INSERT INTO [test] ([name],[subject],[Source]) values (N'张三',N'语文',60)
INSERT INTO [test] ([name],[subject],[Source]) values (N'李四',N'数学',70)
INSERT INTO [test] ([name],[subject],[Source]) values (N'王五',N'英语',80)
INSERT INTO [test] ([name],[subject],[Source]) values (N'王五',N'数学',75)
INSERT INTO [test] ([name],[subject],[Source]) values (N'王五',N'语文',57)
INSERT INTO [test] ([name],[subject],[Source]) values (N'李四',N'语文',80)
INSERT INTO [test] ([name],[subject],[Source]) values (N'张三',N'英语',100)
Go
交叉表语句的实现:
--用于:交叉表的列数是确定的
select name,sum(case subject when '数学' then source else 0 end) as '数学',
sum(case subject when '英语' then source else 0 end) as '英语',
sum(case subject when '语文' then source else 0 end) as '语文'
from test
group by name
--用于:交叉表的列数是不确定的
declare @sql varchar(8000)
set @sql = 'select name,'
select @sql = @sql + 'sum(case subject when '''+subject+'''
then source else 0 end) as '''+subject+''','
from (select distinct subject from test) as a
select @sql = left(@sql,len(@sql)-1) + ' from test group by name'
exec(@sql)
CREATE TABLE 表2 (学号 varchar(20),考试科目 VARCHAR(10),成绩 float)
--触发器
CREATE TRIGGER T_表2_IDU ON 表2
FOR INSERT,UPDATE,DELETE
AS
BEGIN
IF NOT EXISTS (SELECT 1 FROM DELETED)
BEGIN
IF EXISTS (SELECT 1 FROM INSERTED WHERE 考试科目='语文')
BEGIN
INSERT INTO 表1(学号,语文,数学)
SELECT 学号,成绩,NULL FROM INSERTED
END
IF EXISTS (SELECT 1 FROM INSERTED WHERE 考试科目='数学')
BEGIN
INSERT INTO 表1(学号,语文,数学)
SELECT 学号,NULL,成绩 FROM INSERTED
END
END
ELSE
BEGIN
IF NOT EXISTS (SELECT 1 FROM INSERTED)
BEGIN
DELETE A FROM 表1 A,DELETED B WHERE A.学号=B.学号
END
ELSE
BEGIN
IF EXISTS (SELECT 1 FROM INSERTED WHERE 考试科目='语文')
BEGIN
UPDATE A
SET 语文=B.考试科目
FROM 表1 A,INSERTED B WHERE A.学号=B.学号
END
IF EXISTS (SELECT 1 FROM INSERTED WHERE 考试科目='数学')
BEGIN
UPDATE A
SET 数学=B.考试科目
FROM 表1 A,INSERTED B WHERE A.学号=B.学号
END
END
END
END
--测试
INSERT INTO 表2
SELECT '10001','语文',90
INSERT INTO 表2
SELECT '10001','数学',80
--删除环境
DROP TABLE 表1,表2
--结果
/*
学号 语文 数学
------------ -----------------
10001 90.0 NULL
10001 NULL 80.0