trailing spaces and then trying to interpret the string as a number.

The Answer:
If 'num_col' is an integer column, both statements will likely produce the same results. MySQL will implicitly convert '4' (string) to 4 (integer) in the first statement, allowing the comparison to work correctly.

Therefore, the answer is Option A: same.

Important Note: While this will often work, it's best practice to always use the correct data type when comparing values. Using the appropriate data type ensures consistency and avoids potential errors in cases where implicit conversions might not be successful.