java - 带有PreparedStatement的com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException

Question

我在 DAO 类中有以下代码:

public boolean employeeExists(String employeeCode) throws InstantiationException, SQLException {
    String SQL_TEXT = "select count(*) from employee where emp_code=?;";

    int scalarValue = 0;

    Connection conn = DatabaseAccess.getConnection();
    PreparedStatement pstmt = conn.prepareStatement(SQL_TEXT);
    pstmt.setString(1, employeeCode);

    try {
        ResultSet rs = pstmt.executeQuery(SQL_TEXT);
        if (rs.next()) {
            scalarValue = rs.getInt(1);
        }
    } catch (SQLException e) {
        // TODO: log error.
        throw e;
    } finally {
        if (pstmt != null && !pstmt.isClosed())
            pstmt.close();
        if (conn != null && !conn.isClosed())
            conn.close();
    }
    return scalarValue > 0;
}

当我运行代码，即调用上述 DAO 方法时，出现以下错误:

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 '?'

语法似乎没问题，并且可以在 mysql 工作台中执行，但使用 JDBC 会引发异常。 这是 mysql jdbc 驱动程序中的某种错误吗？请帮忙。

Answer 1

您的问题在于:- ResultSet rs = pstmt.executeQuery(SQL_TEXT);

将其更改为:- ResultSet rs = pstmt.executeQuery();