MySQL高級(jí)SQL語(yǔ)句

use kgc;create table location (Region char(20),store_name char(20));insert into location values (’East’,’Boston’) ;insert into location values (’East’,’New York’);insert into location values (’west’,’Los Angeles’);insert into location values (’west’,’Houston’) ;

create table Store_Info (Store_Name char(20),sales int(10),Date char(10));insert into Store_Info values (’Los Angeles’,’1500’,’2020-12-05’);insert into Store_Info values (’Houston’,’250’,’2020-12-07’);insert into Store_Info values (’Los Angeles’,’300’,’2020-12-08’);insert into Store_Info values (’Boston’,’700’,’2020-12-08’);

SELECT

---- SELECT ---- 顯示表格中一個(gè)或數(shù)個(gè)欄位的所有資料語(yǔ)法: SELECT '欄位' FROM '表名';SELECT Store_Name FROM Store_Info;

DISTINCT

---- DISTINCT ---- 不顯示重復(fù)的資料語(yǔ)法: SELECT DISTINCT '欄位' FROM '表名';SELECT DISTINCT Store_Name FROM Store_Info;

WHERE

---- WHERE ---- 有條件查詢語(yǔ)法:SELECT '欄位” FROM '表名' WHERE '條件';SELECT Store_Name FROM Store_Info WHERE Sales > 1000;

AND OR

---- AND OR ---- 且 或語(yǔ)法:SELECT '欄位' FROM '表名” WHERE '條件1' {[ANDIOR] '條件2'}+;SELECT Store_Name FROM Store_Info WHERE Sales > 1000 OR (Sales < 500 AND Sales > 200);

IN

---- IN ---- 顯示己知的值的資料語(yǔ)法: SELECT '欄位' FROM '表名' WHERE '欄位' IN (’值1’,’值2’, ...);SELECT * FROM Store_Info WHERE Store_Name IN (’Los Angeles’,’Houston’);

BETWEEN

---- BETWEEN ---- 顯示兩個(gè)值范圍內(nèi)的資料語(yǔ)法:SELECT '欄位' FROM '表名' WHERE '欄位' BETWEEN ’值1’ AND ’值2’;SELECT * FROM Store_Info WHERE Date BETWEEN ’2020-12-06’ AND ’2020-12-10’;

通配符

---- 通配符 ---- 通常通配符都是跟LIKE一起使用的% : 百分號(hào)表示零個(gè)、一個(gè)或多個(gè)字符_ : 下劃線表示單個(gè)字符’A_Z’:所有以‘A’起頭，另一個(gè)任何值的字符，且以Z’為結(jié)尾的字符串。例如，’A.BZ’和‘A.22’都符合這一個(gè)模式，而‘AKK2’并不符合(因?yàn)樵贏和Z之間有兩個(gè)字符，而不是一個(gè)字符)。’ABC%’:所有以’ABC’起頭的字符串。例如，’ABCD’和’ABCABC’都符合這個(gè)模式。’%XYZ’:所有以’XYZ’結(jié)尾的字符串。例如，’WXYZ’和‘ZZXYZ’都符合這個(gè)模式。’%AN%’:所有含有’AN’這個(gè)模式的字符串。例如，’LOS ANGELES’和’SAN FRANCISCO’都符合這個(gè)模式。’_AN%’:所有第二個(gè)字母為‘A’和第三個(gè)字母為’N’的字符串。例如，’SAMN FRANCITSCO’符合這個(gè)模式，而’LOS ANGELES’則不符合這個(gè)模式。---- LIKE ---- 匹配一個(gè)模式來(lái)找出我們要的資料語(yǔ)法:SELECT '欄位' FROM '表名' WHERE '欄位' LIKE {模式};SELECT * FROM Store_Info WHERE Store_Name like ’%os%’;---- ORDER BY ---- 按關(guān)鍵字排序語(yǔ)法:SELECT '欄位' FROM '表名' [WHERE '條件'] ORDER BY '欄位' [ASC，DESC];#ASC是按照升序進(jìn)行排序的,是默認(rèn)的排序方式。#DESC是按降序方式進(jìn)行排序。SELECT Store_Name,Sales,Date FROM Store_Info ORDER BY Sales DESC;

