1添
1.1【插入單行】
insert [into] (列名) values (列值)
例:insert into Strdents (姓名,性別,出生日期) values ('開心朋朋','男','1980/6/15')
1.2【將現有表數據添加到一個已有表】
insert into (列名) select from
例:insert into tongxunlu ('姓名','地址','電子郵件')
select name,address,email
from Strdents
1.3【直接拿現有表數據創建一個新表并填充】
select into from
例:select name,address,email into tongxunlu from strdents
1.4【使用union關鍵字合并數據進行插入多行】
insert select tnion select
例:insert Students (姓名,性別,出生日期)
select '開心朋朋','男','1980/6/15'?union(union表示下一行)
select '藍色小明','男','19**/**/**'
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
2刪
2.1【刪除行】
delete from [where ]
例:delete from a where name='開心朋朋'(刪除表a中列值為開心朋朋的行)
2.2【刪除整個表】
truncate table
truncate table tongxunlu
注意:刪除表的所有行,但表的結構、列、約束、索引等不會被刪除;不能用語有外建約束引用的表
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
3改
update set [where ]
例:update tongxunlu set 年齡=18 where 姓名='藍色小名'
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
4.查
4.1`精確(條件)查詢
select from [where ] [order by [asc或desc]]
4.1.1【查詢所有數據行和列】
例:select * from a
說明:查詢a表中所有行和列
4.1.2【查詢部分行列--條件查詢】
例:select i,j,k from a where f=5
說明:查詢表a中f=5的所有行,并顯示i,j,k3列
4.1.3【在查詢中使用AS更改列名】
例:select name as 姓名 from a where xingbie='男'
說明:查詢a表中性別為男的所有行,顯示name列,并將name列改名為(姓名)顯示
4.1.4【查詢空行】
例:select name from a where email is null
說明:查詢表a中email為空的所有行,并顯示name列;SQL語句中用is null或者is not null來判斷是否為空行
4.1.5【在查詢中使用常量】
例:select name, '唐山' as 地址 from Student
說明:查詢表a,顯示name列,并添加地址列,其列值都為'唐山'
4.1.6【查詢返回限制行數(關鍵字:top percent)】
例1:select top 6 name from a
說明:查詢表a,顯示列name的前6行,top為關鍵字
例 2:select top 60 percent name from a
說明:查詢表a,顯示列name的60%,percent為關鍵字
4.1.7【查詢排序(關鍵字:order by , asc , desc)】
例:select name
from a?where chengji >= 60?order by desc
說明:查詢a表中chengji大于等于60的所有行,并按降序顯示name列;默認為ASC升序
4.2 ''模糊查詢
4.2.1【使用like進行模糊查詢】
注意:like運算副只用于字符串,所以僅與char和varchar數據類型聯合使用
例:select * from a where name like '趙%'
說明:查詢顯示表a中,name字段第一個字為趙的記錄
4.2.2【使用between在某個范圍內進行查詢】
例:select * from a where nianling between 18 and 20
說明:查詢顯示表a中nianling在18到20之間的記錄
4.2.3【使用in在列舉值內進行查詢】
例:select name from a where address in ('北京','上海','唐山')
說明:查詢表a中address值為北京或者上海或者唐山的記錄,顯示name字段
4.3.分組查詢
4.3.1【使用group by進行分組from score (注釋:這里的score是表名)
group by studentID
說明:在表score中查詢,按strdentID字段分組,顯示strdentID字段和score字段的平均值;select語句中只允許被分組的列和為每個分組返回的一個值的表達式,例如用一個列名作為參數的聚合
4.3.2【使用having子句進行分組篩選】
例:select studentID as 學員編號,AVG(score) as 平均成績?(注釋:這里的score是列名)
from score (注釋:這里的score是表名)
group?by studentID
having count(score)>1
說明:接上面例子,顯示分組后count(score)>1的行,由于where只能在沒有分組時使用,分組后只能使用having來限制條件。
4.4.多表聯接查詢
4.4.1內聯接
4.4.1.1【在where子句中指定聯接條件】
例:select a.name,b.chengji
from a,b?where a.name=b.name
說明:查詢表a和表b中name字段相等的記錄,并顯示表a中的name字段和表b中的chengji字段
4.4.1.2【在from子句中使用join…on】
例:select a.name,b.chengji
from a inner join b?on (a.name=b.name)
說明:同上
4.4.2外聯接
4.4.2.1【左外聯接查詢】
例:select s.name,c.courseID,c.score
from strdents as s
left outer join score as c
on s.scode=c.strdentID
說明:在strdents表和score表中查詢滿足on條件的行,條件為score表的strdentID與strdents表中的sconde相同
4.4.2.2【右外聯接查詢】
例:select s.name,c.courseID,c.score
from strdents as s
right outer join score as c
on s.scode=c.strdentID
說明:在strdents表和score表中查詢滿足on條件的行,條件為strdents表中的sconde與score表的strdentID相同
5、常用的SQL語句總結如下:
SQL語法
1、查詢數據
基本查詢:SELECT * FROM
SELECT * FROM students; #查詢students表的所有數據
SELECT * FROM classes; #查詢classes表的所有數據
SELECT 100+200; #計算100+200
條件查詢:SELECT * FROM WHERE
SELECT * FROM students WHERE score >= 80; #按條件查詢students
SELECT * FROM students WHERE score >= 80 AND gender = 'M'; #按AND條件查詢students:
SELECT * FROM students WHERE score >= 80 OR gender = 'M'; #按OR條件查詢students:
SELECT * FROM students WHERE NOT class_id = 2; #按NOT條件查詢students:
SELECT * FROM students WHERE (score < 80 OR score > 90) AND gender = 'M'; #按多個條件查詢students:
投影查詢:SELECT 列1, 列2, 列3 FROM
SELECT id, score, name FROM students; #使用投影查詢
