我有一个表结构为,
Table 3
Fruit ID - Foreign Key (Primary Key of Table 1)
Crate ID - Foreign Key (Primary Key of Table 2)
现在我需要执行一个查询,
更新 箱子 ID
of 水果 ID
如果 水果 ID
已经在表中,如果没有则在表3中插入记录作为新记录。
这就是我现在在代码中得到的内容,
private void RelateFuirtWithCrates(List<string> selectedFruitIDs, int selectedCrateID)
{
string insertStatement = "INSERT INTO Fruit_Crate(FruitID, CrateID) Values " +
"(@FruitID, @CrateID);"; ?? I don't think if it's right query
using (SqlConnection connection = new SqlConnection(ConnectionString()))
using (SqlCommand cmd = new SqlCommand(insertStatement, connection))
{
connection.Open();
cmd.Parameters.Add(new SqlParameter("@FruitID", ????? Not sure what goes in here));
cmd.Parameters.Add(new SqlParameter("@CrateID",selectedCrateID));
}
最佳答案
您可以在 SQL Server 中使用 MERGE
语法执行“更新插入”:
MERGE [SomeTable] AS target
USING (SELECT @FruitID, @CrateID) AS source (FruitID, CrateID)
ON (target.FruitID = source.FruitID)
WHEN MATCHED THEN
UPDATE SET CrateID = source.CrateID
WHEN NOT MATCHED THEN
INSERT (FruitID, CrateID)
VALUES (source.FruitID, source.CrateID);
否则,您可以使用类似以下内容:
update [SomeTable] set CrateID = @CrateID where FruitID = @FruitID
if @@rowcount = 0
insert [SomeTable] (FruitID, CrateID) values (@FruitID, @CrateID)
关于c# - 如何更新 SQL 表逻辑,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/16539315/