瞧一瞧迷一般的SQLDA
You can use the DESCRIBE statement to obtain host variable information for any SELECT statement that has been prepared (using PREPARE), and store that information into the SQL descriptor area (SQLDA).
When the DESCRIBE statement gets executed in your application, the database manager defines your host variables in an SQLDA. Once the host variables are defined in the SQLDA, you can use the FETCH statement to assign values to the host variables, using a cursor.
- Declaring the SQLDA structure in a dynamically executed SQL program
An SQLDA contains a
variable number of occurrences of SQLVAR entries, each of which contains
a set of fields that describe one column in a row of data. There are
two types of SQLVAR entries: base SQLVAR entries and secondary SQLVAR
entries. - Preparing a dynamically executed SQL statement using the minimum SQLDA structure
Use the information provided here as an example of how
to allocate the minimum SQLDA structure for a statement. - Allocating an SQLDA structure with sufficient SQLVAR entries for dynamically executed SQL statements
After you determine
the number of columns in the result table, you must allocate storage
for a second full-size SQLDA. The first SQLDA is used for input parameters
and the second full-size SQLDA is used for output parameters. - Describing a SELECT statement in a dynamically executed SQL program
After you allocate sufficient space for the second SQLDA
(in this example, calledfulsqlda), you must code
the application to describe the SELECT statement. - Acquiring storage to hold a row
Before the application can fetch a row of the result table
using an SQLDA structure, the application must first allocate storage
for the row. - Processing the cursor in a dynamically executed SQL program
After you allocate the
SQLDA structure, you can open the cursor associated with the SELECT
statement and fetch rows. - Allocating an SQLDA structure for a dynamically executed SQL program
Allocate an SQLDA structure for your application so that
you can use it to pass data to and from your application. - Transferring data in a dynamically executed SQL program using an SQLDA structure
You have greater flexibility
when you transfer data using an SQLDA instead of using lists of host
variables. For example, you can use an SQLDA to transfer data that
has no native host language equivalent, such as DECIMAL data in the
C language. - Processing interactive SQL statements in dynamically executed SQL programs
You can write an application
using dynamic SQL to process arbitrary SQL statements. For example,
if an application accepts SQL statements from a user, the application
must be able to issue the statements without any prior knowledge of
the statements. - Determination of statement type in dynamically executed SQL programs
When an SQL statement
is prepared, you can determine information concerning the type of
statement by examining the SQLDA structure. This information is placed
in the SQLDA structure either at statement preparation time with the
INTO clause, or by issuing a DESCRIBE statement against a previously
prepared statement. - Processing variable-list SELECT statements in dynamically executed SQL programs
A varying-list SELECT
statement is one in which the number and types of columns that are
to be returned are not known at precompilation time. - Saving SQL requests from end users
If the users of your application can issue SQL requests
from the application, you might want to save these requests.
瞧一瞧迷一般的SQLDA的更多相关文章
- 瞧一瞧,看一看呐,用MVC+EF快速弄出一个CRUD,一行代码都不用写,真的一行代码都不用写!!!!
瞧一瞧,看一看呐用MVC+EF快速弄出一个CRUD,一行代码都不用写,真的一行代码都不用写!!!! 现在要写的呢就是,用MVC和EF弄出一个CRUD四个页面和一个列表页面的一个快速DEMO,当然是在不 ...
- 【转载】网易极客战记官方攻略-地牢- 迷一般的 Kithmaze
关卡连接: https://codecombat.163.com/play/level/riddling-kithmaze 如果你第一次走上歧途,改变你的循环来找到出路. 简介: 敬请期待! 默认代码 ...
- 瞧一瞧!这儿实现了MongoDB的增量备份与还原(含部署代码)
一 需求描述 我们知道数据是公司的重要资产,业务的系统化.信息化就是数字化.数据高效的存储与查询是系统完善和优化的方向,而数据库的稳定性.可靠性是实现的基础.高可用和RPO(RecoveryPoint ...
- Win10一周年纪念版,瞧一瞧Linux子系统
Bash Bash是一个命令处理器,通常运行于文本窗口中,并能执行用户直接输入的命令.Bash还能从文件中读取命令,这样的文件称为脚本.和其他Unix shell 一样,它支持文件名替换(通配符匹配) ...
