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What do Clustered and Non clustered index actually mean?
... all the columns. You do not have to go first to the index and then to the table.
Writing to a table with a clustered index can be slower, if there is a need to rearrange the data.
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When to use “ON UPDATE CASCADE”
... ON UPDATE CASCADE would allow you to change the primary key value and any tables that have foreign key references to the value will be changed accordingly.
In reference to #4, if you change the child ID to something that doesn't exist in the parent table (and you have referential integrity), you s...
Alter a MySQL column to be AUTO_INCREMENT
I’m trying to modify a table to make its primary key column AUTO_INCREMENT after the fact. I have tried the following SQL, but got a syntax error notification.
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MySQL一次主从数据不一致的问题解决过程 - 数据库(内核) - 清泛网 - 专注C/...
...从服务器数据一致性的核对与修复 简单描述下过程
用pt-table-checksum校验数据一致性 描述工具原理
用pt-table-sync修复不一致的数据 描述了工具原理
操作过程
只把过程和用到的东西解释了下，有些参数选项等还需要查阅文档...
In SQL, what's the difference between count(column) and count(*)?
...column) does not
[edit] added this code so that people can run it
create table #bla(id int,id2 int)
insert #bla values(null,null)
insert #bla values(1,null)
insert #bla values(null,1)
insert #bla values(1,null)
insert #bla values(null,1)
insert #bla values(1,null)
insert #bla values(null,null)
se...
How do I temporarily disable triggers in PostgreSQL?
...ly, if you are wanting to disable all triggers, not just those on the USER table, you can use:
SET session_replication_role = replica;
This disables triggers for the current session.
To re-enable for the same session:
SET session_replication_role = DEFAULT;
Source: http://koo.fi/blog/2013/01...
Why do you create a View in a database?
...ews can hide complexity
If you have a query that requires joining several tables, or has complex logic or calculations, you can code all that logic into a view, then select from the view just like you would a table.
2. Views can be used as a security mechanism
A view can select certain columns an...
What are best practices for multi-language database design? [closed]
...hat is the best way to create multi-language database? To create localized table for every table is making design and querying complex, in other case to add column for each language is simple but not dynamic, please help me to understand what is the best choose for enterprise applications
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How to use index in select statement?
Lets say in the employee table, I have created an index(idx_name) on the emp_name column of the table.
8 Answers
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SQL statement to get column type
Is there a SQL statement that can return the type of a column in a table?
22 Answers
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