SQL开发实例和优化是怎样的

这篇文章将为大家详细讲解有关SQL开发实例和优化是怎样的，文章内容质量较高，因此小编分享给大家做个参考，希望大家阅读完这篇文章后对相关知识有一定的了解。找出连续的数据 如1,2,3,48,50,51,52,53,67,68
找出连续的数字的起点和重点
1,3
48,48
51,53
67,68
create table test.range_problem(

a int not null,
primary key (a));
insert into test.range_problem values(1);

insert into test.range_problem values(2);
insert into test.range_problem values(3);
insert into test.range_problem values(48);
insert into test.range_problem values(50);
insert into test.range_problem values(51);
insert into test.range_problem values(52);
insert into test.range_problem values(53);
insert into test.range_problem values(66);
insert into test.range_problem values(67);

–思路1 找最后一个不连续的数
SELECT T1.A
FROM test.range_problem T1
WHERE NOT EXISTS
(
SELECT A
FROM test.range_problem T2
WHERE T2.A -1 = T1.A
)

–思路2 找所有行对应的结束值
SELECT ROW_NUMBER()OVER(ORDER BY TBASE.A) ID
,TBASE.A
,(SELECT Min(A)
FROM test.range_problem T1
WHERE NOT EXIST免费云主机域名S
(
SELECT A
FROM test.range_problem T2
WHERE T2.A -1 = T1.A
)
AND T1.A >= TBASE.A –T1.A 是3,48,53,67 TBASE.A 是每行的值
) A_END

FROM test.range_problem TBASE

–思路3 分组后找出所有连续的起始值和结束值
SELECT MIN(A) A_START, A_END
FROM(
SELECT ROW_NUMBER()OVER(ORDER BY TBASE.A) ID
,TBASE.A
,(SELECT Min(A)
FROM test.range_problem T1
WHERE NOT EXISTS
(
SELECT A
FROM test.range_problem T2
WHERE T2.A -1 = T1.A
)
AND T1.A >= TBASE.A –T1.A 是3,48,53,67 TBASE.A 是每行的值
) A_END

FROM test.range_problem TBASE
) T
GROUP BY T.A_END

–对上面语句的优化
WITH POT AS(
SELECT A
FROM test.range_problem T
WHERE NOT EXISTS
( SELECT A
FROM test.range_problem TC
WHERE TC.A -1 = T.A)
)

SELECT TBASE.A A_START,(SELECT MIN(A)
FROM POT T
WHERE TBASE.A ) A_END
FROM test.range_problem TBASE
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