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這篇文章主要介紹“MYSQL表的全面分析”，在日常操作中，相信很多人在MYSQL表的全面分析問題上存在疑惑，小編查閱了各式資料，整理出簡單好用的操作方法，希望對大家解答”MYSQL表的全面分析”的疑惑有所幫助！接下來，請跟著小編一起來學習吧！
CREATE TABLE tablename (column_name_1 column_type_1 constraints， column_name_2 column_type_2 constraints ， ……）
column_name 是列的名字column_type 是列的數據類型contraints 是這個列的約束條件
mysql> create table orders (ordername varchar(10),createtime date,ordermoney decimal(10,2),ordernumber int(2)); Query OK, 0 rows affected (0.23 sec)
結構化定義：
mysql> desc orders; +-------------+---------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------------+---------------+------+-----+---------+-------+ | ordername | varchar(10) | YES | | NULL | | | createtime | date | YES | | NULL | | | ordermoney | decimal(10,2) | YES | | NULL | | | ordernumber | int(2) | YES | | NULL | | +-------------+---------------+------+-----+---------+-------+ 4 rows in set (0.00 sec)
表詳細定義：
查看詳細的表定義：
mysql> show create table orders \G; *************************** 1. row *************************** Table: orders Create Table: CREATE TABLE `orders` ( `ordername` varchar(10) DEFAULT NULL, `createtime` date DEFAULT NULL, `ordermoney` decimal(10,2) DEFAULT NULL, `ordernumber` int(2) DEFAULT NULL ) ENGINE=InnoDB DEFAULT CHARSET=latin1 1 row in set (0.00 sec) ERROR: No query specified
由此可以看到表的 ENGINE（存儲引擎）是InnoDB
CHARSET（字符集）是Latin1
“\G”選項的含義是使得記錄能夠按照字段豎著排列，對于內容比較長的記錄更易于顯示。
命令：
DROP TABLE tablename
刪除orders：
mysql> drop table orders -> ; Query OK, 0 rows affected (0.14 sec)
ALTER TABLE tablename MODIFY [COLUMN] column_definition [FIRST | AFTER col_name]
例：修改表 orders 的 name 字段定義，將 varchar(10)改為 varchar(20) ：
mysql> alter table orders modify ordername varchar(20); Query OK, 0 rows affected (0.11 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> desc orders; +-------------+---------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------------+---------------+------+-----+---------+-------+ | ordername | varchar(20) | YES | | NULL | | | createtime | date | YES | | NULL | | | ordermoney | decimal(10,2) | YES | | NULL | | | ordernumber | int(2) | YES | | NULL | | +-------------+---------------+------+-----+---------+-------+ 4 rows in set (0.00 sec)
ALTER TABLE tablename CHANGE [COLUMN] old_col_name column_definition [FIRST|AFTER col_name]
例：表 orders 上將ordernumber修改為ordernumbers
mysql> alter table orders change column ordernumber ordernumbers int(4); Query OK, 0 rows affected (0.06 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> desc orders; +--------------+---------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +--------------+---------------+------+-----+---------+-------+ | ordername | varchar(20) | YES | | NULL | | | createtime | date | YES | | NULL | | | ordermoney | decimal(10,2) | YES | | NULL | | | ordernumbers | int(4) | YES | | NULL | | +--------------+---------------+------+-----+---------+-------+ 4 rows in set (0.00 sec)
特別說明：change 和 modify 都可以修改表的定義，不同的是 change 后面需要寫兩次列名，不方便。但是 change 的優點是可以修改列名稱，modify 則不能。
ALTER TABLE tablename ADD [COLUMN] column_definition [FIRST | AFTER col_name]
例：表 orders 上新增加字段 username，類型為 varchar(3) ：
mysql> alter table orders add column username varchar(30); Query OK, 0 rows affected (0.39 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> desc orders; +-------------+---------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------------+---------------+------+-----+---------+-------+ | ordername | varchar(20) | YES | | NULL | | | createtime | date | YES | | NULL | | | ordermoney | decimal(10,2) | YES | | NULL | | | ordernumber | int(2) | YES | | NULL | | | username | varchar(30) | YES | | NULL | | +-------------+---------------+------+-----+---------+-------+ 5 rows in set (0.00 sec)