函數(shù) 數(shù)學(xué)函數(shù)

abs(x)#返回x的絕對(duì)值rand()#返回0到1的隨機(jī)數(shù)mod(x,y) #返回x除以y以后的余數(shù)power(x,y) #返回x的y次方round(x) #返回離x最近的整數(shù)round(x,y) #保留x的y位小數(shù)四舍五入后的值sqrt(x) #返回x的平方根truncate(x,y) #返回?cái)?shù)字x截?cái)酁閥位小數(shù)的值ceil(×) #返回大于或等于x的最小整數(shù)floor(x) #返回小于或等于x的最大整數(shù)greatest(x1,x2...) #返回集合中最大的值least(x1,x2...) #返回集合中最小的值SELECT abs(-1),rand(),mod(5,3),power(2,3),round(1.89);SELECT round(1.8937,3),truncate(1.235,2),ceil(5.2),floor(2.1),least(1.89,3,6.1,2.1);

聚合函數(shù)

聚合函數(shù):avg() #返回指定列的平均值count() #返回指定列中非 NULL值的個(gè)數(shù)min() #返回指定列的最小值max() #返回指定列的最大值sum(x) #返回指定列的所有值之和SELECT avg(Sales) FROM Store_Info;SELECT count(store_Name) FROM Store_Info;SELECT count(DISTINCT store_Name) FROM Store_Info;SELECT max(Sales) FROM Store_Info;SELECT min(sales) FROM Store_Info;SELECT sum(sales) FROM Store_Info;SELECT count(DISTINCT store_Name) FROM Store_Info;SELECT count(*) FROM Store_Info;#count(*)包括了所有的列的行數(shù)，在統(tǒng)計(jì)結(jié)果的時(shí)候，不會(huì)忽略列值為NULL#count(列名)只包括列名那一列的行數(shù)，在統(tǒng)計(jì)結(jié)果的時(shí)候，會(huì)忽略列值為NULL的行

字符串函數(shù)

字符串函數(shù):trim() #返回去除指定格式的值concat(x,y)#將提供的參數(shù)x和y拼接成一個(gè)字符串substr(x,y)#獲取從字符串x中的第y個(gè)位置開(kāi)始的字符串，跟substring()函數(shù)作用相同substr(x,y,z) #獲取從字符串x中的第y個(gè)位置開(kāi)始長(zhǎng)度為z的字符串length(x) #返回字符串x的長(zhǎng)度replace(x,y,z) #將字符串z替代字符串x中的字符串yupper(x) #將字符串x的所有字母變成大寫(xiě)字母lower(x) #將字符串x的所有字母變成小寫(xiě)字母left(x,y) #返回字符串x的前y個(gè)字符right(x,y) #返回字符串x的后y個(gè)字符repeat(x,y)#將字符串x重復(fù)y次space(x) #返回x個(gè)空格strcmp (x,y) #比較x和y，返回的值可以為-1,0,1reverse(x) #將字符串x反轉(zhuǎn)SELECT concat(Region,Store_Name) FROM location WHERE Store_Name = ’Boston’;#如sql_mode開(kāi)啟開(kāi)啟了PIPES_AS_CONCAT，'||'視為字符串的連接操作符而非或運(yùn)算符,和字符串的拼接函數(shù)concat相類似，這和Oracle數(shù)據(jù)庫(kù)使用方法一樣的SELECT Region || ’ ’ || Store_Name FROM location WHERE Store_Name = ’Boston’;SELECT substr(Store_Name,3) FROM location WHERE Store_Name = ’Los Angeles’;SELECT substr(Store_Name,2,4) FROM location WHERE Store_Name = ’New York’;SELECT TRIM ([ [位置] [要移除的字符串] FROM ] 字符串);#[位置]:的值可以為 LEADING(起頭)，TRAILING(結(jié)尾)，BOTH(起頭及結(jié)尾)。#[要移除的字符串]:從字串的起頭、結(jié)尾，或起頭及結(jié)尾移除的字符串。缺省時(shí)為空格SELECT TRIM(LEADING ’Ne’ FROM ’New York’);SELECT Region,length(Store_Name) FROM location;SELECT REPLACE(Region,’ast’,’astern’)FROM location;

