[英]How do I retrieve a single cell from MySQL database using query and assigned it to a variable in Java Netbeans Apache
首先,我將嘗試使用查詢來使用項目描述檢索 int min_stock 單個單元格。 然后將該值放入變量中。 我希望能夠讓變量 minStock 等於一個數字。 我想用它在我的程序中進行操作。
PreparedStatement cm = con.prepareStatement(checkMinimumStock);
ResultSet minS = cm.executeQuery("SELECT min_stock FROM items WHERE item_description = '"+item+"'");
int minStock = minS.getInt("min_stock");```
您選擇了錯誤的方式來使用PrepareStatment
。
你有兩個選擇:
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);
接着
if (rs.next())
int minStock = rs.getInt("min_stock");
else
//not found any match row in DB table
嘗試這個
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");
}
String checkMinimumStock = "SELECT min_stock FROM items WHERE item_description =? ";
忘記在代碼開頭添加這個了!
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