SQL

--创建范例学生表
CREATE TABLE Student
(
    StuId UNIQUEIDENTIFIER,
    StuName VARCHAR(10),
    Age INT,
    Phone VARCHAR(20)
)
GO

--新增(主键是随机数)
INSERT INTO Student(StuId,StuName,Age,Phone)VALUES(NEWID(),'yhz',25,'150xxxxxxxxxxx') 

--删除一列(删除UNIQUEIDENTIFIER类型的列)
ALTER TABLE student DROP COLUMN StuId

--新增一列(新增varchar类型的StuId列)
ALTER TABLE  Student ADD Stuid VARCHAR(20)

--修改表的数据类型(将StuId列的数据类型改为int)
ALTER TABLE student ALTER COLUMN Stuid INT NOT NULL


--添加主键约束
ALTER TABLE student ADD CONSTRAINT primarykey PRIMARY KEY(stuid)


---随机抽奖 砸金蛋游戏

SELECT *
FROM GameAward A
WHERE Amount > 0
AND GameInteractionID = 558
AND 3 > ISNULL(
(
SELECT SUM(Amount)
FROM GameAward
WHERE A.GameInteractionID = GameInteractionID
AND GameAwardID < A.GameAwardID
),
0
)
AND 3 <= ISNULL(
(
SELECT SUM(Amount)
FROM GameAward
WHERE A.GameInteractionID = GameInteractionID
AND GameAwardID <= A.GameAwardID
),
0
)