主键约束(primary key)相当于唯一约束+非空约束的组合 不允许出现重复,也不允许出现空值 每个表只允许出现一个主键约束,一般跟在字段名后 删除主键约束后,非空还存在:alter table 表名称 drop primary key; 唯一键(unique key)简称UK 同一个表中可以有很多个唯一约束 会默认创建一个唯一索引 也是直接跟在字段名...
常用于primary key 和 unique 索引的查询。 null:这种访问方式意味着MySql能在优化阶段分解查询语句,在执行阶段甚至用不着再访问表或者索引。例如,从一个索引列里选取最小值可以通过单独查找索引来完成,不需要再执行时访问表。 possible_keys 这一列显示了查询可以使用哪些索引,这是基于查询访问的列和使用的比较操作符...
mysql> CREATE TABLE `sales` ( -> `id` bigint(20) NOT NULL , -> `uid` varchar(40) NOT NULL, -> `sale_num` bigint DEFAULT NULL, -> INDEX (`id`), -> UNIQUE KEY `ind_uid` (`uid`) -> ); `id` bigint(20) NOT NULL , `uid` varchar(40) NOT NULL, `sale_num` bigint ...
High Level Architecture Deprecate the IGNORE syntax for ALTER TABLE in 5.6 and remove IGNORE support for ALTER TABLE in 5.7. From the manual: "IGNORE is a MySQL extension to standard SQL. It controls how ALTER TABLE works if there are duplicates on unique keys in the new table or if warni...
Bug description I have a relationship between to Models. They and linked through a id. Initial I had set up that ID to be unique but the logic changed so I removed it. However, it does not remove the unique index from the MySQL table and...
mysql.models com.azure.resourcemanager.mysql.fluent.models com.azure.resourcemanager.mysql com.azure.resourcemanager.network.fluent com.azure.resourcemanager.network.models com.azure.resourcemanager.network.fluent.models com.azure.resourcemanager.network com.azure.resourcemanager.postgresql.fluen...
client_key path The path to the client private key. aliases: ssl_key collation - Collation mode (sorting). This only applies to new table/databases and does not update existing ones, this is a limitation of MySQL. config_file path
mysql> alter table t add index key_for_first_name(name); Query OK, 0 rows affected (0.01 sec) mysql> alter table t add index key_for_first_name(name); ERROR 1061 (42000): Duplicate key name 'key_for_first_name' Using custom names with indexes is a good practice because they can ...
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mysql.models com.azure.resourcemanager.mysql.fluent.models com.azure.resourcemanager.mysql com.azure.resourcemanager.network.fluent com.azure.resourcemanager.network.models com.azure.resourcemanager.network.fluent.models com.azure.resourcemanager.network com.azure.resourcemanager.postgresql.fluent...