---- GROUP BY ---- 對(duì)GROUP BY后面的欄位的查詢結(jié)果進(jìn)行匯總分組，通常是結(jié)合聚合函數(shù)一起使用的GROUP BY有一個(gè)原則，就是SELECT后面的所有列中，沒(méi)有使用聚合函數(shù)的列，必須出現(xiàn)在GROUP BY后面。語(yǔ)法:SELECT '欄位1',SUM('欄位2') FROM '表名' GROUP BY '欄位1';SELECT Store_Name,SUM(Sales) FROM Store_Info GROUP BY Store_Name ORDER BY sales desc;---- HAVING ---- 用來(lái)過(guò)濾由GROUP BY語(yǔ)句返回的記錄集，通常與GROUP BY語(yǔ)句聯(lián)合使用HAVING語(yǔ)句的存在彌補(bǔ)了wHERE關(guān)鍵字不能與聚合函數(shù)聯(lián)合使用的不足。如果被SELECcT的只有函數(shù)欄，那就不需要GROUP BY子句。語(yǔ)法:SELECT '欄位1',SUM('欄位2') FROM '表格名' GROUP BY '欄位1' HAVING (函數(shù)條件);SELECT Store_Name,SUM(Sales) FROM Store_Info GROUP BY Store_Name HAVING SUM (Sales) > 1500;---- 別名 ---- 欄位別名表格別名語(yǔ)法:SELECT '表格別名'.'欄位1” [AS] '欄位別名' FROM '表格名' [AS] '表格別名'SELECT A.Store_Name Store，SUM(A.Sales) 'Total Sales' FROM Store_Info A GROUP BY A.Store_Name;---- 子查詢 ---- 連接表格，在WHERE子句或 HAVING子句中插入另一個(gè) SQL語(yǔ)句語(yǔ)法: SELECT '欄位1' FROM '表格1' WHERE '欄位2' [比較運(yùn)算符] #外查詢(SELECT '欄位1' FROM '表格2' WHERE '條件'); #內(nèi)查詢可以是符號(hào)的運(yùn)算符，例如 =、>、<、>=、<= ;也可以是文字的運(yùn)算符，例如LIKE、IN、BETWEENSELECT SUM(Sales) FROM Store_Info WHERE Store_Name IN(SELECT Store_Name FROM location WHERE Region = ’west’);SELECT SUM(A.Sales) FROM Store_Info A WHERE A.Store_Name IN(SELECT Store_Name FROM location B WHERE B.Store_Name = A.Store_Name);

EXISTS

---- EXISTS ---- 用來(lái)測(cè)試內(nèi)查詢有沒(méi)有產(chǎn)生任何結(jié)果，類似布爾值是否為真#如果有的話，系統(tǒng)就會(huì)執(zhí)行外查詢中的SQL語(yǔ)句。若是沒(méi)有的話，那整個(gè)SQL語(yǔ)句就不會(huì)產(chǎn)生任何結(jié)果。語(yǔ)法: SELECT '欄位1' FROM '表格1' WHERE EXISTS (SELECT * FROM '表格2' WHERE '條件');SELECT SUM(Sales) FROM Store_Info WHERE EXISTS (SELECT * FROM location WHERE Region = ’West’);

連接查詢

location 表格

UPDATE Store_Info SET store_name=’washington’WHERE sales=300;

Store_Info表格

inner join(內(nèi)連接):只返回兩個(gè)表中聯(lián)結(jié)字段相等的行l(wèi)eft join(左連接):返回包括左表中的所有記錄和右表中聯(lián)結(jié)字段相等的記錄right join(右連接):返回包括右表中的所有記錄和左表中聯(lián)結(jié)字段相等的記錄SELECT * FROM location A INNER JOIN Store_Info B on A.Store_Name = B.store_Name ;SELECT * FROM location A RIGHT JOIN Store_Info B on A.Store_Name = B.Store_Name ;SELECT * FROM location A,store_Info B WHERE A.Store_Name = B.Store_Name;SELECT A.Region REGION,SUM(B.Sales) SALES FROM location A,Store_Info BWHERE A.Store_Name = B.Store_Name GROUP BY REGION;

