当我从表格中的列中获取价值时，我的项目中有一个问题。我用c＃代码创建数据库。
这是我的代码：
public static int typeTransactionIncome = 1; // thu
public static int typeTransactionExpense = 2; // chi
public static int typeTransactionDebt = 3; // nợ
public static int typeTransactionLoan = 4; // cho vay
public static string tableNameCategory = "categories";
private static string createTableTransactionString = "CREATE TABLE IF NOT EXISTS \"transactions\" " + "(\"id\" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL ,"
+ "\"name\" VARCHAR(140) ," + "\"amount\" FLOAT NOT NULL DEFAULT (0) ," + "\"type\" INTEGER NOT NULL ,"
+ "\"created_date\" DATETIME NOT NULL DEFAULT (CURRENT_DATE) ," + "\"displayed_date\" DATETIME NOT NULL DEFAULT (CURRENT_DATE) ,"
+ "\"cat_id\" INTEGER NOT NULL DEFAULT (0) ," + "\"with_person\" VARCHAR(50)," + "\"remind_date\" DATETIME,"
+ "\"remind_num\" INTEGER DEFAULT (0) ," + "\"note\" VARCHAR(140) ," + "\"status\" BOOL NOT NULL DEFAULT (0),"
+ "\"user_id\" INT NOT NULL DEFAULT (1))";
这是插入代码：插入一些列，然后有2个插入menthod
public void insertNewIncome(string _name, string _note, double _amount, DateTime _displayedDate, int _catId, int _usertId)
{
try
{
openConnection();
SqliteCommand cmd = conn.CreateCommand();
cmd.CommandText = "INSERT INTO " + tableNameTransaction + "(type, name, note, amount, displayed_date, cat_id, user_id) values (@type, @name, @note, @amount, @displayed_date, @cat_id, @user_id)";
cmd.Parameters.Add("@type", typeTransactionIncome);
cmd.Parameters.Add("@name", _name);
cmd.Parameters.Add("@note", _note);
cmd.Parameters.Add("@amount", _amount);
cmd.Parameters.Add("@displayed_date", _displayedDate);
cmd.Parameters.Add("@cat_id", _catId);
cmd.Parameters.Add("@user_id", _usertId);
cmd.ExecuteNonQuery();
//MessageBox.Show("income");
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
finally
{
closeConnection();
}
}
public void insertNewDebt(string _debter, string _note, double _amount, DateTime _ngay_vay, DateTime _ngay_tra, int _user_id)
{
try
{
openConnection();
SqliteCommand cmd = conn.CreateCommand();
cmd.CommandText = "INSERT INTO " + tableNameTransaction + "(type, with_person, note, amount, displayed_date, remind_date, user_id) VALUES (@type, @with_person, @note, @amount, @displayed_date, @remind_date, @user_id)";
cmd.Parameters.Add("@type", typeTransactionDebt);
cmd.Parameters.Add("@with_person", _debter);
cmd.Parameters.Add("@note", _note);
cmd.Parameters.Add("@amount", _amount);
cmd.Parameters.Add("@displayed_date", _ngay_tra);
cmd.Parameters.Add("@remind_date", _ngay_tra);
cmd.Parameters.Add("@user_id", _user_id);
cmd.ExecuteNonQuery();
//MessageBox.Show("debt");
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}
finally
{
closeConnection();
}
}
我是通过insertNewDebt和insertNewIncome menthod将一些记录插入到表中，没关系，没有任何错误。
这是获得表中所有记录的方法：
public List<ItemTransaction> loadTransactionAll(DateTime _start_date, DateTime _end_date, int _user_id)
{
List<ItemTransaction> li = new List<ItemTransaction>();
openConnection();
SqliteCommand cmd = conn.CreateCommand();
cmd.CommandText = "SELECT transactions.id AS master_id,transactions.name,transactions.amount,transactions.type,transactions.created_date, transactions.displayed_date,transactions.cat_id, transactions.with_person,transactions.remind_date,remind_num, transactions.note,transactions.status,transactions.user_id,categories.id,categories.name,categories.icon,categories.type,IFNULL(sub_amount,0) AS sub_amount "
+ "FROM transactions "
+ "LEFT JOIN categories ON transactions.cat_id = categories.id "
+ "LEFT JOIN ("
+ "SELECT sub_trans_id, IFNULL(SUM(sub_amount),0) AS sub_amount "
+ "FROM (SELECT trans_id AS sub_trans_id,SUM(amount) AS sub_amount "
+ "FROM sub_transactions "
+ "WHERE type = @type_income "
+ "GROUP BY sub_trans_id "
+ "UNION ALL SELECT trans_id AS sub_trans_id,SUM(amount) * -1 AS sub_amount "
+ "FROM sub_transactions "
+ "WHERE type = @type_expense GROUP BY sub_trans_id) GROUP BY sub_trans_id) ON sub_trans_id = master_id "
+ "WHERE (displayed_date BETWEEN @start_date AND @end_date) "
+ "AND transactions.user_id = @user_id "
+ "ORDER BY displayed_date DESC, transactions.type ASC, status ASC";
cmd.Parameters.Add("@type_income", DatabaseProccess.typeTransactionIncome);
cmd.Parameters.Add("@type_expense", DatabaseProccess.typeTransactionExpense);
cmd.Parameters.Add("@start_date", _start_date);
cmd.Parameters.Add("@end_date", _end_date);
cmd.Parameters.Add("@user_id", _user_id);
SqliteDataReader reader = cmd.ExecuteReader();
while (reader.Read())
{
ItemTransaction item = new ItemTransaction();
item.master_id = reader.GetInt32(0);
item.name = reader.GetString(1);
item.amount = reader.GetDouble(2);
item.type = reader.GetInt32(3);
item.created_date = reader.GetDateTime(4);
item.displayed_date = reader.GetDateTime(5);
item.cat_id = reader.GetInt32(6);
item.with_person = reader.GetString(7);
item.remind_date = reader.GetDateTime(8);
item.remind_num = reader.GetInt32(9);
item.note = reader[10].ToString();
item.status = reader.GetBoolean(11);
item.user_id = reader.GetInt32(12);
item.setCategory(reader.GetInt32(13), reader.GetString(14), reader.GetString(15), reader.GetInt32(16));
item.sub_amount = reader.GetDouble(17);
li.Add(item);
}
return li;
}
但是当我执行insert：
时insertNewIncome("", "note", "1000", DateTime.Today, 1, 1);
使用'name'字段值=“”
我无法读取'name'字段。调试说：
view error screen shot here, please
这是ItemTransaction类：
view ItemTransaction class here, please
我不明白这个错误。
拜托，谢谢
答案 0 :(得分：0)
您收到此错误是因为name为NULL。
以下if语句将解决此问题：
if (reader(1) != null){
item.name = reader.GetString(1);
}
但是，如果您传递的值为""，则不应将其存储为NULL。
检查您的数据库并查看其值。也许您有一个触发器可以将""更新为null。