c# mysql incrementing null 错误

Question

我正在更新一个 mysql 数据库，即使值设置为 0，我也会收到一个奇怪的错误。

我试着运行这个:

MySqlCommand update = new MySqlCommand("UPDATE email_batch SET numberOfSendAttempts = numberOfSendAttempts + 1 AND sentOn = @sentOn WHERE outputFolder = @outputFolder", conn);
update.Parameters.AddWithValue("@sentOn", DateTime.Now);
update.Parameters.AddWithValue("@outputFolder", outputFolder);
update.ExecuteNonQuery();

但是我得到了这个错误

Exception has occurred: CLR/MySql.Data.MySqlClient.MySqlException
An unhandled exception of type 'MySql.Data.MySqlClient.MySqlException' occurred in MySql.Data.dll: 'Column 'numberOfSendAttempts' cannot be null'
   at MySql.Data.MySqlClient.MySqlStream.ReadPacket()
   at MySql.Data.MySqlClient.NativeDriver.GetResult(Int32& affectedRow, Int64& insertedId)
   at MySql.Data.MySqlClient.Driver.NextResult(Int32 statementId, Boolean force)
   at MySql.Data.MySqlClient.MySqlDataReader.NextResult()
   at MySql.Data.MySqlClient.MySqlCommand.ExecuteReader(CommandBehavior behavior)
   at MySql.Data.MySqlClient.MySqlCommand.ExecuteNonQuery()
   at emailBatchReader.emailBatchReader.Main(String[] args) in C:\Users\tpaolini\Desktop\sendEmailBatch\emailBatchReader.cs:line 332

我知道发生这种情况是因为我将值设置为非空，但应该将其设置为递增 1。我检查了我的 mysql 语法，这似乎是正确的，我在没有递增语句的情况下检查了它并且它有效。我的声明试图使该值为空怎么办？

Answer 1

您需要使用 comma's分隔要设置的字段，而不是 AND

UPDATE email_batch
SET numberOfSendAttempts = numberOfSendAttempts + 1, sentOn = @sentOn
WHERE outputFolder = @outputFolder