我正在尝试计算输入并将其与数据库中的数据字段进行匹配,然后计算状态并显示输入借来的图书数量。
Statement statement = conn.createStatement();
String sql = "SELECT COUNT(jtfMemberID.getText()) as num FROM LOAN WHERE LOAN_STATUS='BORROWED'";
ResultSet rs1 = statement.executeQuery(sql);
int personCount = 0;
if(rs1.next()) {
personCount = rs1.getInt("num");
jlbBookBorrow.setText(rs1.getString(personCount));
}else{
jlbBookBorrow.setText("0");
}
答案 0 :(得分:0)
文字jtfMemberID.getText()
将按照SQL
String
的字面解释。你需要把它解压出来:
String sql = "SELECT COUNT(" + jtfMemberID.getText() + ") as num FROM LOAN WHERE LOAN_STATUS='BORROWED'";
另外,为防止SQL Injection攻击,请考虑使用PreparedStatement。