PreparedStatement使用注意

Java代码

1. String sql = "SELECT value from user where" + "`" + idField + "`" + "=?";
2. st = (PreparedStatement) connection.prepareStatement(sql);
3. st.setString(1, "0001");
4. rs = st.executeQuery(sql);//此处会报错！

String sql = "SELECT value from user where" + "`" + idField + "`" + "=?";st = (PreparedStatement) connection.prepareStatement(sql);st.setString(1, "0001");rs = st.executeQuery(sql);//此处会报错！

mysql报错如下：
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

解决办法：
将rs = st.executeQuery(sql)改为rs = st.executeQuery()