ALTER TABLE tablename DROP [COLUMN] col_name
例：表 orders 上刪除字段 username：
mysql> alter table orders drop column username; Query OK, 0 rows affected (0.53 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> desc orders; +-------------+---------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------------+---------------+------+-----+---------+-------+ | ordername | varchar(20) | YES | | NULL | | | createtime | date | YES | | NULL | | | ordermoney | decimal(10,2) | YES | | NULL | | | ordernumber | int(2) | YES | | NULL | | +-------------+---------------+------+-----+---------+-------+ 4 rows in set (0.00 sec)
ALTER TABLE tablename RENAME [TO] new_tablename
例：表 orders 名字改為goodsorders
mysql> alter table orders rename goodsorders; Query OK, 0 rows affected (0.16 sec) mysql> desc orders; ERROR 1146 (42S02): Table 'ordermanage.orders' doesn't exist mysql> desc goodsorders; +--------------+---------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +--------------+---------------+------+-----+---------+-------+ | ordername | varchar(20) | YES | | NULL | | | createtime | date | YES | | NULL | | | ordermoney | decimal(10,2) | YES | | NULL | | | ordernumbers | int(4) | YES | | NULL | | +--------------+---------------+------+-----+---------+-------+ 4 rows in set (0.00 sec)
插入（insert）、查詢（select）、更新（update）、刪除（delete）
INSERT INTO tablename (field1,field2,……fieldn) VALUES(value1,value2,……valuesn);
例：表 goodsorders 中插入一條記錄，ordername 為zhang，createtime為2021-05-12，ordermoney為100.00,ordernumbers為：1
mysql> insert into goodsorders (ordername,createtime,ordermoney,ordernumbers) values('zhang','2021-05-12',100.00,1);
Query OK, 1 row affected (0.03 sec)也可以省略(field1,field2,……fieldn)這一部分
mysql> insert into goodsorders values('zhang1','2021-05-12',1001.00,11);
Query OK, 1 row affected (0.05 sec)SELECT * FROM tablename [WHERE CONDITION]
例：查看goodsorders中所有插入數據
mysql> select * from goodsorders; +-----------+------------+------------+--------------+ | ordername | createtime | ordermoney | ordernumbers | +-----------+------------+------------+--------------+ | zhang | 2021-05-12 | 100.00 | 1 | | zhang1 | 2021-05-12 | 1001.00 | 11 | +-----------+------------+------------+--------------+ 2 rows in set (0.00 sec)
其中“*”表示要將所有的記錄都選出來
distinct
例：查詢非goodsorders中非重復創建時間（createtime）的數據
mysql> select * from goodsorders; +-----------+------------+------------+--------------+ | ordername | createtime | ordermoney | ordernumbers | +-----------+------------+------------+--------------+ | zhang | 2021-03-11 | 50.00 | 1 | | li | 2020-05-12 | 70.00 | 15 | | li | 2020-03-12 | 70.00 | 15 | | li | 2020-03-11 | 70.00 | 15 | | li | 2021-03-11 | 70.00 | 15 | +-----------+------------+------------+--------------+ 5 rows in set (0.00 sec) mysql> select distinct createtime from goodsorders; +------------+ | createtime | +------------+ | 2021-03-11 | | 2020-05-12 | | 2020-03-12 | | 2020-03-11 | +------------+ 4 rows in set (0.00 sec)
由此可以看到，將重復的一條時間數據2021-03-11去掉了
where 后面的條件是一個字段的‘='比較，還可以使用>、<、>=、<=、!=等比較運算符；
多個條件之間還可以使用 or、and 等邏輯運算符進行多條件聯合查詢，
例：查詢非goodsorders中 ordername='li'并且createtime為2020-03-11
mysql> select * from goodsorders where ordername='li'and createtime ='2020-03-11'; +-----------+------------+------------+--------------+ | ordername | createtime | ordermoney | ordernumbers | +-----------+------------+------------+--------------+ | li | 2020-03-11 | 70.00 | 15 | +-----------+------------+------------+--------------+ 1 row in set (0.00 sec)
SELECT * FROM tablename [WHERE CONDITION] [ORDER BY field1 [DESC|ASC] ， field2 [DESC|ASC]，……fieldn [DESC|ASC]]
例：把 goodsorders表中的記錄按照創建時間高低進行排序顯示
