如果一个字段中没有指定DEFAULT修饰符,MySQL会依据这个字段是NULL还是NOT NULL自动设置默认值。如果指定字段可以为NULL,则MySQL为其设置默认值为NULL。如果是NOT NULL字段,MySQL对于数值类型插入0,字符串类型插入空字符串,时间戳类型插入当前日期和时间,ENUM类型插入枚举组的第一条。 NOT NULL DEFAULT '' 不能为null ...
【说站】mysql中default的使用 1、用于设置列的默认值,如果没有为某个字段赋值,系统会自动为该字段插入默认值。 没赋值指的是,当insert插入数据时,该字段没有指明。 2、如果指定空值,则存储的最终值是空值。 实例 代码语言:javascript 代码运行次数:0 mysql>create tableuser(ageint(11)default18);QueryOK,0row...
In MySQL 5.6 we changed the default query_cache_size to 1M, with query_cache_type to OFF. From a usability perspective, this made sense: having to enable two options together to work is confusing. pfs shows that the Query cache mutex is still acquired when the size is non-zero: https:...
If strict mode is not enabled, MySQL sets the column to the implicit default value for the column data type. In this case,ihas no explicit default, so in strict mode each of the following statements produce an error and no row is inserted. When not using strict mode, only the third st...
use default setting in SQL query, see in example below: --- -- Tables -- (MySQL format) --- CREATE TABLE Books ( ID INT(4) NOT NULL AUTO_INCREMENT, Title TEXT NOT NULL, Author TEXT NOT NULL, PRIMARY KEY (ID) ); CREATE TABLE Descriptions ( ...
deletefromdep whereid=2;# 删除dep表中的id为2的销售部门,emp表中对应dep销售部门的员工也跟着删除了mysql> deletefromdep whereid=2; Query OK,1row affected (0.23sec) mysql> select *fromdep; +---+---+---+ |id| name | comment | +---+---+---+ |1| IT | 搞技术 | |33| HR | ...
mysql> insert into t16(id,name) values(1,'cmz'); # sex没有传入,默认为male Query OK,1row affected (0.36sec) mysql>desc t16;+---+---+---+---+---+---+ | Field | Type | Null | Key | Default | Extra | +---+---+---+---+---+---+ | id |int(11) |...
default schema填写一个数据库名称（需已存在的）参考资料：http://bbs.17shares.com 默认库的意思，看你要登录那个库
large_query_threshold large_query_worker_percentage leak_mod_to_check lease_time location_cache_priority location_cache_cpu_quota location_cache_expire_time location_cache_refresh_min_interval location_cache_refresh_rpc_timeout location_cache_refresh_sql_timeout location_fetch_concurrency location_refresh...
MySQL Forums Forum List » General Advanced Search New Topic default JOINPosted by: samit jain Date: June 11, 2008 12:30PM Hi, Will this query do an INNER Join (or NATURAL Join) by default if I have keys on the join columns? select * from T1,T2 where T1.c1=T2.c1 or ...