我正在尝试自动生成发票号,并在 Oracle sql db 中创建了名为 Product 的表,当我从后端表检查最大值为 103 时,但是当我使用此代码执行操作时,我收到错误:
java.lang.NumberFormatException: null
表格描述为
ID NUMBER(4),
MANUF_NAME VARCHAR2(20)
它已经有3条记录,最高ID号是103,现在我必须得到104,但没有得到
public void InvoiceNo ()
{
try {
connection2database();
Statement st = con.createStatement();
ResultSet rs = st.executeQuery("select MAX(ID) from PRODUCT");
if (rs.next())
{
int invoicenumber = Integer.parseInt(rs.getString(1))+1;
jLabel2.setText(Integer.toString(invoicenumber));
}
}
catch (Exception Ex)
{
Ex.printStackTrace();
JOptionPane.showMessageDialog(this, Ex.toString());
}
}
最佳答案
public void InvoiceNo ()
{
try {
connection2database();
Statement st = con.createStatement();
/* While getting value from DB do +1*/
ResultSet rs = st.executeQuery("select MAX(ID)+1 from PRODUCT");
if (rs.next())
{
jLabel2.setText(Integer.toString(rs.getInt(1)));
}
}
catch (Exception Ex)
{
Ex.printStackTrace();
JOptionPane.showMessageDialog(this, Ex.toString());
}
}
希望这会起作用。
关于java.lang.NumberFormatException : null error in java while generating invoice number from oracle db,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/61349127/