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法律MySQL 等價於 Sybase ASE 命令？
MySQL 等價於 sybase ASE 命令是 EXPLAIN 關鍵字。我們首先建立一個表 -
mysql> create table DemoTable1531 -> ( -> StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> StudentName varchar(20) -> ); Query OK, 0 rows affected (2.92 sec) mysql> create index Name_index1 on DemoTable1531(StudentName); Query OK, 0 rows affected (0.99 sec) Records: 0 Duplicates: 0 Warnings: 0
使用 insert 命令在表中插入一些記錄 -
mysql> insert into DemoTable1531(StudentName) values('Chris');
Query OK, 1 row affected (0.19 sec)
mysql> insert into DemoTable1531(StudentName) values('Robert');
Query OK, 1 row affected (0.10 sec)
mysql> insert into DemoTable1531(StudentName) values('David');
Query OK, 1 row affected (0.12 sec)
mysql> insert into DemoTable1531(StudentName) values('Mike');
Query OK, 1 row affected (0.12 sec)
mysql> insert into DemoTable1531(StudentName) values('Carol');
Query OK, 1 row affected (0.09 sec)使用 select 語句顯示錶中的所有記錄 -
mysql> select * from DemoTable1531;
這將產生以下輸出 -
+-----------+-------------+ | StudentId | StudentName | +-----------+-------------+ | 5 | Carol | | 1 | Chris | | 3 | David | | 4 | Mike | | 2 | Robert | +-----------+-------------+ 5 rows in set (0.00 sec)
以下是實現 MySQL 等價於 Sybase ASE 的查詢 -
mysql> EXPLAIN select * from DemoTable1531 where StudentName='Mike';
這將產生以下輸出 -
+----+-------------+---------------+------------+------+---------------+-------------+---------+-------+------+----------+-------------+ | id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra | +----+-------------+---------------+------------+------+---------------+-------------+---------+-------+------+----------+-------------+ | 1 | SIMPLE | DemoTable1531 | NULL | ref | Name_index1 | Name_index1 | 63 | const | 1 | 100.00 | Using index | +----+-------------+---------------+------------+------+---------------+-------------+---------+-------+------+----------+-------------+ 1 row in set, 1 warning (0.00 sec)
更新於： 12-12-2019
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