How to compare identical databases in the same table? (如何比对同一张表的相同数据库)
How to Compare Identical Databases in the Same Table?
Database comparison is a crucial and mandatory practice to ensure the quality and consistency of a database. Identical databases in the same table may require a comparison to balance the data and avoid any discrepancies. The comparison helps detect any changes made to the database and solve the issues found. This article will guide you on how to compare identical databases in the same table.
Step 1: Understand the Databases
Before comparing the identical databases, it is essential to understand the databases you are comparing. Understanding the table structure, data types, and data values are key components to compare identical databases. Ensure that the database design for both is the same or at least compatible to enable easy and meaningful comparison.
Step 2: Select the Data Comparison tool
Several data comparison tools are avlable for comparing identical databases, including:
1. WinMerge: it is a robust open-source tool that compares files and folders. It highlights changes in the database, and this enables you to identify discrepancies and better solve any issues found.
2. SQL Data Compare: this is a pd tool from RedGate that has proven reliable for comparing databases of all kinds, including identical ones. It runs a comparison script that detects differences in the databases and directs you on how to solve the disparities found.
3. SQL Server Data Tools (SSDT): it is a free tool that enables database comparisons between the databases in the same instance. It has features such as schema comparison and data comparison, among others.
Step 3: Preparing the Databases for Comparison
It is important to prepare the databases before you start comparing them. The following steps serve as a guide:
1. Ensure that both databases are similar or identical in design, structure, data types, and data values.
2. Make a copy or backup of the two identical databases before the comparison.
3. Set up the comparison tool and connect to the two databases in question (databases names and server host).
4. Specify which data tables to compare or choose the entire database.
Step 4: Compare the Identical Databases
After preparing the databases, proceed to compare them using the data comparison tool. The following steps serve as a guide:
1. Select the data comparison tool and launch it.
2. After launching the tool, select the option for identical databases and select the databases to compare.
3. The tool prompts you to verify the databases to compare. Ensure that you select the right databases, and then click the compare button.
4. Wt for the tool to compare the databases. It may take some time, depending on the size of the databases.
5. After the comparison, the tool gives you a report that highlights the differences between the databases.
Step 5: Solve the Discrepancies
After comparing the identical databases, the tool lists the differences found. The differences could be in the structure, data types, or values of the data. Here are the steps to solve the differences:
1. Review the differences found by the tool and identify the critical disparities.
2. For every difference, decide the best way to align and balance the data. It may involve either deleting or updating the data values, or adding new data.
3. Apply the necessary updates to achieve consistency between the two identical databases.
4. After making changes, run the comparison tool agn to confirm that both databases are identical.
Conclusion
Comparing identical databases can help identify and solve any discrepancies that may hinder the quality and consistency of a database. It is essential to understand the databases, select a reliable data comparison tool, prepare the databases, and compare the databases. Solving the differences found after the comparison leads to a ooth and effective database system.
相关问题拓展阅读：
vfp数据库两张相同结构的表如何进行数据比对！（在线等！）
可以用这样的方法 b1(xh,xm),b2(xh,xm)
use b1 in 1
use b2 in 2
do while !eof()
select 1
a=xh
select 2
locate for a=xh
if !found()
select 1
delete
skip
else
select 1
skip
endif
enddo
select b1
copy to c for deleted()
那困培么b1中以字段xh为区别的不同记录就答尺凯存在c表中了
可行
试过
你要按照什么字段来区别都可以
每个字段都区别一下清唤也成
如果有需要可以给你写一个通用的
任何两个表之间不同记录的筛选
先看你的数据库有多少个字节，如果字节总数少于255最方便。新建一个数据库ttt.dbf，就一个字段AA，字符型，宽度254。
打开你的数据库，输入命令
copy to temp sdf
use ttt
appe from temp sdf
修改temp库结构，增加字段recn(C型，10位，用来保存记录号)，sl（N型，宽度1，保存相同记录的条数），ctrl＋w退出表设计器
repl all recn with str(recn(),10),sl with 1
inde on AA to 123
total on AA to 123
use 123
数据库123就是没有重复记录的新表，里面的sl是记录有相同的重复数量，recn是相同的之一条迅空记录位于原表的记录号。
如果原来的表总宽度大于255，小于509，可以再增加一个字段AB，先按AA字段TOTAL，再按AB字段TOTAL，然后把这样形成的两个新表的记录号都到老表标出，标出的记录拷贝出来就是敬樱无完全相同记录的表了。
补充问题和这原理一样，如果a和b字段相同的话，可以用上面的办法整理出两个temp表，temp1和temp2。先把temp1的所有记录都加上删除标记，把把b中有不一样记录的恢复，余下的就是所需。
sele 2
use temp2
sele 1
use temp1
dele all
go top
do while !eof()
sele 2
loca for !aa=a.aa
if !eof()
sele 1
reca
endif
sele 1
skip
enddo
pack
这样temp1中的记录号代表的原a表的记录组成的新表就是询问者所需。亮昌丛
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