MySQL之基本查詢(一)(插入、查詢全列、指定列、where子句條件)

插入
1.insert
語法：

INSERT [INTO] table_name
     [(column [, column] ...)]
     VALUES (value_list) [, (value_list)] ...
      value_list: value, [, value] ...

• 案例
  先創建一張學生表

mysql> create table student(
    -> id int unsigned primary key auto_increment,
    -> sn int not null unique comment '學號',
    -> name varchar(20) not null,
    -> qq varchar(20));

1.1單行插入+全列插入

mysql> insert into student values(100,1000,'唐三藏',null);
mysql> insert into student VALUES (101, 1001, '孫悟空', '11111');
//查看插入的結果
mysql> select * from student;
+-----+------+-----------+-------+
| id  | sn   | name      | qq    |
+-----+------+-----------+-------+
| 100 | 1000 | 唐三藏    | NULL  |
| 101 | 1001 | 孫悟空    | 11111 |
+-----+------+-----------+-------+

1.2多行插入+指定列插入

mysql> insert into student (id,sn,name) values
    -> (102,2001,'曹孟德'),
    -> (103,2002,'孫仲謀');

mysql> select * from student;
+-----+------+-----------+-------+
| id  | sn   | name      | qq    |
+-----+------+-----------+-------+
| 100 | 1000 | 唐三藏    | NULL  |
| 101 | 1001 | 孫悟空    | 11111 |
| 102 | 2001 | 曹孟德    | NULL  |
| 103 | 2002 | 孫仲謀    | NULL  |
+-----+------+-----------+-------+

注意：value_list 的數量和順序與指定列的數量和順序必須一致。

1.3插入否則更新記錄
由於主鍵或者唯一值對應的值已經存在而導致插入失敗

//主鍵衝突導致插入失敗
mysql> insert into student(id,sn,name) values(100,1010,'唐xx');
ERROR 1062 (23000): Duplicate entry '100' for key 'PRIMARY'

//唯一鍵衝突導致插入失敗
mysql> insert into student(sn,name) values(2001,'曹xx');
ERROR 1062 (23000): Duplicate entry '2001' for key 'sn'

1.4替換
主鍵或者唯一鍵衝突，刪除後再插入

mysql> REPLACE INTO student(sn, name) VALUES (2001, '曹阿瞞');
Query OK, 2 rows affected (0.01 sec)
//2 rows affected表示表中有衝突數據，刪除後重新插入

1.5插入有要求
insert into:插入數據,如果主鍵重複，則報錯
insert repalce:插入替換數據,如果存在主鍵或unique數據則替換數據
insert or ignore:如果存在數據,則忽略。
2.查詢
語法：

SELECT
[DISTINCT] {* | {column [, column] ...}
[FROM table_name]
[WHERE ...]
[ORDER BY column [ASC | DESC], ...]
LIMIT ...

案例：

mysql> CREATE TABLE exam_result (
    -> id INT UNSIGNED PRIMARY KEY AUTO_INCREMENT,
    -> name VARCHAR(20) NOT NULL COMMENT '同學姓名',
    -> yuwen float DEFAULT 0.0 COMMENT '語文成績',
    -> shuxue float DEFAULT 0.0 COMMENT '數學成績',
    -> yingyu float DEFAULT 0.0 COMMENT '英語成績');

mysql> INSERT INTO exam_result (name, yuwen, shuxue, yingyu) VALUES
    -> ('唐三藏', 67, 98, 56),
    -> ('孫悟空', 87, 78, 77),
    -> ('豬悟能', 88, 98, 90),
    -> ('曹孟德', 82, 84, 67),
    -> ('劉玄德', 55, 85, 45),
    -> ('孫權', 70, 73, 78),
    -> ('宋公明', 75, 65, 30);