CREATE VIEW

---- CREATE VIEW ---- 視圖，可以被當(dāng)作是虛擬表或存儲(chǔ)查詢。·視圖跟表格的不同是，表格中有實(shí)際儲(chǔ)存資料，而視圖是建立在表格之上的一個(gè)架構(gòu)，它本身并不實(shí)際儲(chǔ)存資料。·臨時(shí)表在用戶退出或同數(shù)據(jù)庫(kù)的連接斷開(kāi)后就自動(dòng)消失了，而視圖不會(huì)消失。·視圖不含有數(shù)據(jù)，只存儲(chǔ)它的定義，它的用途一般可以簡(jiǎn)化復(fù)雜的查詢。比如你要對(duì)幾個(gè)表進(jìn)行連接查詢，而且還要進(jìn)行統(tǒng)計(jì)排序等操作，寫(xiě)SQT語(yǔ)句會(huì)很麻煩的，用視圖將幾個(gè)表聯(lián)結(jié)起來(lái)，然后對(duì)這個(gè)視圖進(jìn)行查詢操作，就和對(duì)一個(gè)表查詢一樣，很方便。語(yǔ)法:CREATE VIEW '視圖表名” AS 'SELECT語(yǔ)句';CREATE VIEW V_REGION_SALES AS SELECT A.Region REGION, SUM(B.Sales) SALES FROM location AINNER JOIN Store_Info B ON A.Store_Name = B.Store_Name GROUP BY REGION;SELECT * FROM V_REGION_SALES;DROP VIEW V_REGION_SALES;

UNION

---- UNION ---- 聯(lián)集，將兩個(gè)SQL語(yǔ)句的結(jié)果合并起來(lái)，兩個(gè)SQI語(yǔ)句所產(chǎn)生的欄位需要是同樣的資料種類UNION:生成結(jié)果的資料值將沒(méi)有重復(fù)，且按照字段的順序進(jìn)行排序語(yǔ)法:[SELECT 語(yǔ)句 1] UNION [SELECT 語(yǔ)句2];UNION ALL:將生成結(jié)果的資料值都列出來(lái)，無(wú)論有無(wú)重復(fù)語(yǔ)法:[SELECT 語(yǔ)句 1] UNION ALL [SELECT 語(yǔ)句 2];SELECT Store_Name FROM location UNION SELECT Store_Name FROM Store_Info;SELECT Store_Name FROM location UNION ALL SELECT Store_Name FROM Store_Info;

交集值

----- 交集值 ---- 取兩個(gè)SQL語(yǔ)句結(jié)果的交集SELECT A.Store_Name FROM location A INNER JOIN Store_Info B ON A.Store_Name = B.Store_Name;SELECT A.Store_Name FROM location A INNER JOIN Store_Info B USING(Store_Name);#兩表基中的一個(gè)表沒(méi)有指定的行，而另一個(gè)表這個(gè)行有重復(fù)，并且確實(shí)有交集的時(shí)候用SELECT A.Store_Name FROM(SELECT Store_Name FROM location UNION ALL SELECT Store_Name FROM store_Info) AGROUP BY A.Store_Name HAVING COUNT(*) > 1;#取兩個(gè)sQL語(yǔ)句結(jié)果的交集,且沒(méi)有重復(fù)SELECT A.Store_Name FRONM (SELECT B.Store_Name FROM location B INNER JOIN Store_Info C ON B.Store_Name = C.store_Name) AGROUP BY A.Store_Name;SELECT DISTINCT A.Store_Name FROM location A INNER JOIN Store_Info B USING(Store_Name);SELECT DISTIMCT Store_Name FROM location WHERE (Store_Name) IN (SELECT Store_Name FROM Store_Info);SELECT DISTINCT A.Store_Name FROM location A LEFT JOIN Store_Info B USING(Store_Name) WHERE B.Store_Name IS NOT NULL;

無(wú)交集值

---- 無(wú)交集值 ---- 顯示第一個(gè)sQL語(yǔ)句的結(jié)果，且與第二個(gè)SQL語(yǔ)句沒(méi)有交集的結(jié)果，且沒(méi)有重復(fù)SELECT DISTINCT Store_Name FROM location WHERE (Store_Name) NOT IN (SELECT Store_Name FROM Store_Info);SELECT DISTINCT A.Store_Name FROM location A LEFT JOIN Store_Info B USING(Store_Name) WHERE B.Store_Name IS NULL;

