当新值是局部变量时，SQL UPDATE的语法是什么

Question

在C＃Windows程序中，我想更新SQL Server表中的Int字段

int NewSeqno = MySeqno;    // get current sequence number

NewSeqno++;     // increment it

connection.Open();

// The following errors out saying that NewSeqno is not a column in the table.

// I want to update the field with the local variable NewSeqno.

command.CommandText = "UPDATE dbo.params SET NextSeqno = NewSeqno";

int recordsAffected = command.ExecuteNonQuery();

// The following statement, which writes a constant in the field, works fine.
command.CommandText = "UPDATE dbo.params SET NextSeqno = 123";

Answer 1

您必须将参数传递给SQL查询

如下更新命令文本-

command.CommandText = "UPDATE dbo.params SET NextSeqno = @NewSeqno";

添加此行以传递参数

command.Parameters.Add("@NewSeqno", SqlDbType.Int).Value = NewSeqno;