mysql> select * from goodsorders order by createtime; +-----------+------------+------------+--------------+ | ordername | createtime | ordermoney | ordernumbers | +-----------+------------+------------+--------------+ | li | 2020-03-11 | 70.00 | 15 | | li | 2020-03-12 | 70.00 | 15 | | li | 2020-05-12 | 70.00 | 15 | | zhang | 2021-03-11 | 50.00 | 1 | | li | 2021-03-11 | 70.00 | 15 | +-----------+------------+------------+--------------+ 5 rows in set (0.01 sec)
SELECT ……[LIMIT offset_start,row_count]
offset_start 表示記錄的起始偏移量row_count 表示顯示的行數
例如1：顯示 goodsorders表中按照 createtiem 排序后的前 3 條記錄：
mysql> select * from goodsorders order by createtime limit 3; +-----------+------------+------------+--------------+ | ordername | createtime | ordermoney | ordernumbers | +-----------+------------+------------+--------------+ | li | 2020-03-11 | 70.00 | 15 | | li | 2020-03-12 | 70.00 | 15 | | li | 2020-05-12 | 70.00 | 15 | +-----------+------------+------------+--------------+ 3 rows in set (0.00 sec)
例如2：如果要顯示 goodsorders表中按照 createtiem 排序后 從第二條記錄開始，顯示3條數據：
mysql> select * from goodsorders order by createtime limit 2,3; +-----------+------------+------------+--------------+ | ordername | createtime | ordermoney | ordernumbers | +-----------+------------+------------+--------------+ | li | 2020-05-12 | 70.00 | 15 | | zhang | 2021-03-11 | 50.00 | 1 | | li | 2021-03-11 | 70.00 | 15 | +-----------+------------+------------+--------------+ 3 rows in set (0.00 sec)
SELECT [field1,field2,……fieldn] fun_name FROM tablename [WHERE where_contition] [GROUP BY field1,field2,……fieldn [WITH ROLLUP]] [HAVING where_contition]
參數說明：
1、fun_name 表示要做的聚合操作，也就是聚合函數，常用的有 sum（求和）、count(*)（記錄數）、max（最大值）、min（最小值）
2、GROUP BY 關鍵字表示要進行分類聚合的字段，比如要按照部門分類統計員工數量，部門就應該寫在 group by 后面。
3、WITH ROLLUP 是可選語法，表明是否對分類聚合后的結果進行再匯總。
4、HAVING 關鍵字表示對分類后的結果再進行條件的過濾。
注意：having 和 where 的區別在于 having 是對聚合后的結果進行條件的過濾，而 where 是在聚合前就對記錄進行過濾，如果邏輯允許，我們盡可能用 where 先過濾記錄，這樣因為結果集減小，將對聚合的效率大大提高，最后再根據邏輯看是否用 having 進行再過濾。
例1：查詢統計goodsorders表中，記錄總數
mysql> select count(1) from goodsorders; +----------+ | count(1) | +----------+ | 5 | +----------+ 1 row in set (0.00 sec)
例2：在此基礎上，按照創建日期（createtime）進行分組統計
mysql> select createtime,count(1) from goodsorders group by createtime; +------------+----------+ | createtime | count(1) | +------------+----------+ | 2020-03-11 | 1 | | 2020-03-12 | 1 | | 2020-05-12 | 1 | | 2021-03-11 | 2 | +------------+----------+ 4 rows in set (0.00 sec)
例3：在此基礎上，既要按照創建日期（cretetime）進行分組統計，又要計算總數
mysql> select createtime,count(1) from goodsorders group by createtime with rollup; +------------+----------+ | createtime | count(1) | +------------+----------+ | 2020-03-11 | 1 | | 2020-03-12 | 1 | | 2020-05-12 | 1 | | 2021-03-11 | 2 | | NULL | 5 | +------------+----------+ 5 rows in set (0.02 sec)
最有一行，null所展示的數字，就是總數
例4：按照創建日期（createtime）進行分組統計，并且數量大于1
mysql> select createtime,count(1) from goodsorders group by createtime having count(1)>1; +------------+----------+ | createtime | count(1) | +------------+----------+ | 2021-03-11 | 2 | +------------+----------+ 1 row in set (0.00 sec)
例5：查詢goodsorders表中，訂單金額（ordermoney）的總額、最低額、最高額
mysql> select * from goodsorders; +-----------+------------+------------+--------------+ | ordername | createtime | ordermoney | ordernumbers | +-----------+------------+------------+--------------+ | zhang | 2021-03-11 | 50.00 | 1 | | li | 2020-05-12 | 70.00 | 15 | | li | 2020-03-12 | 70.00 | 15 | | li | 2020-03-11 | 70.00 | 15 | | li | 2021-03-11 | 70.00 | 15 | +-----------+------------+------------+--------------+ 5 rows in set (0.00 sec) mysql> select sum(ordermoney),max(ordermoney),min(ordermoney) from goodsorders; +-----------------+-----------------+-----------------+ | sum(ordermoney) | max(ordermoney) | min(ordermoney) | +-----------------+-----------------+-----------------+ | 330.00 | 70.00 | 50.00 | +-----------------+-----------------+-----------------+ 1 row in set (0.02 sec)