- 走进 AQS 瞧一瞧看一看
并发中有一块很重要的东西就是AQS.接下来一周的目标就是它. 看复杂源码时,一眼望过去,这是什么?不要慌,像剥洋葱一样,一层层剥开(哥,喜欢"扒开"这个词). 参考资源: http ...
- 2020最新的web前端体系和路线图,想学web前端又不知道从哪开始的快来瞧一瞧呀
web前端其实是相对于服务器语言是简单的,并且对于初学者是非常友好的,因为在前期学习能够看到很好的效果.但是他的路线 也就是学习体系不成熟,所以导致很多初学者不知道怎么学?下面我就讲讲web前端的体系 ...
- 瞧一瞧React Fiber
啥是React Fiber? React Fiber,简单来说就是一个从React v16开始引入的新协调引擎,用来实现Virtual DOM的增量渲染. 说人话:就是一种能让React视图更新过程变 ...
- 手写Spring AOP,快来瞧一瞧看一看撒!
目录 AOP分析 Advice实现 定义Advice接口 定义前置.后置.环绕和异常增强接口 Pointcut实现 定义PointCut接口 定义正则表达式的实现类:RegExpressionPoin ...
- Java 反编译工具哪家强?对比分析瞧一瞧
前言 Java 反编译,一听可能觉得高深莫测,其实反编译并不是什么特别高级的操作,Java 对于 Class 字节码文件的生成有着严格的要求,如果你非常熟悉 Java 虚拟机规范,了解 Class 字 ...
随机推荐
- PHP Socket实现websocket(一)基本函数介绍
WebSocket protocol 是HTML5一种新的协议.它实现了浏览器与服务器全双工通信(full-duplex). 一开始的握手需要借助HTTP请求完成. WebSocket是基于TCP来实 ...
- PHPCMS调用form类编辑器editor函数动态上传图片附件
http://w3note.com/web/49.html phpcms v9的系统类库有一个表单类,它封装了表单的一些组件,如编辑器.图片上传.时间选择器.模板选 择器等,更详细请参考form.cl ...
- Java Io 之拷贝文件性能比较
前面我们共讨论了拷贝文件有三种方式: 1. 第一种,一个字节一个字节的进行拷贝文件操作. 2. 第二种,使用字节数据批量的进行拷贝文件操作. 3. 第三种,使用带缓冲输入输出流来拷贝文件. 那么哪一种 ...
- PL/sql developer连接数据库的问题以及oracle数据库中文乱码的问题
今天第二次配置PL/sql developer,表示很蛋疼,昨天因为动了一个东西然后莫名其妙的就再也连接不了数据库,总是显示各种错误,我动的东西是因为中文会显示乱码,(因为我是用32位的PL/sql ...
- cocos2dx 3.7中 AppDelegate.h的class TestController;这种写法的具体意思不太明白,只能猜是类似于外部定义的东西。
cocos2dx 3.7中 AppDelegate.h的class TestController;这种写法的具体意思不太明白,只能猜是类似于外部定义的东西.
- Java读写文件通用格式
String path = "I:\\"; File file = new File(path + "user_id_pair.txt"); FileReade ...
- 9.3---魔术索引(CC150)
魔术索引1:此外下一次应该看看课本上的方法. public boolean findMagicIndex(int[] A, int n){ for(int i = 0; i < A.length ...
- js原生的url操作函数,及使用方法。(附:下边还有jquery对url里的中文解码函数)
js原生的url操作函数,完善的. /*****************************/ /* 动态修改url */ /*****************************/ var ...
- 解读Unity中的CG编写Shader系列二
转自 http://www.itnose.net/detail/6095974.html 上一篇文章的例子中我们可以看到顶点着色器的输出参数可以说是直接作为了片段着色器的形参传递过来,那么不由得一个问 ...
- 13.SpringMVC和Spring集成(一) && 14.SpringMVC和Spring集成(二)
1.概念 Spring是一个开源框架,Spring是于2003 年兴起的一个轻量级的Java 开发框架,Spring致力于J2EE应用的各层的解决方案,Spring是企业应用开发的“一站式”选择,并贯 ...