Data format char (6) occupy the position of the variable data, for a maximum of six,
Regardless of input data format varchar (6) a few data are accounted for 6,
2. The access table structure
Select * from table name,
Desc table name,
3. The composite primary key (primary key uniquely identify a record)
When the primary key data repeat, the primary key conflict:
A. replace old data with new data
Insert into table name values (lov) on duplicate key update field name=new value, the field name=new value, the field name=new value,... ; Not involving the use of the original data,
B. directly to cover the original data
The replace into the table name values (list of values),
4. The auto_increment automatic growth
Insert into tablename values (null, mathematics)
If set on student id from growth, the data for mathematical) (1,
CodePudding user response:
Now what the problem is, please?