CASE

---- CASE ---- 是 SQL 用來(lái)做為 IF-THEN-ELSE 之類邏輯的關(guān)鍵字語(yǔ)法:SELECT CASE ('欄位名') WHEN '條件1” THEN '結(jié)果1' WHEN '條件2' THEN '結(jié)果2' ... [ELSE '結(jié)果N'] ENDFROM '表名';#'條件'可以是一個(gè)數(shù)值或是公式。ELSE子句則并不是必須的。SELECT store_Name, CASE Store_Name WHEN ’Los Angeles’ THEN Sales * 2 WHEN ’Boston’ THEN Sales * 1.5 ELSE Sales END'New Sales',DateFROM Store_Info;#'New Sales'是用于CASE 那個(gè)欄位的欄位名。CREATE TABLE Total_Sales (Name char(10),sales int(5));INSERT INTO Total_Sales VALUES (’zhangsan’,10);INSERT INTO Total_Sales VALUES (’lisi’,15);INSERT INTO Total_Sales VALUES (’wangwu’,20);INSERT INTO Total_Sales VALUES (’zhaoliu’,40);INSERT INTO Total_Sales VALUES (’sunqi’,50);INSERT INTO Total_Sales VALUES (’zhouba’,20);INSERT INTO Total_Sales VALUES (’wujiu’,30);

1、算排名

----算排名----表格自我連結(jié)(Self Join)，然后將結(jié)果依序列出，算出每一行之前〈包含那一行本身)有多少行數(shù)SELECT A1.Name, A1.sales,COUNT(A2.sales) Rank FROM Total_sales A1,Total_sales A2WHERE A1.sales < A2.sales 0R (A1.sales = A2.sales AND A1.Name = A2.Name)GROUP BY A1.Name, A1.sales ORDER BY A1.sales DESC;例如：select A1.Name,A1.sales,count(A2.sales) rank from Total_Sales A1,Total_Sales A2 where A1.sales < A2.sales OR (A1.sales=A2.sales and A1.Name=A2.Name) group by A1.Name order by A1.sales desc;解釋：當(dāng)A1的sales字段值小于A2的sales字段值、或者兩表sales字段值相等并且Name字段值相等時(shí)，從A1和A2表中查詢A1的Name字段值、A1的sales字段值、和A2的sales字段的非空值rank是別名，并為A1的Name字段分組，A1的sales字段降序排序

2、算中位數(shù)

---- 算中位數(shù) ----SELECT Sales Middle FROM (SELECT A1.Name,A1.Sales,COUNT(A2.Sales) Rank FROM Total_Sales A1,Total_Sales A2WHERE A1.Sales < A2.Sales 0R (A1.Sales = A2.Sales AND A1.Name >= A2.Name)GROUP BY A1.Name,A1.Sales ORDER BY A1.Sales DESC) A3WHERE A3.Rank = (SELECT (COUNT(*)+1) DIV 2 FROM Total_Sales);例如：select * from (select A1.Name,A1.sales,count(A2.sales) rank from Total_Sales A1,Total_Sales A2 where A1.sales < A2.sales OR (A1.sales=A2.sales and A1.Name=A2.Name) group by A1.Name order by A1.sales desc) A3 where A3.rank = (select (count(*)+1) DIV 2 from Total_Sales);select sales mid from (select A1.Name,A1.sales,count(A2.sales) rank from Total_Sales A1,Total_Sales A2 where A1.sales < A2.sales OR (A1.sales=A2.sales and A1.Name=A2.Name) group by A1.Name order by A1.sales desc) A3 where A3.rank = (select (count(*)+1) DIV 2 from Total_Sales);#每個(gè)派生表必須有自己的別名，所以別名A3必須要有#DIV 是在MySQL中算出商的方式

3、算累積總計(jì)

---- 算累積總計(jì) ---- 表格自我連結(jié)(Self Join)，然后將結(jié)果依序列出,算出每一行之前(包含那一行本身)的總合SELECT A1.Name, A1.Sales, SUM(A2.Sales) Sum_Total FROM Total_Sales A1，Total_Sales A2WHERE A1.Sales < A2.Sales OR (A1.Sales=A2.Sales AND A1.Name = A2.Name)GROUP BY A1.Name,A1.Sales ORDER BY A1.Sales DESC;例如：select A1.*,sum(A2.sales) sum_soales from Total_Sales A1,Total_Sales A2 where A1.sales < A2.sales or(A1.sales=A2.sales and A1.Name=A2.Name) group by A1.Name order by A1.sales desc;