2.1SELECT列
2.1.1全列查詢

mysql> select * from exam_result;
+----+-----------+-------+--------+--------+
| id | name      | yuwen | shuxue | yingyu |
+----+-----------+-------+--------+--------+
|  1 | 唐三藏    |    67 |     98 |     56 |
|  2 | 孫悟空    |    87 |     78 |     77 |
|  3 | 豬悟能    |    88 |     98 |     90 |
|  4 | 曹孟德    |    82 |     84 |     67 |
|  5 | 劉玄德    |    55 |     85 |     45 |
|  6 | 孫權      |    70 |     73 |     78 |
|  7 | 宋公明    |    75 |     65 |     30 |
+----+-----------+-------+--------+--------+

2.1.2指定列查詢

mysql> select id,name,yingyu from exam_result;
+----+-----------+--------+
| id | name      | yingyu |
+----+-----------+--------+
|  1 | 唐三藏    |     56 |
|  2 | 孫悟空    |     77 |
|  3 | 豬悟能    |     90 |
|  4 | 曹孟德    |     67 |
|  5 | 劉玄德    |     45 |
|  6 | 孫權      |     78 |
|  7 | 宋公明    |     30 |
+----+-----------+--------+

2.1.3查詢字段爲表達式

//給所有人英語成績加10分
mysql> select id,name,yingyu+10 from exam_result;
+----+-----------+-----------+
| id | name      | yingyu+10 |
+----+-----------+-----------+
|  1 | 唐三藏    |        66 |
|  2 | 孫悟空    |        87 |
|  3 | 豬悟能    |       100 |
|  4 | 曹孟德    |        77 |
|  5 | 劉玄德    |        55 |
|  6 | 孫權      |        88 |
|  7 | 宋公明    |        40 |
+----+-----------+-----------+

//表達式包含多個字段
//查詢所有人的總成績
mysql> select id,name,yuwen+shuxue+yingyu from exam_result;
+----+-----------+---------------------+
| id | name      | yuwen+shuxue+yingyu |
+----+-----------+---------------------+
|  1 | 唐三藏    |                 221 |
|  2 | 孫悟空    |                 242 |
|  3 | 豬悟能    |                 276 |
|  4 | 曹孟德    |                 233 |
|  5 | 劉玄德    |                 185 |
|  6 | 孫權      |                 221 |
|  7 | 宋公明    |                 170 |
+----+-----------+---------------------+

2.1.4爲查詢結果指定別
語法：

SELECT column [AS] name [...] FROM table_name;

mysql> select id,name,yuwen+shuxue+yingyu as 總分 from exam_result;
+----+-----------+--------+
| id | name      | 總分   |
+----+-----------+--------+
|  1 | 唐三藏    |    221 |
|  2 | 孫悟空    |    242 |
|  3 | 豬悟能    |    276 |
|  4 | 曹孟德    |    233 |
|  5 | 劉玄德    |    185 |
|  6 | 孫權      |    221 |
|  7 | 宋公明    |    170 |
+----+-----------+--------+

2.1.5查詢結果去重

//數學成績裏98分重複
mysql> select shuxue from exam_result;
+--------+
| shuxue |
+--------+
|     98 |
|     78 |
|     98 |
|     84 |
|     85 |
|     73 |
|     65 |
+--------+

//去重之後的結果
mysql> select distinct shuxue from exam_result;
+--------+
| shuxue |
+--------+
|     98 |
|     78 |
|     84 |
|     85 |
|     73 |
|     65 |
+--------+

2.2WHERE條件
2.2.1比較運算符：
1)>,>=,<,<=(大於，大於等於，小於，小於等於)
2)！=，<>不等於
3)BETWEEN a0 AND a1(範圍匹配，[a0,a1])
4)IN(option,……)如果是option中的任意一個，返回TRUE(1)
5)IS NULL，IS NOT NULL
6)LIKE模糊匹配(%表示任意多個字符；_表示任意一個字符)
2.2.2運算符
1)AND:多個條件都爲true，結果才爲true
2)OR:任意一個條件爲true，結果爲true
3)NOT:條件爲true，結果爲false

