Unity3D之高级查询

高级查询

模糊查询 ---like

定义：查询时，字段中的内容并不一定与查询内容完全匹配，只要字段中含有这些内容
select id,name from work where name like 'a'

模糊查询---between

定义：把某一字段中内容在特定范围内的记录查询出来
select id,name from work where id between 1 and 2

模糊查询---in

定义：把某一字段中内容与所列出的查询内容列表匹配的记录查询出来
select id,name from work where id in (1,2)

聚合函数

sum

select sum （id）as 总和 from work

avg

select avg (id) as 平均 from work

max

select max (id) as 最大 from work

min

select min (id) as 最大 from work

count

select count (id) as 最大 from work

分组查询:group by (平均id)

select avg (id) as 平均 from work group by id

多连接查询---分类

内联结：inner join
 
SELECT Students.SName, Score.CourseID, Score.Score
FROM     Students,Score
WHERE  Students.SCode = Score.StudentID

多表查询---三表联结

SELECT
S.SName AS 姓名, CS.CourseName AS 课程, C.Score AS 成绩
FROM Students AS S
INNER JOIN Score AS C ON (S.SCode = C.StudentID)
INNER JOIN Course AS CS ON (CS.CourseID = C.CourseID

多表联结查询---左外联结

SELECT S.SName,C.CourseID,C.Score

FROM   StudentsAS S

LEFT JOIN   ScoreAS C

ON   C.StudentID= S.SCode

多表联结查询---右外连接

SELECT Titles.Title_id, Titles.Title, Publishers.Pub_name
FROM titles
RIGHT OUTER JOIN Publishers
ON Titles.Pub_id = Publishers.Pub_id
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