当新值是局部变量时，SQL UPDATE 的语法是什么 [重复]

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

更新命令文本如下 -

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;