( <FILESTREAM_option> ) | <HADR_options> | <mixed_page_allocation_option> | <parameterization_option> | <query_store_options> | <recovery_option> | <remote_data_archive_option> | <persistent_log_buffer_option> | <service_broker_option> | <snapshot_option> | <sql_option> | <suspend_...
( <FILESTREAM_option> ) | <HADR_options> | <mixed_page_allocation_option> | <parameterization_option> | <query_store_options> | <recovery_option> | <remote_data_archive_option> | <persistent_log_buffer_option> | <service_broker_option> | <snapshot_option> | <sql_option> | <...
或者可以用INSTR,FIND_IN_SET等函数,正好借此测试了下这个三个函数的效率。 建表: CREATE TABLE `fast_input` ( `id` int(11) NOT NULL AUTO_INCREMENT COMMENT '主键', `content` varchar(100) DEFAULT NULL COMMENT '内容', PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8; 循环插入数据 ...
#sql中的表 #创建表: CREATE TABLE employee( id INT PRIMARY KEY auto_increment , name VARCHAR (20), gender BIT default 1, birthday DATA , department VARCHAR (20), salary DECIMAL (8,2) unsigned, ); #sql中的表纪录 #添加一条表纪录: INSERT employee (name,gender,birthday,salary,department) ...
len()。 当你调用 len() 时,会执行 QuerySet。正如你所期望的,这将返回结果列表的长度。 注意:如果你只需要确定集合中的记录数(而不需要实际的对象),那么使用 SQL 的 SELECT COUNT(*) 在数据库层面上处理计数会更有效率。Django 提供了一个 count() 方法正是为了这个原因。 list()。 通过调用 list() 强...
4 rows in set (0.00 sec) mysql> rollback; Query OK, 0 rows affected (0.01 sec) mysql> 可以看到这两个语句确实都不会报错,且带 and 的 update 语句匹配到了具体的行(Rows matched: 1),但是没有修改数据(Changed: 0),标准语法下的 update 语句倒是正常修改了数据。
There is an IMO big caveat of bulk_create(): It does not set primary key of objects it creates. In my current project, using bulk_create would improve performance, but as I often need an id of the newly created objects, I have to save them one by one. ...
-> PRIMARY KEY(ID) -> )ENGINE=InnoDB CHARACTER SET ‘utf8’ COLLATE ‘utf8_general_ci’; Query OK, 0 rows affected (0.01 sec) 我们可以发现对于字段类型写成BOOL或者BOOLEAN,MySQL的SQL语法都是允许通过的,另外我们再通过SHOW命令查阅创建好的表结构: ...
SqlQuery(String, Object[]) Creates a raw SQL query that will return entities in this set. By default, the entities returned are tracked by the context; this can be changed by calling AsNoTracking on theDbSqlQuery<TEntity>returned. Note that the entities returned are always of the type for ...
Here is the SQL to reproduce this: ``` CREATE TABLE `User` ( `id` INTEGER NOT NULL AUTO_INCREMENT, PRIMARY KEY (`id`) ) DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci; -- CreateTable CREATE TABLE `Post` ( `id` INTEGER NOT NULL AUTO_INCREMENT, ...