PreparedStatement Syntax Error: Why is my SQL query failing, and how can I fix it?

"PreparedStatement Syntax Error: Understanding the Issue and Solution"

In Java, when working with databases, using PreparedStatements is essential for preventing SQL injection attacks. However, sometimes, developers encounter a perplexing error: "preparedStatement syntax error."

This error can arise due to incorrect syntax in the SQL statement provided to the PreparedStatement. In the example mentioned, the SQL statement is:

String selectSql1
        = "SELECT `value` FROM `sampling_numbers` WHERE `value` < (?)" ;

Here, the issue lies in the use of a placeholder without proper syntax. To use a placeholder in a PreparedStatement, it must be followed by "?" (without quotes). The correct syntax would be:

String selectSql1
        = "SELECT `value` FROM `sampling_numbers` WHERE `value` < ?" ;

Another common mistake that can lead to this error is calling the wrong execute method. In the erroneous code, the developer has mistakenly used the Statement#executeQuery(String) method, which is not suitable for PreparedStatements. The correct method to use is PreparedStatement#executeQuery().

To summarize, the cause of the "preparedStatement syntax error" encountered is a combination of incorrect placeholder syntax and using the wrong execute method. By correcting these issues, the code will execute successfully and retrieve data from the database without SQL injection vulnerability.

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