案例：
2.2.3英語不及格的同學及英語成績

mysql> select name,yingyu from exam_result where yingyu<60;
+-----------+--------+
| name      | yingyu |
+-----------+--------+
| 唐三藏    |     56 |
| 劉玄德    |     45 |
| 宋公明    |     30 |
+-----------+--------+

2.2.4語文成績在[80,90]分的同學及語文成績

mysql> select name,yuwen from exam_result where yuwen between 80 and 90;
+-----------+-------+
| name      | yuwen |
+-----------+-------+
| 孫悟空    |    87 |
| 豬悟能    |    88 |
| 曹孟德    |    82 |
+-----------+-------+

2.2.5查詢數學成績是58或者59或者99或者98分的同學及數學成績

mysql> select name,shuxue from exam_result
    -> where shuxue=58 or shuxue=59 or shuxue=90
    -> or shuxue=98 or shuxue=99;
+-----------+--------+
| name      | shuxue |
+-----------+--------+
| 唐三藏    |     98 |
| 豬悟能    |     98 |
+-----------+--------+
2 rows in set (0.00 sec)

或者使用IN條件

mysql> select name,shuxue from exam_result where shuxue IN(58,59,98,99);
+-----------+--------+
| name      | shuxue |
+-----------+--------+
| 唐三藏    |     98 |
| 豬悟能    |     98 |
+-----------+--------+

2.2.6姓孫的同學及孫某同學

mysql> SELECT name FROM exam_result WHERE name LIKE '孫%';
//或者使用_字符
mysql> SELECT name FROM exam_result WHERE name LIKE '孫_';
+-----------+
| name      |
+-----------+
| 孫悟空    |
| 孫權      |
+-----------+
+-----------+
| name      |
+-----------+
| 孫悟空    |
| 孫權      |
+-----------+

2.2.7語文成績比英語成績的同學

mysql> SELECT name, yuwen, yingyu FROM exam_result WHERE yuwen > yingyu;
+-----------+-------+--------+
| name      | yuwen | yingyu |
+-----------+-------+--------+
| 唐三藏    |    67 |     56 |
| 孫悟空    |    87 |     77 |
| 曹孟德    |    82 |     67 |
| 劉玄德    |    55 |     45 |
| 宋公明    |    75 |     30 |
+-----------+-------+--------+

2.2.8總分在200分以下的同學

mysql> select id,name,yuwen+shuxue+yingyu as 總分 from exam_result
    -> where yuwen+shuxue+yingyu <200;
+----+-----------+--------+
| id | name      | 總分   |
+----+-----------+--------+
|  5 | 劉玄德    |    185 |
|  7 | 宋公明    |    170 |
+----+-----------+--------+

2.2.9語文成績>80且不姓孫的同學

mysql> select name,yuwen from exam_result
    -> where yuwen> 80 and  name not like '孫%';
+-----------+-------+
| name      | yuwen |
+-----------+-------+
| 豬悟能    |    88 |
| 曹孟德    |    82 |
+-----------+-------+

2.2.10孫某同學，否則要求總成績>200並且 語文成績<數學成績並且英語成績>80

mysql> SELECT name, yuwen, shuxue, yingyu, yuwen + shuxue + yingyu 總分
    -> FROM exam_result
    -> WHERE name LIKE '孫_' OR (
    -> yuwen + shuxue + yingyu > 200 AND yuwen < shuxue AND yingyu > 80
    -> );
+-----------+-------+--------+--------+--------+
| name      | yuwen | shuxue | yingyu | 總分   |
+-----------+-------+--------+--------+--------+
| 豬悟能    |    88 |     98 |     90 |    276 |
| 孫權      |    70 |     73 |     78 |    221 |
+-----------+-------+--------+--------+--------+