本篇文章主要介绍了"企业如何给MYSQL创建表，查询表，创建索引实例"，主要涉及到方面的内容，对于其他数据库感兴趣的同学可以参考一下：
创建表数据类型 int（整形，整数） not null，char（字符） tinyint（最小的整形） varchar （变长的字符类型）create ta...
| Field | Type | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| name | char(20) | NO | MUL | NULL | |
| age | tinyint(2) | NO | | 0 | |
| dept | varchar(16) | YES | | NULL | |
+-------+-------------+------+-----+---------+----------------+
4 rows in set (0.00 sec)
指定前N个字符创建索引
mysql> create index index_dept on student(dept(8)); 创建 索引 索引名 在 表（第几个列（前几个字符））
Query OK, 0 rows affected (0.00 sec)
Records: 0 Duplicates: 0 Warnings: 0
查看索引 详细
mysql> show index from student\G;
*************************** 1. row ***************************
Table: student
Non_unique: 0
Key_name: PRIMARY
Seq_in_index: 1
Column_name: id
Collation: A
Cardinality: 0
Sub_part: NULL
Packed: NULL
Null:
Index_type: BTREE
Comment:
*************************** 2. row ***************************
Table: student
Non_unique: 1
Key_name: index_name
Seq_in_index: 1
Column_name: name
Collation: A
Cardinality: NULL
Sub_part: NULL
Packed: NULL
Null:
Index_type: BTREE
Comment:
*************************** 3. row ***************************
Table: student
Non_unique: 1
Key_name: index_x
Seq_in_index: 1
Column_name: age
Collation: A
Cardinality: NULL
Sub_part: NULL
Packed: NULL
Null:
Index_type: BTREE
Comment:
*************************** 4. row ***************************
Table: student
Non_unique: 1
Key_name: index_dept
Seq_in_index: 1
Column_name: dept
Collation: A
Cardinality: NULL
Sub_part: 8
Packed: NULL
Null: YES
Index_type: BTREE
Comment:
4 rows in set (0.00 sec)
联合索引语法
create index index_name_dept on student(name,dept);
Table: student
Non_unique: 1
Key_name: ind_name_dept
Seq_in_index: 2
Column_name: dept
Collation: A
Cardinality: NULL
Sub_part: NULL
Packed: NULL
Null: YES
Index_type: BTREE
Comment:
6 rows in set (0.00 sec)
mysql> drop index ind_name_dept on student; 删除索引 索引名 在 哪个表
Query OK, 0 rows affected (0.00 sec)
Records: 0 Duplicates: 0 Warnings: 0
创建联合索引前几个字符创建索引
create index ind_name_dept on student(name(8),dept(10));
到底给那些数据创建索引呢？