4、算總合百分比

例如：select A1.*,A1.sales/(select sum(sales) from Total_Sales) z_sum from Total_Sales A1,Total_Sales A2 where A1.sales < A2.sales or (A1.sales=A2.sales and A1.Name=A2.Name) group by A1.Name;#select sum(sales) from Total_Sales 是為了算出字段值總合，然后每一行一一除以總合，算出每行的總合百分比。

5、算累計(jì)總合百分比

例如：select A1.Name,A1.sales,sum(A2.sales),sum(A2.sales)/(select sum(sales) from Total_Sales) Z from Total_Sales A1,Total_Sales A2 where A1.sales < A2.sales or (A1.sales=A2.sales and A1.Name=A2.Name) group by A1.Name order by A1.sales desc;select A1.Name,A1.sales,sum(A2.sales),TRUNCATE(sum(A2.sales)/(select sum(sales) from Total_Sales),2) ||’%’ Z from Total_Sales A1,Total_Sales A2 where A1.sales < A2.sales or (A1.sales=A2.sales and A1.Name=A2.Name) group by A1.Name order by A1.sales desc;

6、空值（null）和無(wú)值（’ ’）的區(qū)別

1、無(wú)值的長(zhǎng)度為0，不占用空間；而空值null 的長(zhǎng)度是null，是占用空間的2、IS NULL或者IS NOT NULL，是用來(lái)判斷字段是不是NULL或者不是NULL，是不能查出是不是無(wú)值的3、無(wú)值的判斷使用=’‘或者<>’’來(lái)處理。<>代表不等于4、在通過(guò)count()指定字段統(tǒng)計(jì)又多少行數(shù)時(shí)，如果遇到NULL值會(huì)自動(dòng)忽略掉，遇到空值會(huì)自動(dòng)加入記錄中進(jìn)行計(jì)算

例如：create table SITE(site varchar(20));insert into SITE values(’nanjing’);insert into SITE values(’beijing’);insert into SITE values(’’);insert into SITE values(’taijin’);insert into SITE values();insert into SITE values(’’);select * from SITE;

select length(site) from SITE;select * from SITE where site is NULL;select * from SITE where site is not NULL;select * from SITE where site =’’;select * from SITE where site <> ’’;

7、正則表達(dá)式(與Shell部分一樣)

匹配模式描述實(shí)例^ 匹配文本的開(kāi)始字符 ‘^bd’ 匹配以 bd 開(kāi)頭的字符串$ 匹配文本的結(jié)束字符 ‘qn$’ 匹配以 qn 結(jié)尾的字符串. 匹配任何單個(gè)字符‘s.t’ 匹配任何 s 和 t 之間有一個(gè)字符的字符串* 匹配零個(gè)或多個(gè)在它前面的字符 ‘fo*t’ 匹配 t 前面有任意個(gè) o+ 匹配前面的字符 1 次或多次‘hom+’ 匹配以 ho 開(kāi)頭，后面至少一個(gè)m 的字符串字符串 匹配包含指定的字符串 ‘clo’ 匹配含有 clo 的字符串p1|p2 匹配 p1 或 p2 ‘bg|fg’ 匹配 bg 或者 fg[...] 匹配字符集合中的任意一個(gè)字符 ‘[abc]’ 匹配 a 或者 b 或者 c[^...] 匹配不在括號(hào)中的任何字符 ‘[^ab]’ 匹配不包含 a 或者 b 的字符串{n} 匹配前面的字符串 n 次 ‘g{2}’ 匹配含有 2 個(gè) g 的字符串{n,m}匹配前面的字符串至少 n 次，至多m 次‘f{1,3}’ 匹配 f 最少 1 次，最多 3 次

語(yǔ)法：SELECT 字段 FROM 表名 WHERE 字段 REGEXP 匹配模式

例如：select * from Total_Sales where Name regexp ’^[n]’;select * from Total_Sales where Name regexp ’[n]’;select * from Total_Sales where Name regexp ’Ho|Bo’;

