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Concept: The cursor is used to process the query result (ResultSet) of the select statement. Some people also think that cursors are query results Use steps and grammatical formats (non-scrolling cursors) 1. Declare cursors Declaration area: Cursor cursor name is select statement ...

Snap-up and second-kill are common scenarios. Interviewers often ask questions during interviews, such as how to achieve the snap-up second-kill in Taobao. Buying and killing in seconds is very simple, but there are some problems to be solved, mainly for two problems:1. Pressure on databases caused by high concurrency2. How to ...

I. Introduction Through dynamic SQL, we can compile complex SQL, but the previous examples are single-table queries. In actual development, of course, not all single-table queries. Many times we need to carry out related multi-table queries (some companies still try to use single-table queries for performance). The relationship between tables ...

# JDBC Introduction Foundation, Use Steps Recently, in reviewing the knowledge of JDBC, first write a review of the basis of JDBC. For the understanding of JDBC, the full name of JDBC is Java Database Connectvity, so it is not difficult to write out, that is, using the java language to operate the database. JDBC actually defines ...

Preface Data Lake Analytic DLA (hereinafter referred to as DLA) can help users directly query and analyze data stored on OSS and TableStore through standard SQL statements. For the same data, it is not only different in storage space, but also different in execution time when using DLA query. Generally speaking, when data of the same size is st ...

Author: Nobody Source: CSDN Original text: https://blog.csdn.net/h1025372645/article/details/89191301 JDBC Java DataBase Connectivity,java database connection, in order to reduce the difficulty of operating data, java provides jdbc, according to the characteristics of java object-oriented, many operations are encapsulated. JDBC ...

I. Mass insertion of data MyISAM table insertion optimization, insertion before closing index updates. alter table xxx DISABLE KEYS; -- Turn off index updates ... -- insert data alter table xxx ENABLE KEYS; Insertion optimization of InnoDB tables: 1) The imported data is arranged according to the p ...

At ORACLE10g and 11g versions, the default log archive path for ORACLE is the flash-back recovery area ($ORACLE_BASE/flash_recovery_area).ORACLE has a limitation on this path: it only has 2G of space by default, and it is not only the default path for archive logs, but also the default address for backup files and flash back lo ...

A orm database Flutter plugin. I posted an article earlier. Hand-in-Hand Teaching You Elegant Use of ORM Database in Flutter Project Many people also put forward some valuable suggestions on consulting and using, saying that they do not want to write lua, which is not elegant enough, but also increases the cost of learning. On reflection, it is ...

1. parameterType (input type) (1) Pass simple types (such as int, which we can use directly) public Student getStudentById(Integer studentId); <select id="getStudentById" parameterType="int" resultType="student"> select * from tblstudent where studentId = #{studentId} </select> (2) Passing pojo objects     p ...