Why Does My Prepared Statement in MySQL JDBC Throw a \"MySQLSyntaxErrorException\"?

MySQL Prepared Statement: Overcoming the "MySQLSyntaxErrorException" Error

When utilizing prepared statements in JDBC for MySQL, it's essential to ensure proper syntax and usage. One common error faced by developers is the "MySQLSyntaxErrorException." Let's explore a specific instance of this error and the corresponding solution.

Problem:

A Java-based application using the MySQL connector experiences a "MySQLSyntaxErrorException" when executing a prepared statement. The code uses the following statement for data retrieval:

<code class="java">PreparedStatement stmt = con.prepareStatement(selectSQL);
stmt.setInt(1, ad_id);
rs = stmt.executeQuery(selectSQL);</code>

Upon execution, the error is thrown.

Error Message:

com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '?' at line 1

Solution:

The error lies within the syntax of executing the prepared statement. Specifically, the following line is incorrect:

<code class="java">rs = stmt.executeQuery(selectSQL);</code>

The correct syntax for executing a prepared statement is:

<code class="java">rs = stmt.executeQuery();</code>

By omitting the selectSQL argument from the executeQuery method, the statement is executed correctly, and the error is resolved.

Explanation:

In a prepared statement, the SQL query is passed during statement preparation, and the parameters are set separately using the setX methods (e.g., setInt). The executeQuery method is used to fetch the result set, which should be called without any arguments. The original code incorrectly included the SQL query string in the executeQuery method call, causing the syntax error.

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