search
HomeDatabaseMysql Tutorialpaip.hibernatelist返回位null的解决

paip.hibernate list 返回位null的解决 但是size是对的... 里面都是null... hb3.2版本...oracle11g =========原因:没主键 也许没主键,看累挂,真的没... 走加上...在myeclipse生成...走ok兰...发现生成的pojo和没主键的时候儿也不一样... 作者 老哇

paip.hibernate list 返回位null的解决
但是size是对的...

里面都是null...

hb3.2版本...oracle11g
=========原因:没主键

也许没主键,看累挂,真的没...
走加上...在myeclipse生成...走ok兰...发现生成的pojo和没主键的时候儿也不一样...
作者 老哇的爪子 Attilax 艾龙, EMAIL:1466519819@qq.com
来源: http://blog.csdn.net/attilax
// Fields

private Long id;
private Long vdnid;
private Long userid;
private Long confkbstypepid;
private Long departmentid;
private Long grpsubsitepid;
private String question;
private String keyword;
private String answer;
private Long belong;


// Property accessors
@GenericGenerator(name = "generator", strategy = "increment")
@Id
@GeneratedValue(generator = "generator")
@Column(name = "ID", unique = true, nullable = false, precision = 22, scale = 0)
public Long getId() {
return this.id;
}


要是没主键,走弄个..
// Fields

private TConfKbsId id;

// Property accessors
@EmbeddedId
@AttributeOverrides( {
@AttributeOverride(name = "vdnid", column = @Column(name = "VDNID", precision = 22, scale = 0)),
@AttributeOverride(name = "userid", column = @Column(name = "USERID", precision = 22, scale = 0)),
@AttributeOverride(name = "confkbstypepid", column = @Column(name = "CONFKBSTYPEPID", precision = 22, scale = 0)),
@AttributeOverride(name = "departmentid", column = @Column(name = "DEPARTMENTID", precision = 22, scale = 0)),
@AttributeOverride(name = "grpsubsitepid", column = @Column(name = "GRPSUBSITEPID", precision = 22, scale = 0)),
@AttributeOverride(name = "id", column = @Column(name = "ID", precision = 22, scale = 0)),
@AttributeOverride(name = "question", column = @Column(name = "QUESTION", length = 2048)),
@AttributeOverride(name = "keyword", column = @Column(name = "KEYWORD", length = 2048)),
@AttributeOverride(name = "answer", column = @Column(name = "ANSWER", length = 1096)),
@AttributeOverride(name = "belong", column = @Column(name = "BELONG", precision = 22, scale = 0)) })
public TConfKbsId getId() {
return this.id;
}

参考

hibernate 查询视图返回list为null的解决方法 2013-01-08 16:12:37

分类: Linux

hibernate查询视图时,会将视图的所有字段作为主键,如果存在为空字段则返回值就为空,也就查询不到相应的结果。myeclipse反转工具生成的实体包含两个表,一个表是EntPriWarQueryId,一个表是EntPriWarQuery,处理方法如下:
1.把此表EntPriWarQuery当做普通的表处理,增加主键及主键生成策略,还有相关的get和set方法,也就是说把该表处理成普通的实体;
2.在创建视图时把可能为空的字段做处理,forexampl:
case when p.fileno is null then '0'
else p.fileno
end as fileno,
是为空的字段有值即可;
Statement
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Explain the InnoDB Buffer Pool and its importance for performance.Explain the InnoDB Buffer Pool and its importance for performance.Apr 19, 2025 am 12:24 AM

InnoDBBufferPool reduces disk I/O by caching data and indexing pages, improving database performance. Its working principle includes: 1. Data reading: Read data from BufferPool; 2. Data writing: After modifying the data, write to BufferPool and refresh it to disk regularly; 3. Cache management: Use the LRU algorithm to manage cache pages; 4. Reading mechanism: Load adjacent data pages in advance. By sizing the BufferPool and using multiple instances, database performance can be optimized.

