高清无码一区二区在线观看吞精,亚洲va久久久噜噜噜久久天堂

主頁 > 知識庫 > mysql學(xué)習(xí)筆記之表的基本操作

mysql學(xué)習(xí)筆記之表的基本操作

創(chuàng)建表

create table 表名

create table if not exists 表名

mysql> create database company;
Query OK, 1 row affected (0.00 sec)
mysql> use company;
Database changed
mysql> create table if not exists t_dept(
  -> deptno int,
  -> dname varchar(20),
  -> loc varchar(40));
Query OK, 0 rows affected (0.20 sec)
mysql> show tables;
+-------------------+
| Tables_in_company |
+-------------------+
| t_dept      |
+-------------------+
1 row in set (0.00 sec)
mysql>

顯示當(dāng)前庫下的所有表

show tables;

mysql> show tables;
+-------------------+
| Tables_in_company |
+-------------------+
| t_dept      |
+-------------------+
1 row in set (0.00 sec)

查看表的結(jié)構(gòu)

describe 表名

簡寫

desc 表名

mysql> describe t_dept;
+--------+-------------+------+-----+---------+-------+
| Field | Type    | Null | Key | Default | Extra |
+--------+-------------+------+-----+---------+-------+
| deptno | int(11)   | YES |   | NULL  |    |
| dname | varchar(20) | YES |   | NULL  |    |
| loc  | varchar(40) | YES |   | NULL  |    |
+--------+-------------+------+-----+---------+-------+
3 rows in set (0.00 sec)
mysql> desc t_dept;
+--------+-------------+------+-----+---------+-------+
| Field | Type    | Null | Key | Default | Extra |
+--------+-------------+------+-----+---------+-------+
| deptno | int(11)   | YES |   | NULL  |    |
| dname | varchar(20) | YES |   | NULL  |    |
| loc  | varchar(40) | YES |   | NULL  |    |
+--------+-------------+------+-----+---------+-------+
3 rows in set (0.00 sec)

查看表的詳細(xì)

show create table 表名

mysql> show create table t_dept;
+--------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table                                                                            |
+--------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| t_dept | CREATE TABLE `t_dept` (
 `deptno` int(11) DEFAULT NULL,
 `dname` varchar(20) DEFAULT NULL,
 `loc` varchar(40) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8 |
+--------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
show create table t_dept \G

mysql> show create table t_dept \G
*************************** 1. row ***************************
    Table: t_dept
Create Table: CREATE TABLE `t_dept` (
 `deptno` int(11) DEFAULT NULL,
 `dname` varchar(20) DEFAULT NULL,
 `loc` varchar(40) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8
1 row in set (0.00 sec)

刪除表

drop table 表名
drop table if exists 表名

mysql> drop table if exists t_dept;
Query OK, 0 rows affected (0.12 sec)
mysql> show tables;
Empty set (0.00 sec)

修改表名

ALTER TABLE old_table_name RENAME [TO] new_table_name
old_table_name 原表名
new_table_name 新表名
將t_dept修改為tab_dept

mysql> alter table t_dept rename tab_dept;
Query OK, 0 rows affected (0.09 sec)
mysql> show tables;
+-------------------+
| Tables_in_company |
+-------------------+
| tab_dept     |
+-------------------+
1 row in set (0.00 sec)
mysql> desc tab_dept;
+--------+-------------+------+-----+---------+-------+
| Field | Type    | Null | Key | Default | Extra |
+--------+-------------+------+-----+---------+-------+
| deptno | int(11)   | YES |   | NULL  |    |
| dname | varchar(20) | YES |   | NULL  |    |
| loc  | varchar(40) | YES |   | NULL  |    |
+--------+-------------+------+-----+---------+-------+
3 rows in set (0.00 sec)

為表增加一個(gè)字段默認(rèn)在最后
ALTER TABLE table_name ADD 屬性名屬性類型

為tab_dept增加一個(gè)字段descri varchar(20)

mysql> desc tab_dept;
+--------+-------------+------+-----+---------+-------+
| Field | Type    | Null | Key | Default | Extra |
+--------+-------------+------+-----+---------+-------+
| deptno | int(11)   | YES |   | NULL  |    |
| dname | varchar(20) | YES |   | NULL  |    |
| loc  | varchar(40) | YES |   | NULL  |    |
+--------+-------------+------+-----+---------+-------+
3 rows in set (0.00 sec)
mysql> alter table tab_dept add descri varchar(20);
Query OK, 0 rows affected (0.33 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> desc tab_dept;
+--------+-------------+------+-----+---------+-------+
| Field | Type    | Null | Key | Default | Extra |
+--------+-------------+------+-----+---------+-------+
| deptno | int(11)   | YES |   | NULL  |    |
| dname | varchar(20) | YES |   | NULL  |    |
| loc  | varchar(40) | YES |   | NULL  |    |
| descri | varchar(20) | YES |   | NULL  |    |
+--------+-------------+------+-----+---------+-------+
4 rows in set (0.00 sec)

