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這篇文章主要為大家展示了“MySQL 5.5如何刪除索引”,內(nèi)容簡而易懂,條理清晰,希望能夠幫助大家解決疑惑,下面讓小編帶領(lǐng)大家一起研究并學(xué)習(xí)一下“MySQL 5.5如何刪除索引”這篇文章吧。
mysql> show keys from dept2;
+-------+------------+-----------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+-------+------------+-----------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| dept2 | 0 | PRIMARY | 1 | deptno | A | 4 | NULL | NULL | | BTREE | | |
| dept2 | 1 | idx_dept2_deptno | 1 | deptno | A | 4 | NULL | NULL | | BTREE | | |
| dept2 | 1 | idx_dept2_report_date | 1 | report_date | A | 4 | NULL | NULL | YES | BTREE | | |
+-------+------------+-----------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
3 rows in set (0.00 sec)
方法①
mysql> drop index idx_dept2_deptno on dept2;
Query OK, 0 rows affected (0.02 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> show keys from dept2;
+-------+------------+-----------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+-------+------------+-----------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| dept2 | 0 | PRIMARY | 1 | deptno | A | 4 | NULL | NULL | | BTREE | | |
| dept2 | 1 | idx_dept2_report_date | 1 | report_date | A | 4 | NULL | NULL | YES | BTREE | | |
+-------+------------+-----------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
2 rows in set (0.00 sec)
--方法②
mysql> alter table dept2 drop index idx_dept2_report_date;
Query OK, 0 rows affected (0.05 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> show keys from dept2;
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| dept2 | 0 | PRIMARY | 1 | deptno | A | 4 | NULL | NULL | | BTREE | | |
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
1 row in set (0.00 sec)
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