Why Does My PreparedStatement Throw a Syntax Error Near \'?\': A Java MySQL Issue

PreparedStatement Syntax Error: '<' Expected

Encountering the "preparedStatement syntax error" while using Java PreparedStatements can be frustrating. If you're encountering the error:

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

with code like:

    String selectSql1
        = "SELECT `value` FROM `sampling_numbers` WHERE `value` < (?)" ;
    ResultSet rs1 = con.select1(selectSql1,randNum);

it's because you're incorrectly calling Statement.executeQuery(String) instead of PreparedStatement.executeQuery(). Here's how to fix it:

    this.stmt = con.prepareStatement(sql); // Prepares the Statement.
    stmt.setInt(1, randNum);               // Binds the parameter.
    // return this.stmt.executeQuery(sql); // calls Statement#executeQuery
    return this.stmt.executeQuery();       // calls your prepared PreparedStatement

By changing this line, you'll correctly execute the PreparedStatement and avoid the "preparedStatement syntax error."

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