Classification and common database of database
Relational databases and non-relational databases
Relational: MySQL , the Oracle , sqlserver
Non-relational: Redis , etc.
A brief three relational database paradigm?
The first paradigm: the column can not be divided, ensuring atomicity of each column
The second paradigm: completely dependent on the primary key attribute
Third Pattern: attribute does not depend on other non-primary property
Four basic characteristics or a transaction ACID properties.
Atomicity, consistency, isolation, durability
Mysql default database maximum number of connections?
100
Talk about mysql paging? Oracle paging?
Mysql Limit paging,
Oracle using three nested query
Simple talk about the flip-flop usage scenarios database?
For example, the school network, happy network, Facebook , you send a log to automatically notify friends, in fact, increase the log after doing a trigger, again written notification table entry. Because of the high trigger efficiency.
Simple talk about using stored procedures scene database?
1. In general, complex business logic requires multiple SQL statements. These statements are to be sent from the client to the server, when operating between the client and server number, will generate a lot of network traffic. If these operations are stored in a process, then the network traffic between the client and the server would be greatly reduced, reducing the network load.
With jdbc how to call a stored procedure?
Load the driver
Get connected
Setting parameters
carried out
Release resources
Briefly about you jdbc understand?
Database connection technology, and the like may be CRUD operations on the database.
Write a simple jdbc program. Write a visit oracle data jdbc program?
Jia Lian For Deacons
Load the driver
Get connected
SQL statements
Implementation of sql statement
Release resources
JDBC in the PreparedStatement compared to the Statement of benefits:
1. preparedstatement precompiled, than statement fast
2. readability and maintainability of the code
preparedstatement prevents sql injection, while the statement is not.
Database connection pool role:
Prevent data connection is too large to cause a system crash situation occurs.