thread_cache_size:保存当前没有与连接关联但是准备为后面新的连接服务的线程,可以快速响应连接的线程请求而无需创建新的 table_cache:类似于thread_cache_size,但用来缓存表文件,对InnoDB效果不大,主要用于MyISAM 升级硬件 Scale up,这个不多说了,根据MySQL是CPU密集型还是I/O密集型,通过提升CPU和内存、使用SSD,都...
ALTER TABLE [ IF EXISTS ] name DETACH PARTITION partition_name 其中action 是以下之一: ADD [ COLUMN ] [ IF NOT EXISTS ] column_name data_type [ COLLATE collation ] [ column_constraint [ ... ] ] DROP [ COLUMN ] [ IF EXISTS ] column_name [ RESTRICT | CASCADE ] ALTER [ COLUMN ] co...
Bug #68040 ALTER TABLE ADD COLUMN TIMESTAMP DEFAULT CURRENT_TIMESTAMP still inserts zero Submitted: 6 Jan 2013 2:08Modified: 1 Mar 2013 16:51 Reporter: Elena Stepanova Email Updates: Status: Closed Impact on me: None Category: MySQL Server: DDLSeverity: S3 (Non-critical) Version: 5.6....
CREATE TABLE `111111` ( `id` int(11) DEFAULT NULL, ) ENGINE=InnoDB DEFAULT CHARSET=utf8 INSERT ... alter table `test`.`111111` add column `ts` timestamp DEFAULT current_timestamp NOT NULL after `id`; SELECT * ... data: id ts --- --- 1 0000-00-00 00:00:00 2 0000-00-00...
table 是要更改的表的名称。如果表不在当前数据库中或者不属于当前用户所拥有,可以显式指定数据库和所有者。 ALTER COLUMN 指定要更改给定列。如果兼容级别是 65 或小于 65,将不允许使用 ALTER COLUMN。 要更改的列不能是: 数据类型为 text、image、ntext 或 timestamp 的列。
Add Time in SQL HH:MM:SS to another HH:MM:SS Adding a column to a large (100 million rows) table with default constraint adding a extra column in a pivot table created uisng T-SQL Pivot Table query Adding a partition scheme to an existing table. Adding a Value to a 'date' Column...
假设需要在Customer客户表中增加一列LogoutTime,数据类型为TIMESTAMP(6),表示最后客户退出登录的时间,可以使用如下()方式。(第三章) ALTER TABLE CUSTOMER ADD COLUMN "LOGOUTTIME" TIMESTAMP(6) ; UPDATE TABLE CUSTOMER ADD COLUMN "LOGOUTTIME" TIMESTAMP(6) ;...
ALTER TABLE `test11` ADD COLUMN ( `ucid` bigint(20) NOT NULL DEFAULT0COMMENT'线索ucid', `clue_type`int(11) NOT NULL DEFAULT'1'COMMENT'线索类型1招生 2招商', `work_type`int(11) NOT NULL DEFAULT0COMMENT'线索工种', `allottime` TIMESTAMP notnullDEFAULT CURRENT_TIMESTAMP COMMENT'分单时间...
ALTER TABLE t2 ADD COLUMN c2 INT REFERENCES t1; ALTER TABLE t2 ADD c3 INT CHECK (c3 > 1) DEFAULT 10 ADD c4 DECIMAL(5,2) NOT NULL; ALTER TABLE t2 ADD c5 TIMESTAMP DEFAULT CURRENT TIMESTAMP ADD COLUMN c6 CHAR(20) DEFAULT 'xyz' ADD c7 INT REFERENCES t3; ...
ALTER TABLE members ADD birth_date DATE NOT NULL; Code language: SQL (Structured Query Language) (sql) In this example, the birth_date column is a DATE column and it does not accept null. Suppose, you want to record the time at which a row is created and updated. To do so, you ne...