MySQL vs. Other Programming Languages: A ComparisonMySQL vs. Other Programming Languages: A ComparisonApr 19, 2025 am 12:22 AM

Compared with other programming languages, MySQL is mainly used to store and manage data, while other languages ​​such as Python, Java, and C are used for logical processing and application development. MySQL is known for its high performance, scalability and cross-platform support, suitable for data management needs, while other languages ​​have advantages in their respective fields such as data analytics, enterprise applications, and system programming.

Learning MySQL: A Step-by-Step Guide for New UsersLearning MySQL: A Step-by-Step Guide for New UsersApr 19, 2025 am 12:19 AM

MySQL is worth learning because it is a powerful open source database management system suitable for data storage, management and analysis. 1) MySQL is a relational database that uses SQL to operate data and is suitable for structured data management. 2) The SQL language is the key to interacting with MySQL and supports CRUD operations. 3) The working principle of MySQL includes client/server architecture, storage engine and query optimizer. 4) Basic usage includes creating databases and tables, and advanced usage involves joining tables using JOIN. 5) Common errors include syntax errors and permission issues, and debugging skills include checking syntax and using EXPLAIN commands. 6) Performance optimization involves the use of indexes, optimization of SQL statements and regular maintenance of databases.

MySQL: Essential Skills for Beginners to MasterMySQL: Essential Skills for Beginners to MasterApr 18, 2025 am 12:24 AM

MySQL is suitable for beginners to learn database skills. 1. Install MySQL server and client tools. 2. Understand basic SQL queries, such as SELECT. 3. Master data operations: create tables, insert, update, and delete data. 4. Learn advanced skills: subquery and window functions. 5. Debugging and optimization: Check syntax, use indexes, avoid SELECT*, and use LIMIT.

MySQL: Structured Data and Relational DatabasesMySQL: Structured Data and Relational DatabasesApr 18, 2025 am 12:22 AM

MySQL efficiently manages structured data through table structure and SQL query, and implements inter-table relationships through foreign keys. 1. Define the data format and type when creating a table. 2. Use foreign keys to establish relationships between tables. 3. Improve performance through indexing and query optimization. 4. Regularly backup and monitor databases to ensure data security and performance optimization.

MySQL: Key Features and Capabilities ExplainedMySQL: Key Features and Capabilities ExplainedApr 18, 2025 am 12:17 AM

MySQL is an open source relational database management system that is widely used in Web development. Its key features include: 1. Supports multiple storage engines, such as InnoDB and MyISAM, suitable for different scenarios; 2. Provides master-slave replication functions to facilitate load balancing and data backup; 3. Improve query efficiency through query optimization and index use.

The Purpose of SQL: Interacting with MySQL DatabasesThe Purpose of SQL: Interacting with MySQL DatabasesApr 18, 2025 am 12:12 AM

SQL is used to interact with MySQL database to realize data addition, deletion, modification, inspection and database design. 1) SQL performs data operations through SELECT, INSERT, UPDATE, DELETE statements; 2) Use CREATE, ALTER, DROP statements for database design and management; 3) Complex queries and data analysis are implemented through SQL to improve business decision-making efficiency.

MySQL for Beginners: Getting Started with Database ManagementMySQL for Beginners: Getting Started with Database ManagementApr 18, 2025 am 12:10 AM

The basic operations of MySQL include creating databases, tables, and using SQL to perform CRUD operations on data. 1. Create a database: CREATEDATABASEmy_first_db; 2. Create a table: CREATETABLEbooks(idINTAUTO_INCREMENTPRIMARYKEY, titleVARCHAR(100)NOTNULL, authorVARCHAR(100)NOTNULL, published_yearINT); 3. Insert data: INSERTINTObooks(title, author, published_year)VA

See all articles

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

AI Hentai Generator

AI Hentai Generator

Generate AI Hentai for free.

Hot Tools

ZendStudio 13.5.1 Mac

ZendStudio 13.5.1 Mac

Powerful PHP integrated development environment

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

mPDF

mPDF

mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),

EditPlus Chinese cracked version

EditPlus Chinese cracked version

Small size, syntax highlighting, does not support code prompt function

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools