如何使用查询从 MySQL 数据库中检索单个单元格并将其分配给 Java Netbeans ZE9714F33DDD59 中的变量

Question

First I am going to try using query to retrieve the int min_stock single cell using the item description. Then put that value into a variable. I want to be able to have the variable minStock to be equal to a number. I want to use it to make operations in my program.

PreparedStatement cm = con.prepareStatement(checkMinimumStock);
ResultSet minS = cm.executeQuery("SELECT min_stock FROM items WHERE item_description = '"+item+"'"); 
            int minStock = minS.getInt("min_stock");```

Answer 1

you are choose wrong way to use PrepareStatment .
you have two option to do:

1:
String sql = "SELECT min_stock FROM items WHERE item_description =?";
PreparedStatement cm = con.prepareStatement(sql);
cm.setString(1, item);
ResultSet rs = cm.executeQuery();

2:
String sql = "SELECT min_stock FROM items WHERE item_description = '" + item + "'";
ResultSet rs = con.createStatement().executeQuery(sql);

and then

if (rs.next())
int minStock = rs.getInt("min_stock");
else
//not found any match row in DB table

Answer 2

Try this

String checkMinimumStock = "SELECT min_stock FROM items WHERE item_description = ? ";
PreparedStatement cm = con.prepareStatement(checkMinimumStock);
cm.setString(1,item);
ResultSet minS = cm.executeQuery();
if(minS.next()){
  int minStock = rs.getInt("min_stock");
}

Answer 3

String checkMinimumStock = "SELECT min_stock FROM items WHERE item_description =? ";

Forgot to add this in the beginning of the code!