mysqlAdvanced(六)Common Question Summary

MySQL View learning:

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When performing a delete operation, the following appears Error message:

The reason for the above problem is that operations involving primary and foreign keys in the database should be set to cascade deletion when deleting them. As shown in the figure below:

When deleting data in the view, the following error message appears:

Solution: To delete the data in the view, you should actually delete the data in the base table. Only in this way can the data in the view be deleted.

Note: In fact, this is only done when directly completing the SQL command or manually adding object information. Only the default value of the field value will take effect. It should be possible to implement it in Java code, but you need to do some tricks when executing the SQL statement.

中BLOBField type introduction:

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## The meaning of each character in

:

##MySQL

：select * from table name where condition 1 and condition 2 and condition 3