如何增强我的选择查询以使其在 MySQL 中运行得更快?
mysqlmysqli database
为了更快地进行查询，请使用 MySQL IN()，因为它在内部使用索引。让我们首先创建一个表 −
mysql> create table DemoTable1618 -> ( -> ClientId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> ClientName varchar(20), -> ClientEmailId varchar(30) -> ); Query OK, 0 rows affected (1.53 sec)
使用 insert 在表中插入一些记录 command:
mysql> insert into DemoTable1618(ClientName,ClientEmailId) values('Chris Brown','Brown323@gmail.com');
Query OK, 1 row affected (0.15 sec)
mysql> insert into DemoTable1618(ClientName,ClientEmailId) values('David Miller','MillerDavid@gmail.com');
Query OK, 1 row affected (0.16 sec)
mysql> insert into DemoTable1618(ClientName,ClientEmailId) values('John Doe','998John_Doe@gmail.com');
Query OK, 1 row affected (0.28 sec)
mysql> insert into DemoTable1618(ClientName,ClientEmailId) values('John Smith','999John_Smith@gmail.com');
Query OK, 1 row affected (0.16 sec)
mysql> insert into DemoTable1618(ClientName,ClientEmailId) values('Adam Smith','Adam_Smith@gmail.com');
Query OK, 1 row affected (0.17 sec)
使用 select 语句显示表中的所有记录 −
mysql> select * from DemoTable1618;
这将产生以下输出 −
+----------+--------------+-------------------------+ | ClientId | ClientName | ClientEmailId | +----------+--------------+-------------------------+ | 1 | Chris Brown | Brown323@gmail.com | | 2 | David Miller | MillerDavid@gmail.com | | 3 | John Doe | 998John_Doe@gmail.com | | 4 | John Smith | 999John_Smith@gmail.com | | 5 | Adam Smith | Adam_Smith@gmail.com | +----------+--------------+-------------------------+ 5 rows in set (0.00 sec)
以下是使用 IN() 进行更快查询的查询 −
mysql> select * from DemoTable1618 where ClientEmailId IN('998John_Doe@gmail.com','999John_Smith@gmail.com','MillerDavid@gmail.com');
这将产生以下输出 −
+----------+--------------+-------------------------+ | ClientId | ClientName | ClientEmailId | +----------+--------------+-------------------------+ | 2 | David Miller | MillerDavid@gmail.com | | 3 | John Doe | 998John_Doe@gmail.com | | 4 | John Smith | 999John_Smith@gmail.com | +----------+--------------+-------------------------+ 3 rows in set (0.00 sec)