在表的第一個(gè)位置增加一個(gè)字段

ALTER TABLE table_name ADD 屬性名屬性類型 first

mysql> alter table tab_dept add id int first;
Query OK, 0 rows affected (0.38 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> desc tab_dept;
+--------+-------------+------+-----+---------+-------+
| Field | Type    | Null | Key | Default | Extra |
+--------+-------------+------+-----+---------+-------+
| id   | int(11)   | YES |   | NULL  |    |
| deptno | int(11)   | YES |   | NULL  |    |
| dname | varchar(20) | YES |   | NULL  |    |
| loc  | varchar(40) | YES |   | NULL  |    |
| descri | varchar(20) | YES |   | NULL  |    |
+--------+-------------+------+-----+---------+-------+
5 rows in set (0.00 sec)

在表的指定字段之后增加字段

ALTER TABLE table_name ADD 屬性名屬性類型 AFTER 屬性名

mysql> alter table tab_dept add comm varchar(20) after dname;
Query OK, 0 rows affected (0.31 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> desc tab_dept;
+--------+-------------+------+-----+---------+-------+
| Field | Type    | Null | Key | Default | Extra |
+--------+-------------+------+-----+---------+-------+
| id   | int(11)   | YES |   | NULL  |    |
| deptno | int(11)   | YES |   | NULL  |    |
| dname | varchar(20) | YES |   | NULL  |    |
| comm  | varchar(20) | YES |   | NULL  |    |
| loc  | varchar(40) | YES |   | NULL  |    |
| descri | varchar(20) | YES |   | NULL  |    |
+--------+-------------+------+-----+---------+-------+
6 rows in set (0.00 sec)

刪除字段

ALTER TABLE table_name DROP 屬性名

mysql> alter table tab_dept drop comm;
Query OK, 0 rows affected (0.32 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> desc tab_dept;
+--------+-------------+------+-----+---------+-------+
| Field | Type    | Null | Key | Default | Extra |
+--------+-------------+------+-----+---------+-------+
| id   | int(11)   | YES |   | NULL  |    |
| deptno | int(11)   | YES |   | NULL  |    |
| dname | varchar(20) | YES |   | NULL  |    |
| loc  | varchar(40) | YES |   | NULL  |    |
| descri | varchar(20) | YES |   | NULL  |    |
+--------+-------------+------+-----+---------+-------+
5 rows in set (0.00 sec)

字段修改-修改字段數(shù)據(jù)類型
ALTER TABLE table_name MODIFY 屬性名數(shù)據(jù)類型

mysql> alter table tab_dept modify descri int;
Query OK, 0 rows affected (0.45 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> desc tab_dept;
+--------+-------------+------+-----+---------+-------+
| Field | Type    | Null | Key | Default | Extra |
+--------+-------------+------+-----+---------+-------+
| id   | int(11)   | YES |   | NULL  |    |
| deptno | int(11)   | YES |   | NULL  |    |
| dname | varchar(20) | YES |   | NULL  |    |
| loc  | varchar(40) | YES |   | NULL  |    |
| descri | int(11)   | YES |   | NULL  |    |
+--------+-------------+------+-----+---------+-------+
5 rows in set (0.00 sec)

字段修改-修改字段名稱

ALTER TABLE table_name CHANGE 舊屬性名新屬性名舊數(shù)據(jù)類型

mysql> alter table tab_dept change id deptid int;
Query OK, 0 rows affected (0.07 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> desc tab_dept;
+--------+-------------+------+-----+---------+-------+
| Field | Type    | Null | Key | Default | Extra |
+--------+-------------+------+-----+---------+-------+
| deptid | int(11)   | YES |   | NULL  |    |
| deptno | int(11)   | YES |   | NULL  |    |
| dname | varchar(20) | YES |   | NULL  |    |
| loc  | varchar(40) | YES |   | NULL  |    |
| descri | int(11)   | YES |   | NULL  |    |
+--------+-------------+------+-----+---------+-------+
5 rows in set (0.00 sec)

