事务->:事务是恢复和并发控制的基本单位
->事务具有四个特性：原子性、隔离性、一致性、持久性。这四个特性通常称为ACID
Begin transaction/tran --开始事务
Commit transaction/tran --提交事务
Rollback transaction/tran --回滚事务
Select * from userinfo with(nolock) --表示在查询的时候不加共享锁
一个简单的小案例
using (SqlConnection conn = new SqlConnection(connStr))
{
conn.Open();
//开始事务
SqlTransaction ts = conn.BeginTransaction();
try
{
string sql = "insert into BuyRecord(UID,PID,BRNum,BRTime) values(@uid,@pid,@num,@time)";
SqlCommand cmd = new SqlCommand(sql, conn);
cmd.Transaction = ts;
cmd.Parameters.AddWithValue("@uid", brm.UID);
cmd.Parameters.AddWithValue("@pid", brm.PID);
cmd.Parameters.AddWithValue("@num", brm.BRNum);
cmd.Parameters.AddWithValue("@time", DateTime.Now);
cmd.ExecuteNonQuery();
string uptsql = " update ProductInfo set ProductNum=ProductNum-@buyNum where ProductID=@id";
cmd.CommandText = uptsql;
cmd.Parameters.AddWithValue("@buyNum", brm.BRNum);
cmd.Parameters.AddWithValue("@id", brm.PID);
cmd.ExecuteNonQuery();
ts.Commit();
return 1;
}
catch (Exception)
{
ts.Rollback();
return -1;
throw;
}