table of Contents
Database of words:
| Vocab | Word description |
|---|---|
| innodb | Transaction, primary keys, foreign keys, tree, table row lock |
| myisam | Mainly inserted into a reader, and insert operations |
| memory | All data is stored in memory |
| ACID | Atomicity, consistency, isolation, durability |
| create，drop，alter | Table - CRUD |
| insert，delete，update，select | Data - CRUD |
| grant | Create a user command |
| identified | confirm password |
| int、tinyint | A small number |
| float、double | Decimal |
| datetime、date | date |
| char、varchar | char0-255, longer storage |
| unsigned | Unsigned, the positive into negative |
| default | Default defalut 666 |
| enmu,set： | Radio multiple choice |
| Table constraint: | |
| not null | Not be empty |
| not null unique | Primary key |
| unique | The only constraint |
| auto_increment | ID increment |
| primary key | Primary key |
| foreign key | 外键：foreign key(id) references biao(sid) |
| on delete cascade | Cascade delete |
| on update cascade | Cascade update |
| Single-table query: | |
| distinct | Deduplication: select distinct field from table |
| between | Range: back where between 100 and 200 |
| is in | Judging, in which whether the ancestral |
| like | Fuzzy query%, underscore |
| group by | Groups: group by post |
| count、max、min、avg、sum | Aggregate function |
| count、group by | + Polymerizable groups: on the front function from, the discharge groups |
| having | Screening is generally placed at the end face: having count (id)> 3 |
| order by desc、asc | Sort: odder by field desc |
| limit | Paging query, limiting the number of inquiries, on the last limit 5,6 |