sql - 锁定行以在 SQL Server 上读取？

Question

在 SQL 中，我想获取并删除符合特定条件的表的下一行。但是，我想防止其他服务执行相同的 SQL 位以返回相同的行。我在考虑事务或行锁，但看不出任何一个对我有什么帮助。

DECLARE @tblTempRow TABLE(intUserID int, intBlobID int)

-- Get the next match and remember in temp table. I want to prevent that other processes return the same row.
INSERT INTO @tblTempRow(intUserID, intBlobID)
SELECT TOP 1 intUserID, intBlobID FROM Schedule WHERE intScheduleType = @intScheduleType

-- Delete if requested.
IF(@intDeleteAfterGet = 1)
BEGIN
       DELETE FROM
        Schedule
    WHERE
        intUserID = (SELECT intUserID FROM @tblTempRow)
        AND intBlobID = (SELECT intBlobID FROM @tblTempRow)
                AND intScheduleType = @intScheduleType
END

-- Return the temp table.
SELECT intUserID, @intScheduleType, intBlobID FROM @tblTempRow

Answer 1

在这种情况下，您最好直接执行删除，并使用 OUTPUT clause填充您的表。那应该自动为您管理锁。 TODO:处理没有匹配的行，但你已经遇到了这个问题。

DECLARE @tblTempRow TABLE(intUserID int, intBlobID int)

IF(@intDeleteAfterGet = 1)
begin
    DELETE TOP 1 FROM Schedule WITH (READPAST) WHERE intScheduleType = @intScheduleType
    OUTPUT deleted.intUserID,deleted.intBlobID INTO @tblTempRow
end
else
begin
    INSERT INTO @tblTempRow(intUserID, intBlobID)
    SELECT TOP 1 intUserID, intBlobID FROM Schedule WHERE intScheduleType = @intScheduleType
end

-- Return the temp table.
SELECT intUserID, @intScheduleType, intBlobID FROM @tblTempRow