Programmer Think

In recent days, I want to make a login interface with Jframe. When connecting to the database, I found that the getText() of JPasswordField is out of date and cannot be used. After checking the data, we found that it was changed to: try{ String sql="SELECT * FROM username WHERE name=?"; conn = DB.getConnectio ...

Oracle Active Data Guard and Automatic Block Repair Starting in Oracle Database 11g Release 2 (11.2), the primary database automatically attempts to repair the corrupted block in real time by fetching a good version of the same block from a physical standby database. This capability is referred to as automatic block repair, and it allows corrup ...

Affairs: Why do you want to open a transaction? In the program, it's not just compiled, but the same as the logical line. Transactions can help us to execute logic better Data source: Database connection optimization helps us link databases faster If the data source has a database pool, you can take it directly from the database pool import co ...

Written in front Mysql is a magical relational database. I really feel that it's awesome. Because the projects I've done are quite miscellaneous, I've met Oracle database before, which gives me the impression that Oracle is very cumbersome and cumbersome, with many configurations. If it's used for small projects, it's like killing chickens and ...

Mysql Management Operations Database management operations View database structure Create and delete libraries and tables Manage records for tables Basic Operational Commands View database list information SHOW DATABASES [root@localhost ~]# mysql -u root -p Enter password: Welcome to the MySQL monitor. Commands end with ; or \g. Your ...

java.sql.PreparedStatement(SQL preprocessing) Prevent SQL injection As long as your sql parameters are provided by users, you need to use sql preprocessing When setting parameters, you need to select the corresponding data type to set, otherwise there will be problems when processing the type One of the advantages of setObject is that you can j ...

The ABCR function of Oracle 11gr2 has been introduced. When a damaged database is retrieved, it will be automatically repaired. Now test whether the database will be automatically repaired when the database block is damaged and the instance is forced to close.First, test the general user table, baiyang.t'ou objs(I) current active and standby en ...

Summary Two pages in totalWhen accessing the product list directly, it will judge whether the user is logged in. If the user is not logged in, it will jump for 3 secondsIf the user logs in, there is no jumpLogin page: for login page, enter user name and password directly. Compare with database to loginAnd save the password locally ps usually ne ...

(1) case of ashes -- UDTF seeking wordcount Data format:Each line is a string and separated by spaces.Code implementation: object SparkSqlTest { def main(args: Array[String]): Unit = { //Block redundant logs Logger.getLogger("org.apache.hadoop").setLevel(Level.WARN) Logger.getLogger("org.apache.spark").setLevel(Leve ...

Download Spark on Spark official website Spark Download The version is free. After downloading, extract it and put it under bigdata (the directory can be changed) Download the file winutils.exe required by Hadoop under Windows Let's find it on the Internet. It won't be uploaded here. In fact, this file is optional, and error reporting doesn' ...