8、存儲(chǔ)過(guò)程（與Shell函數(shù)差不多,代碼的復(fù)用） 存儲(chǔ)過(guò)程是一組為了完成特定功能的SQL語(yǔ)句集合

存儲(chǔ)過(guò)程在使用過(guò)程中是將常用或者復(fù)雜的工作預(yù)先使用SQL語(yǔ)句寫(xiě)好并用一個(gè)指定的名稱來(lái)進(jìn)行儲(chǔ)存，這個(gè)過(guò)程經(jīng)編譯和優(yōu)化后存儲(chǔ)在數(shù)據(jù)庫(kù)服務(wù)器中，當(dāng)需要使用該存儲(chǔ)過(guò)程時(shí)，只需要調(diào)用它即可，存儲(chǔ)過(guò)程在執(zhí)行上比傳統(tǒng)SQL速度更快，執(zhí)行效率更高。 存儲(chǔ)過(guò)程的優(yōu)點(diǎn)1、執(zhí)行一次后，會(huì)將生成的二進(jìn)制代碼駐留緩沖區(qū)，提高執(zhí)行效率2、SQL語(yǔ)句加上控制語(yǔ)句的集合，靈活性高3、在服務(wù)器端存儲(chǔ)，客戶端調(diào)用時(shí)，降低網(wǎng)絡(luò)負(fù)載4、可多次重復(fù)被調(diào)用，可隨時(shí)修改，不影響客戶端調(diào)用5、可完成所有的數(shù)據(jù)庫(kù)操作，也可控制數(shù)據(jù)庫(kù)的信息訪問(wèn)權(quán)限

語(yǔ)法：DELIMITER !! #將語(yǔ)句的結(jié)束符號(hào)從分號(hào)；臨時(shí)修改，以防出問(wèn)題，可以自定義CREATE PROCEDURE XXX() #創(chuàng)建存儲(chǔ)過(guò)程，過(guò)程名自定義,（）可帶參數(shù) BEGIN #過(guò)程體以關(guān)鍵字BEGIN開(kāi)始 select * from xxx; #過(guò)程體語(yǔ)句 END!! #過(guò)程體以關(guān)鍵字END結(jié)尾DELIMITER ; #將語(yǔ)句的結(jié)束符號(hào)恢復(fù)為分號(hào)call XXX; #調(diào)用存儲(chǔ)過(guò)程====查看存儲(chǔ)過(guò)程====show create procedure [數(shù)據(jù)庫(kù).]儲(chǔ)存過(guò)程名; #查看某個(gè)儲(chǔ)存過(guò)程的具體信息show create procedure XXX;show procedure status [like ’%XXX%’] G

例如：DELIMITER !!CREATE PROCEDURE KIND1()BEGINselect * from Total_Sales;END!!DELIMITER ;CALL KIND1;show create procedure KIND1Gshow procedure status like ’%KIND1%’G

存儲(chǔ)過(guò)程的參數(shù)：IN 輸入?yún)?shù)，表示調(diào)用者向過(guò)程傳入值（傳入值可以是字面量或變量）OUT 輸出參數(shù)：表示過(guò)程向調(diào)用者傳出值（可以返回多個(gè)值，傳出值只能是變量）

例如：DELIMITER !!CREATE PROCEDURE KIND2(IN people char(20))BEGINselect * from Total_Sales where Name=people;END!! DELIMITER ;CALL KIND2(’lisi’);

8.1、存儲(chǔ)過(guò)程的條件語(yǔ)句

例如：DELIMITER !!CREATE PROCEDURE KIND7(IN num int(10))BEGINdeclare var int;set var=num*2;if var>=10 thenupdate Total_Sales set sales=sales+1;else update Total_Sales set sales=sales-1;end if;END!!DELIMITER ;CALL KIND7(5);CALL KIND7(4);

8.2、循環(huán)語(yǔ)句while

例如：create table akg(id int);DELIMITER !!CREATE PROCEDURE KIND6()BEGINdeclare var int;set var=0;while var<5 doinsert into akg values(var);set var=var+1;end while;END!!DELIMITER ;CALL KIND6;select * from akg;

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