最简单的查询语法格式:
SELECT <列名>
FROM <表名>
[WHERE <查询条件表达式>]
[ORDER BY <排序的列名> [ASC 或 DESC]]
·查询所有的数据行和列:
SELECT * FROM Student
·查询部分行列－－条件查询
SELECT SCode,SName,SAddress
FROM Student
WHERE SAddress = '陕西咸阳'()
★<>为不等于符号
SELECT SCode,SName,SAddress
FROM Student
WHERE SAddress <> '陕西咸阳'
★合并的新列名
SELECT FirstName+'.'+LastName AS '姓名'
FROM Employees
或
SELECT '姓名' = FirstName+'.'+LastName
FROM Employees
·查询空行
SELECT SName FROM Student WHERE SEmail IS NULL
·查询中使用常量列
★查询输出多了一列"学校名称"，该列的所有数据都是"陕西咸阳"
SELECT 姓名=SName,地址=SAddrees,'陕西咸阳' AS 学校名称
·查询贩货限制的行数
★TOP为限制行数的关键字
SELECT TOP 5 SName,SAddreess
FROM Student WHERE SSex=0
★百分比限制关键字PERCENT
SELECT TOP 20 PERCENT SName,SAddrees
FROM Student WHERE SSex = 0
·查询排序
★降低10%再加5，按照及格成绩排列
SELECT StudentID AD 学员编号，(Score*0.9+5) AS 综合成绩
FROM Score
WHERE (Score*0.9+5)>60
ORDER BY Score
★合并查到的所有姓名信息，然后按照姓名降序排列
SELECT Au_Lname + '.' + Au_Fname AS EMP FROM Author UNION
SELECT Fname + '.' + Lname AS EMP FROM Employee
ORDER BY EMP DESC
★多字段排序
SELECT StudentID AS 学员编号,Score AS 成绩
FROM Score
WHERE Score > 60
ORDER BY Score,CourseID(这两的字段有先后顺序)
·查询中使用函数
★更新信息,从表Card中把字段password中o改为0，i改为1
UPDATE Card SET password = REPLACE(密码,'o','0')
UPDATE Card SET password = REPLACE(密码,'i','1')
或
UPDATE Card SET password = REPLACE(REPLACE(密码,'o','0'),'i','1')
★特殊排序
排序前:13-1,13-2,13-3,13-10,13-100,13-108,13-18,13-11,13-15,14-1,14-2
排序后:13-1,13-2,13-3,13-10,13-11,13-15,13-18,13-100,13-108,14-1,14-2
SELCT ListNumber
FROM SellRecord
ORDER BY Convert(int,Left(ListNumber,Charindex('-',ListNumber)-1)),
Convert(int,Stuff(ListNumber,1,Charindex('-',ListNumber),''))
·模糊查询
★使用LIKE进行模糊查询
SELECT * FROM Student WHERE SName LIKE '王%'
★使用BETWEEN在某个范围内进行查询
SELECT * FROM SCore WHERE Score BETWEEN 60 AND 80
★查询不在1992年8月1号到1993年8月1号之间订购的读书列表
SELELCT * FROM Sales WHERE ord_date NOT BETWEEN '1992-8-1' AND '1993-8-1'
★使用IN在列举值内进行查询
SELECT SName AS 学员姓名 FROM Student WHERE SAddress IN ('北京','广州','上海')
ORDER BY SAddress
·SQL Server 中的聚合函数
★SUM(只能返回一个数值)
SELECT SUM(ytd_sales) FROM tiles WHERE tyde = 'business'
★AVG
SELECT AVG(SCore) AS 平均成绩 FROM Score WHERE Score >=60
★MAX、MIN
SELECT AVG(Score) AS 平均成绩,MAX(Score) AS 最高分,MIN(Score) AS 最低分
FROM Score WHERE Score >=60
★COUNT(返回提供的表达式中非空值的计数，可以用数字和字符类型的列)
SELELCT COUNT(*) AS 及格人数 FROM Score WHERE Score >=60
·分组查询
★使用GROUP BY进行分组查询
SELECT CourseID,AVG(Score) AS 课程平均成绩
FROM Score
GROUP BY CourseID
·多表连接查询
★内连接
SELECT Student,SName,Score.CourseID,Score.Score
FROM Student,Score
WHERE Student.Score = Score.StudentID
或
SELECT S.SName,C.CourseID,C.Score
FROM Student AS S INNER JOIN Score AS C
ON (S.Score=C.StudentID)
★三表连接查询
SELECT S.SName AS 学员姓名,CS.CourseName AS 课程名称,C.Score AS 考试成绩
FROM Student AS S
INNER JOIN Score AS C ON (S.Score=C.StudentID)
INNER JOIN Course AS CS ON (CS.CourseID=C.CourseID)
★左外连接查询
SELECT S.SName,C.CourseID,C.Score
FROM Student AS S
LEFT OUTER JOIN Score AS C ON S.Score = C.StudentID
★右外连接查询
SELECT Titles.Title_id,Titles.Title,Publishers.Pub_name
FROM titles
RIGHT OUTER JOIN Publishers ON Titles.Pub_id = Publishers.Pub_id
·案例分析
★★查询一张表中的奇数和偶数行
1、只能依靠标识列的值来进行判断和选取
2、数据行可能存在增加，修改和删除，因此标识列的数据值并不完全可靠
3、SELECT
INTO创建一张新表，顺便创建新的表示列，再在新的表示列上执行奇偶判断
4、奇数的判断依据为：标识列值%2不等与0；偶数的判断依据为：标识列值%2等于0
5、删除临时表TEMPTABLE
SELECT A,TDENTITY(INT 1,1) AS ID
INTO TEMPTABLE
FROM TBL
SELECT SUM(A) AS 奇数列汇总 FROM TEMPTABLE
WHERE ID%2 <> 0
SELECT SUM(A) AS 偶数列汇总 FROM TEMPTABLE
WHERE ID%2 = 0posted on 2007-12-01 11:02
凌晨风 阅读(880)
评论(0) 编辑 收藏 所属分类:
Java学习笔记