字段修改-同時(shí)修改字段名稱與數(shù)據(jù)類型

ALTER TABLE table_name CHANGE 舊屬性名新屬性名新數(shù)據(jù)類型

mysql> alter table tab_dept change deptid id varchar(32);
Query OK, 0 rows affected (0.49 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> desc tab_dept;
+--------+-------------+------+-----+---------+-------+
| Field | Type    | Null | Key | Default | Extra |
+--------+-------------+------+-----+---------+-------+
| id   | varchar(32) | YES |   | NULL  |    |
| deptno | int(11)   | YES |   | NULL  |    |
| dname | varchar(20) | YES |   | NULL  |    |
| loc  | varchar(40) | YES |   | NULL  |    |
| descri | int(11)   | YES |   | NULL  |    |
+--------+-------------+------+-----+---------+-------+
5 rows in set (0.00 sec)

修改順序

ALTER TABLE table_name MODIFY 屬性名1 數(shù)據(jù)類型 FIRST|AFTER 屬性名2

2個(gè)屬性必須存在
將deptno調(diào)到第一個(gè)位置

mysql> alter table tab_dept modify deptno int first;
Query OK, 0 rows affected (0.33 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> desc tab_dept;
+--------+-------------+------+-----+---------+-------+
| Field | Type    | Null | Key | Default | Extra |
+--------+-------------+------+-----+---------+-------+
| deptno | int(11)   | YES |   | NULL  |    |
| id   | varchar(32) | YES |   | NULL  |    |
| dname | varchar(20) | YES |   | NULL  |    |
| loc  | varchar(40) | YES |   | NULL  |    |
| descri | int(11)   | YES |   | NULL  |    |
+--------+-------------+------+-----+---------+-------+
5 rows in set (0.00 sec)

將ID放在最后

mysql> alter table tab_dept modify deptno int after descri;
Query OK, 0 rows affected (0.29 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> desc tab_dept;
+--------+-------------+------+-----+---------+-------+
| Field | Type    | Null | Key | Default | Extra |
+--------+-------------+------+-----+---------+-------+
| id   | varchar(32) | YES |   | NULL  |    |
| dname | varchar(20) | YES |   | NULL  |    |
| loc  | varchar(40) | YES |   | NULL  |    |
| descri | int(11)   | YES |   | NULL  |    |
| deptno | int(11)   | YES |   | NULL  |    |
+--------+-------------+------+-----+---------+-------+
5 rows in set (0.00 sec)
mysql> alter table tab_dept modify deptno int first;
Query OK, 0 rows affected (0.34 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> alter table tab_dept modify id int after descri;
Query OK, 0 rows affected (0.47 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> desc tab_dept;
+--------+-------------+------+-----+---------+-------+
| Field | Type    | Null | Key | Default | Extra |
+--------+-------------+------+-----+---------+-------+
| deptno | int(11)   | YES |   | NULL  |    |
| dname | varchar(20) | YES |   | NULL  |    |
| loc  | varchar(40) | YES |   | NULL  |    |
| descri | int(11)   | YES |   | NULL  |    |
| id   | int(11)   | YES |   | NULL  |    |
+--------+-------------+------+-----+---------+-------+
5 rows in set (0.00 sec)

您可能感興趣的文章:

MySQL學(xué)習(xí)筆記3：表的基本操作介紹
mysql表的清空、刪除和修改操作詳解
MySQL修改表結(jié)構(gòu)操作命令總結(jié)
MySQL操作數(shù)據(jù)庫和表的常用命令新手教程
MySQL之終端Terminal（dos界面）管理數(shù)據(jù)庫、數(shù)據(jù)表、數(shù)據(jù)的基本操作
MySQL創(chuàng)建和刪除表操作命令實(shí)例講解
MySQL中復(fù)制數(shù)據(jù)表中的數(shù)據(jù)到新表中的操作教程

標(biāo)簽：定西浙江中衛(wèi) 南寧鄂州阿里上海張家界

巨人網(wǎng)絡(luò)通訊聲明：本文標(biāo)題《mysql學(xué)習(xí)筆記之表的基本操作》，本文關(guān)鍵詞 mysql,學(xué)習(xí),筆記,之表,的,；如發(fā)現(xiàn)本文內(nèi)容存在版權(quán)問題，煩請?zhí)峁┫嚓P(guān)信息告之我們，我們將及時(shí)溝通與處理。本站內(nèi)容系統(tǒng)采集于網(wǎng)絡(luò)，涉及言論、版權(quán)與本站無關(guān)。