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创建索引
创建表的时候创建索引
语法:
create table table_name [col_name data_type] [unique|fulltext|spatial] [index|key] [index_name] (col_name [length]) [asc|desc]
在已经存在的表上创建索引
1.alter table语法:
alter table table_name add [unique|fulltext|spatial] [index|key] [index_name] (col_name[length],...) [asc|desc]
2.create index语法:
create [unique|fulltext|spatial] index index_name on table_name (col_name[length],...) [asc|desc]
示例
这里,以创建空间索引类型为例说明
创建表的时候创建索引:
create table t7(g geometry not null, spatial index spatIdx(g)) engine=MyISAM;
在已经存在的表上创建索引:
创建表t7,在表t7的空间数据类型字段g上创建名称为spatIdx的空间索引,SQL语句如下:
create table t7(g geometry not null) engine=MyISAM;
创建索引:
alter table方式:
alter table t7 add spatial index spatIdx(g);
create index方式:
create spatial index spatIdx on t7(g);
查看索引
mysql> show index from t7 \G
*************************** 1. row ***************************
Table: t7
Non_unique: 1
Key_name: spatIdx
Seq_in_index: 1
Column_name: g
Collation: A
Cardinality: NULL
Sub_part: 32
Packed: NULL
Null:
Index_type: SPATIAL
Comment:
Index_comment:
1 row in set (0.00 sec)
删除索引
1.alter table语法:
alter table table_name drop index index_name;
2.drop index语法:
drop index index_name on table_name;