SELECT * FROM result

--去重 DISTINCT
SELECT `studentno` FROM result
--DISTINCT  去重，去除SELECT查詢出來的重複的資料
SELECT DISTINCT `studentno` FROM result

SELECT VERSION()  --查詢系統版本
SELECT 100*2-1 AS 結果  --用來計算
SELECT @@auto_increment_increment  --查詢自增的步長(變數)
--學員考試成績全部加一
SELECT `studentno`,`studentresult`+1 AS 提分後 FROM
 
 result

--=====================  WHERE ========================
--查詢考試成績在90到95之間的學生的學號和成績
SELECT `studentno`,`studentresult` FROM result 
    WHERE studentresult>=95 AND studentresult<=100
    
SELECT `studentno`,`studentresult` FROM result 
    WHERE studentresult BETWEEN 95 AND 100 

--查詢除了1000號的學生的成績
 

SELECT `studentno`,`studentresult` FROM result
    WHERE studentno!=1000 AND studentno!=1001
    
SELECT `studentno`,`studentresult` FROM result
    WHERE NOT studentno=1000

--=====================  模糊查詢 ========================
--查詢名字以夜開頭的     %(任意字元)   _(一個字元)  與LIKE匹配使用
SELECT `studentno`,`studentname` FROM
 
 `student`
    WHERE `studentname` LIKE '夜%' 
    
SELECT `studentno`,`studentname` FROM `student`
    WHERE `studentname` LIKE '張_'
    
SELECT `studentno`,`studentname` FROM `student`
    WHERE `studentname` LIKE '%雨%'
    
--===============IN 具體的一個或多個值==================
SELECT `studentno`,`studentname` FROM `student`
    WHERE `studentno` IN (1000,1001,1002)
    
--查詢地址為空的學生  IS NULL     IS NOT NULL 
SELECT `studentno`,`studentname` FROM `student`
    WHERE address='' OR address IS NULL