SELECT id, score points, name FROM students; #使用投影查詢,并將列名重命名:
SELECT id, score points, name FROM students WHERE gender = 'M'; #使用投影查詢+WHERE條件:
排序:SELECT * FROM ORDER BY
SELECT id, name, gender, score FROM students ORDER BY score; #按score從低到高
SELECT id, name, gender, score FROM students ORDER BY score DESC; #按score從高到低
SELECT id, name, gender, score FROM students ORDER BY score DESC, gender; #按score, gender排序:
SELECT id, name, gender, score FROM students WHERE class_id = 1 ORDER BY score DESC; #帶WHERE條件的ORDER BY:
分頁查詢:SELECT * FROM LIMIT OFFSET LIMIT總是設定為pageSize、OFFSET計算公式為pageSize * (pageIndex - 1)。
SELECT id, name, gender, score FROM students ORDER BY score DESC LIMIT 3 OFFSET 0; # 查詢第1頁,每頁3條記錄
SELECT id, name, gender, score FROM students ORDER BY score DESC LIMIT 3 OFFSET 3; #查詢第2頁,每頁3條記錄
SELECT id, name, gender, score FROM students ORDER BY score DESC LIMIT 3 OFFSET 6; #查詢第3頁,每頁3條記錄
SELECT id, name, gender, score FROM students ORDER BY score DESC LIMIT 3 OFFSET 20; #OFFSET設定為20
聚合查詢:SELECT FUCTIONNAME(*) FROM FUCTIONNAME: COUNT、SUM、AVG、MAX、MIN等
SELECT COUNT(*) FROM students; #使用聚合查詢,COUNT(*)表示查詢所有列的行數
SELECT COUNT(*) num FROM students; #使用聚合查詢并設置結果集的列名為num:
SELECT COUNT(*) boys FROM students WHERE gender = 'M'; #使用聚合查詢并設置WHERE條件:
SELECT AVG(score) average FROM students WHERE gender = 'M'; #使用聚合查詢計算男生平均成績:
SELECT COUNT(*) num FROM students GROUP BY class_id; #按class_id分組:
SELECT class_id, COUNT(*) num FROM students GROUP BY class_id; #按class_id分組:
多表查詢:SELECT * FROM ,
SELECT * FROM students, classes; #FROM students, classes: #FROM students, classes:
SELECT students.id sid,students.name, students.gender,classes.id cid,classes.name cname FROM students, classes; # set alias:
SELECT s.id sid,s.name,s.gender,c.id cid,c.name cname FROM students s, classes c; #set table alias:
SELECT s.id sid,s.name,s.gender,c.id cid,c.name cname FROM students s, classes c WHERE s.gender = 'M' AND c.id = 1; #set where clause:
連接查詢:SELECT ... FROM INNER JOIN ON ;
SELECT s.id, s.name, s.class_id, s.gender, s.score FROM students s; #選出所有學生
SELECT s.id, s.name, s.class_id, c.name class_name, s.score FROM students s INNER JOIN classes c ON s.class_id = c.id; #選出所有學生,同時返回班級名稱
2、修改數據
INSERT插入:INSERT INTO (字段1, 字段2, ...) VALUES (值1, 值2, ...);
INSERT INTO students (class_id, name, gender, score) VALUES (2, '大牛', 'M', 80); #添加一條新記錄
INSERT INTO students (class_id, name, gender, score) VALUES (1, '大寶', 'M', 87), (2, '二寶', 'M', 81); #一次性添加多條新記錄
插入或替換:如果記錄已經存在,就先刪除原記錄,再插入新記錄
REPLACE INTO students (id, class_id, name, gender, score) VALUES (1, 1, '小明', 'F', 99);
插入或更新:如果記錄已經存在,就更新該記錄,
INSERT INTO students (id, class_id, name, gender, score) VALUES (1, 1, '小明', 'F', 99) ON DUPLICATE KEY UPDATE name='小明', gender='F', score=99;
插入或忽略:若id=1的記錄不存在,INSERT語句將插入新記錄,否則,當前id=1的記錄將被更新
INSERT IGNORE INTO students (id, class_id, name, gender, score) VALUES (1, 1, '小明', 'F', 99);
UPDATE更新:UPDATE SET 字段1=值1, 字段2=值2, ... WHERE ...;
UPDATE students SET name='大牛', score=66 WHERE id=1; #更新id=1的記錄
UPDATE students SET name='小牛', score=77 WHERE id>=5 AND id<=7; #更新id=5,6,7的記錄
UPDATE students SET score=score+10 WHERE score<80; #更新score<80的記錄
UPDATE students SET score=100 WHERE id=999; #更新id=999的記錄
DELETE刪除:DELETE FROM WHERE ...;
DELETE FROM students WHERE id=1; #刪除id=1的記錄
DELETE FROM students WHERE id>=5 AND id<=7; #刪除id=5,6,7的記錄
DELETE FROM students WHERE id=999; #刪除id=999的記錄
總結:
創建
CREATE TABLE IF NOT EXSITE( 字段1 數據類型, 字段2 數據類型, 字段3 數據類型, ....)
CREAT TABLE if not exists 〈表名〉(id integerPrimary Key Autoincrement, sId integer, sName text, sAge integer)
查詢
SELECT * FROM WHERE
插入
INSERT INTO (字段1, 字段2, ...) VALUES (值1, 值2, ...);
替換
REPLACE INTO (字段1, 字段2, ...) VALUES (值1, 值2, ...);
更新
UPDATE SET 字段1=值1, 字段2=值2, ... WHERE ...;
刪除
DELETE FROM WHERE ...;