ibatis | 易学教程

SQL query for asp.net grid pagination

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问题 I am using iBatis and SQLServer , What is the best way for using offset and limit for pagging queries? Maybe I add the column ROW_NUMBER() OVER (ORDER BY Id) AS RowNum , but this will only prevent data access for simple queries. There is some cases that I use union of selects. How to optmize these queries? 回答1: I don't know anything about ibatis, but I guess you could do this in SQL. If I understand you correctly, you want to get paginate the results of a select statement or union of a few

Hibernate vs iBatis

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问题 We are building a fairly database centric web application. We initially started off using iBatis. At one point we thought iBatis may not be very useful for the following reasons: 1. Need for the appl. code to determine if we need to insert/update/delete from DB 2. Appl. code will deviate from being object oriented to being database oriented 3. Need to write a lot boiler plate code for many trivial things like entity versions(to avoid dirty DB updates) and many more... Now we are more than

ibatis inline parameter with # in order by clause

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问题 below is my ibatis map configuration, <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE sqlMap PUBLIC "-//ibatis.apache.org//DTD SQL Map 2.0//EN" "http://ibatis.apache.org/dtd/sql-map-2.dtd"> <sqlMap namespace="Contact">  <select id="getAll" resultClass="com.nik.Contact"> select * from contact <dynamic prepend="where "> salary like '%' <isNotNull property="orderby" > order by #orderby#, #orderby2# </isNotNull> </dynamic> </select> </sqlMap> this is my pojo

MyBatis - Nested Conditions in Where Clause

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问题 I'm dynamically generating the where clause inside MyBatis v3 mapper xml. However placing parentheses is really cumbersome. Is there an easier way to handle the problem without using if statements? <where> <if test="filter != null"> <choose> <when test="filter.lref != null"> file.lref = #{filter.lref} </when> <otherwise>  <if test="filter.forLike != null || filter.forInt != null"> ( </if> <if test="filter.forLike != null" > subject LIKE #{filter.forLike} OR

How can I reuse an SQL fragment with parameters?

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问题 I'm intending to make a fragment for reusing with parameters. <insert ...> <selectKey keyProperty="id" resultType="_long" order="BEFORE"> <choose> <when test="_databaseId == 'derby'"> VALUES NEXT VALUE FOR SOME_ID_SEQ </when> <otherwise> SELECT SOME_ID_SEQ.NEXTVAL FROM DUAL </otherwise> </choose> </selectKey> INSERT INTO ... </insert> Can I make an SQL fragment using parameters? <sql id="selectKeyFromSequence"> <selectKey keyProperty="id" resultType="_long" order="BEFORE"> <choose> <when test

PostgreSQL - integer[] best practice

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问题 Working on a web app lately I decided to use integer[] in the data model. Having 2 tables, one with articles' data and a second with tags (tag id and description), decided to the tag ids an article would be tagged with in a article.tags integer[] column. As Milen A. Radev pointed out: Tip: Arrays are not sets; searching for specific array elements can be a sign of database misdesign. Consider using a separate table with a row for each item that would be an array element. This will be easier

How to prevent concurrency issue in UPDATE via iBatis

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问题 Our Java EE web application performs database operations using iBatis (ORM). The database operation flow is as below Flow : JSP --->Action--->ServiceIMpl--->DaoImpl---->Calling update query thru' IBatis Note : The Action, Service & DAO classes are instantiated using Spring 2.5's Dependency Injection technique. We use Struts2. Problem : 2 concurrent users search for the same record and User1 updates Attribute1 while User2 updates Attribute2. User1 first clicks on 'Save' and then User2 clicks

Multiple statements in single mapper method in MyBatis

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问题 I have a mapper method to delete all records in a table. But first I need to delete all records from associated junction table. This is what I tried: @Delete("delete from COC_BLOCK_FIELD; delete from COC_BLOCK;") void deleteBlocks(); That seemed reasonable, yet MyBatis throws an exception when processing my mapper: Caused by: org.apache.ibatis.exceptions.PersistenceException: ### Error updating database. Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in

Calling Oracle stored procedures with MyBatis

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问题 I am in the process of moving our database over to Oracle from SQL Server 2008 but cannot get MyBatis to work. Given the following example: UserMapper.xml (example) <resultMap type="User" id="UserResult"> <id property="userId" column="userId"/> <result property="firstName" column="firstName"/> <result property="lastName" column="lastName"/> </resultMap> <select id="getUsers" statementType="CALLABLE" resultMap="UserResult"> {CALL GetUsers()} </select> UserDAO.java public interface UserDAO {

四、SSM三大框架整合之登录功能实现

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1、整合思路　　　　①、表现层，也就是 Controller,由 SpringMVC 来控制，而SpringMVC 是Spring 的一个模块，故不需要整合。　　②、业务层，也就是 service，通常由 Spring 来管理 service 接口，我们会使用 xml 配置的方式来将 service 接口配置到 spring 配置文件中。而且事务控制一般也是在 service 层进行配置。　　③、持久层，也就是 dao 层，而且包括实体类，由 MyBatis 来管理，通过 spring 来管理 mapper 接口，使用mapper的扫描器自动扫描mapper接口在spring中进行注册。　　很明显，spring 在三大框架的整合中占据至关重要的地位，类似于一个大管家，将 MyBatis 和 SpringMVC 揉合在一起。回到顶部 2、准备环境　　①、数据库环境　　　　数据库类型：MySQL 5.1 　　　　数据库名称：ssm 　　　　数据表：user 　　　　　　②、开发工具 eclipse 　　③、JDK 1.7 　　④、mybatis 3.3 　　⑤、SpringMVC 4.2.4 　　⑥、Spring 4.2.4 　　⑦、数据库连接池 dbcp1.2.2 　　⑧、数据库驱动包mysql5.1.26 　　⑨、日志 log4j 1.2 　　案例需求