1、左連接：包含所有的左邊表中的記錄甚至是右邊表中沒有和它匹配的記錄；關鍵指令：left join
2、右連接：包含所有的右邊表中的記錄甚至是左邊表中沒有和它匹配的記錄；關聯指令：right join
例1：現在我們又創建一張用戶表（member）,使用goodorders進行左連接，查詢關聯的用戶表信息
mysql> select * from member; +------+------------+ | id | membername | +------+------------+ | 15 | zhang | | 1 | li | | 13 | liss | +------+------------+ 3 rows in set (0.00 sec) mysql> select * from goodsorders; +-----------+------------+------------+--------------+----------+ | ordername | createtime | ordermoney | ordernumbers | memberid | +-----------+------------+------------+--------------+----------+ | zhang | 2021-03-11 | 50.00 | 1 | 15 | | li | 2020-05-12 | 70.00 | 15 | 1 | | li | 2020-03-12 | 70.00 | 15 | 1 | | li | 2020-03-11 | 70.00 | 15 | 3 | | li | 2021-03-11 | 70.00 | 15 | 1 | +-----------+------------+------------+--------------+----------+ 5 rows in set (0.00 sec) mysql> select * from goodsorders left join member on goodsorders.memberid = member.id; +-----------+------------+------------+--------------+----------+------+------------+ | ordername | createtime | ordermoney | ordernumbers | memberid | id | membername | +-----------+------------+------------+--------------+----------+------+------------+ | zhang | 2021-03-11 | 50.00 | 1 | 15 | 15 | zhang | | li | 2020-05-12 | 70.00 | 15 | 1 | 1 | li | | li | 2020-03-12 | 70.00 | 15 | 1 | 1 | li | | li | 2021-03-11 | 70.00 | 15 | 1 | 1 | li | | li | 2020-03-11 | 70.00 | 15 | 3 | NULL | NULL | +-----------+------------+------------+--------------+----------+------+------------+ 5 rows in set (0.00 sec)
例2：member和goodsorders中數據不變，我們再來看一下右連接的查詢，以及結果：
mysql> select * from goodsorders right join member on goodsorders.memberid = member.id; +-----------+------------+------------+--------------+----------+------+------------+ | ordername | createtime | ordermoney | ordernumbers | memberid | id | membername | +-----------+------------+------------+--------------+----------+------+------------+ | zhang | 2021-03-11 | 50.00 | 1 | 15 | 15 | zhang | | li | 2020-05-12 | 70.00 | 15 | 1 | 1 | li | | li | 2020-03-12 | 70.00 | 15 | 1 | 1 | li | | li | 2021-03-11 | 70.00 | 15 | 1 | 1 | li | | NULL | NULL | NULL | NULL | NULL | 13 | liss | +-----------+------------+------------+--------------+----------+------+------------+ 5 rows in set (0.00 sec)
這里發生了翻轉，變為左側goodsorders 表中的一條數據為空了
主要包括 in、not in、=、!=、exists、not exists 等
例：從goodsorders表中查詢所有用戶在memeber表中的記錄
mysql> select * from member; +------+------------+ | id | membername | +------+------------+ | 15 | zhang | | 1 | li | | 13 | liss | +------+------------+ 3 rows in set (0.00 sec) mysql> select * from goodsorders; +-----------+------------+------------+--------------+----------+ | ordername | createtime | ordermoney | ordernumbers | memberid | +-----------+------------+------------+--------------+----------+ | zhang | 2021-03-11 | 50.00 | 1 | 15 | | li | 2020-05-12 | 70.00 | 15 | 1 | | li | 2020-03-12 | 70.00 | 15 | 1 | | li | 2020-03-11 | 70.00 | 15 | 3 | | li | 2021-03-11 | 70.00 | 15 | 1 | +-----------+------------+------------+--------------+----------+ 5 rows in set (0.00 sec) mysql> select * from goodsorders where memberid in(select id from member); +-----------+------------+------------+--------------+----------+ | ordername | createtime | ordermoney | ordernumbers | memberid | +-----------+------------+------------+--------------+----------+ | zhang | 2021-03-11 | 50.00 | 1 | 15 | | li | 2020-05-12 | 70.00 | 15 | 1 | | li | 2020-03-12 | 70.00 | 15 | 1 | | li | 2021-03-11 | 70.00 | 15 | 1 | +-----------+------------+------------+--------------+----------+ 4 rows in set (0.05 sec)
SELECT * FROM t1 UNION|UNION ALL SELECT * FROM t2 …… UNION|UNION ALL SELECT * FROM tn;
UNION 和 UNION ALL 的主要區別：
UNION ALL 是把結果集直接合并在一起，
UNION 是將UNION ALL 后的結果進行一次 DISTINCT，去除重復記錄后的結果。
例1：將member表和goodsorders表中的用戶編號id（memberid）的集合顯示出來
mysql> select memberid from goodsorders union all select id from member; +----------+ | memberid | +----------+ | 15 | | 1 | | 1 | | 3 | | 1 | | 15 | | 1 | | 13 | +----------+ 8 rows in set (0.00 sec)
例2：如果希望將上面的結果去掉重復記錄后顯示
mysql> select memberid from goodsorders union select id from member; +----------+ | memberid | +----------+ | 15 | | 1 | | 3 | | 13 | +----------+ 4 rows in set (0.00 sec)
UPDATE tablename SET field1=value1，field2.=value2，……fieldn=valuen [WHERE CONDITION]
例：將表 goodsorders 中ordername為zhang的訂單金額（ordermoney）改為50
mysql> update goodsorders set ordermoney=50.00 where ordername='zhang'; Query OK, 1 row affected (0.09 sec) Rows matched: 1 Changed: 1 Warnings: 0 mysql> select * from goodsorders; +-----------+------------+------------+--------------+ | ordername | createtime | ordermoney | ordernumbers | +-----------+------------+------------+--------------+ | zhang | 2021-05-12 | 50.00 | 1 | | zhang1 | 2021-05-12 | 1001.00 | 11 | +-----------+------------+------------+--------------+ 2 rows in set (0.00 sec)
更新時，如遇到錯誤代碼1175：
Error Code: 1175. You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column. To disable safe mode, toggle the option in Preferences
解決方法：
1、先進行狀體查詢：
show variables like 'SQL_SAFE_UPDATES';
2、執行下面的sql，關閉safe-updates模式：
SET SQL_SAFE_UPDATES = 0;
或者
SET SQL_SAFE_UPDATES = false;
DELETE FROM tablename [WHERE CONDITION]
例：將表 goodsorders 中ordername為zhang1的記錄全部刪除
mysql> delete from goodsorders where ordername = 'zhang1'; Query OK, 1 row affected (0.06 sec) mysql> select * from goodsorders; +-----------+------------+------------+--------------+ | ordername | createtime | ordermoney | ordernumbers | +-----------+------------+------------+--------------+ | zhang | 2021-05-12 | 50.00 | 1 | +-----------+------------+------------+--------------+ 1 row in set (0.02 sec)
例：將表中的所有數據清空
mysql> select * from varc; +------+------+ | v | c | +------+------+ | abc | abc | +------+------+ 1 row in set (0.03 sec) mysql> truncate table varc; Query OK, 0 rows affected (0.25 sec) mysql> select * from varc; Empty set (0.00 sec)
DCL語句主要是為了管理數據庫系統中的操作對象權限
例：創建一個數據庫用戶 user1,初始密碼為123，具有對 ordermanage 數據庫中所有表的 SELECT/INSERT 權限：
mysql> grant select,insert on ordermanage.* to 'user1'@'localhost' identified by '123'; Query OK, 0 rows affected, 1 warning (0.06 sec) mysql> exit Bye C:\Program Files\MySQL\MySQL Server 5.7\bin>mysql -uuser1 -p123 mysql: [Warning] Using a password on the command line interface can be insecure. Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 82 Server version: 5.7.17-log MySQL Community Server (GPL) Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. mysql> show databases; +--------------------+ | Database | +--------------------+ | information_schema | | ordermanage | +--------------------+ 2 rows in set (0.00 sec)
在此基礎上，將此用戶（user1）的insert權限進行收回
mysql> revoke insert on ordermanage.* from 'user1'@'localhost';
Query OK, 0 rows affected (0.02 sec)
mysql> exit
Bye
C:\Program Files\MySQL\MySQL Server 5.7\bin>mysql -uuser1 -p123
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 84
Server version: 5.7.17-log MySQL Community Server (GPL)
Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> use ordermanage;
Database changed
mysql> insert into member values('11','ss');
ERROR 1142 (42000): INSERT command denied to user 'user1'@'localhost' for table 'member'
mysql>由此可以看出插入權限不足，插入失敗
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