Their feature sets are not at all the same. Sqlite is an embedded database which has no network capabilities (unless you add them). So you can&#39;t use it on a network.

If you need

* Network access - for example accessing from another machine; 
* Any real degree of concurrency - for example, if you think you are likely to want to run several queries at once, or run a workload that has lots of selects and a few updates, and want them to go smoothly etc.
* a lot of memory usage, for example, to buffer parts of your 1Tb database in your 32G of memory.

You need to use mysql or some other server-based RDBMS.

Note that MySQL is not the only choice and there are plenty of others which might be better for new applications (for example pgSQL).

Sqlite is a very, very nice piece of software, but it has never made claims to do any of these things that RDBMS servers do. It&#39;s a small library which runs SQL on local files (using locking to ensure that multiple processes don&#39;t screw the file up). It&#39;s really well tested and I like it a lot.

Also, if you aren&#39;t able to choose this correctly by yourself, you probably need to hire someone on your team who can.

The sqlite team published an article explaining [when to use sqlite][1] that is great read. Basically, you want to avoid using sqlite when you have a lot of write concurrency or need to scale to terabytes of data. In many other cases, sqlite is a surprisingly good alternative to a &quot;traditional&quot; database such as MySQL.


  [1]: http://www.sqlite.org/whentouse.html

SQLite out-of-the-box is not really feature-full regarding concurrency. You will get into trouble if you have hundreds of web requests hitting the same SQLite database.

You should definitely go with MySQL or PostgreSQL.

If it is for a single-person project, SQLite will be easier to setup though.

My few cents to previous excellent replies.
the site www.sqlite.org works on a sqlite database. Here is the [link][1] when the author (Richard Hipp) replies to a similar question.


  [1]: http://www.mail-archive.com/sqlite-users@sqlite.org/msg00461.html

Often I need to check if some value is blank and write that &quot;No data present&quot; like that:

    @user.address.blank? ? &quot;We don&#39;t know user&#39;s address&quot; : @user.address

And when we have got about 20-30 fields that we need to process this way it becomes ugly.

What I&#39;ve made is extended String class with `or` method

    class String
      def or(what)
        self.strip.blank? ? what : self
      end
    end

    @user.address.or(&quot;We don&#39;t know user&#39;s address&quot;)

Now it is looking better. But it is still raw and rough

How it would be better to solve my problem. Maybe it would be better to extend `ActiveSupport class` or use helper method or mixins or anything else. What ruby idealogy, your experience and best practices can tell to me.

If string is empty then return some default value

After studying this page:

http://docs.python.org/distutils/builtdist.html

I am hoping to find some setup.py files to study so as to make my own (with the goal of making a fedora rpm file).

Could the s.o. community point me towards some good examples?

setup.py examples?

Any good rules of thumb on how to decide which of the two to use?

And, if you take over an Sqlite database, and the system is expected to &quot;get much larger&quot;, how to decide whether to stick with it or move to MySql?

Sqlite or MySql? How to decide?

<p>Any good rules of thumb on how to decide which of the two to use?</p>
<p>And, if you take over an Sqlite database, and the system is expected to "get much larger", how to decide whether to stick with it or move to MySql?</p>


i would like to do a find and replace inside an entire database not just a table.

How can i alter the script below to work?

     update [table_name] set [field_name] = replace([field_name],&#39;[string_to_find]&#39;,&#39;[string_to_replace]&#39;);

Do i just use an asterix?

     update * set [field_name] = replace([field_name],&#39;[string_to_find]&#39;,&#39;[string_to_replace]&#39;);

Find and replace entire mysql database

I have a few questions in regards to upgrading the RDS instance.

1. What is the downtime when upgrading the instance from let&#39;s say small to large. Is the downtime relatively similar when you go and change any instance type(small, large, xlarge) or are there determining factors such as database size that alter the timing.
2. Can anyone share a technique of how to upgrade the instance type avoiding the downtime using RDS? Is that even possible in RDS. It doesn&#39;t have to be in great detail just some cliff-notes/big-picture stuff.
3. Is there down time when you allocate more disk space?

AWS RDS instance upgrade down time

I can&#39;t quite get a grasp of MySQL&#39;s DECIMAL. I need the row to be able to contain a number anywhere from 00.0001 to 99.9999. How would I structure it to work like so?

How to use MySQL DECIMAL?

I have two tables: `groups` and `group_members`.

The `groups` table contains all the information for each group, such as its ID, title, description, etc.  

In the `group_members` table, it lists all the members who are apart of each group like this:

    group_id | user_id
    1 | 100
    2 | 23
    2 | 100
    9 | 601

Basically, I want to list THREE groups on a page, and I only want to list groups which have MORE than four members.  Inside the `&lt;?php while ?&gt;` loop, I then want to four members who are apart of that group. I&#39;m having no trouble listing the groups, and listing the members in another internal loop, I just cannot refine the groups so that ONLY those with more than 4 members show.

Does anybody know how to do this? I&#39;m sure it&#39;s with MySQL joins.



MySQL joins and COUNT(*) from another table

I want to have one table with two `TIMESTAMP` columns. One column to keep track of when the record was created and another to keep track of when it was modified. I want these values handled by the database. I don&#39;t want my app layer to have to think about it.

I know that if you have a `TIMESTAMP` column with a `DEFAULT CURRENT_TIMESTAMP` or an `ON UPDATE CURRENT_TIMESTAMP` you cannot have another `TIMESTAMP` column. You can use `DATETIME` but there is no way to default it, that I know of, outside of a trigger.

I found that you &lt;a href=&quot;https://web.archive.org/web/20160401143159/http://michaelkimsal.com/blog/mysql-using-two-timestamps-for-createdupdated-values/&quot;&gt;can have multiple `TIMESTAMP` columns&lt;/a&gt; by leaving each without `DEFAULT` or `ON UPDATE` and inserting `NULL` when the record is created, causing each to have the current timestamp. From that point on the first column will automatically be updated.

This works fantastically but it leaves me with a funny feeling. Like this may be a bug and it could be patched at any time. If this is the way it is supposed to work then so be it. I will merrily go on my way. Can anyone tell me if this is the best way to do this or should I be using triggers?

One Mysql Table with Multiple TIMESTAMP Columns

I am creating a system which polls devices for data on varying metrics such as CPU utilisation, disk utilisation, temperature etc. at (probably) 5 minute intervals using SNMP. The ultimate goal is to provide visualisations to a user of the system in the form of time-series graphs.

I have looked at using RRDTool in the past, but rejected it as storing the captured data indefinitely is important to my project, and I want higher level and more flexible access to the captured data. So my question is really:

*What is better, a relational database (such as MySQL or PostgreSQL) or a non-relational or NoSQL database (such as MongoDB or Redis) with regard to performance when querying data for graphing.*

## Relational

Given a relational database, I would use a `data_instances` table, in which would be stored every instance of data captured for every metric being measured for all devices, with the following fields:

Fields: `id` `fk_to_device` `fk_to_metric` `metric_value` `timestamp`

When I want to draw a graph for a particular metric on a particular device, I must query this singular table *filtering out* the other devices, and the other metrics being analysed for this device:

    SELECT metric_value, timestamp FROM data_instances
        WHERE fk_to_device=1 AND fk_to_metric=2

The number of rows in this table would be:

    d * m_d * f * t

where `d` is the number of **devices**, `m_d` is the accumulative **number of metrics** being recorded for all devices, `f` is the **frequency** at which data is polled for and `t` is the total amount of **time** the system has been collecting data.

For a user recording 10 metrics for 3 devices every 5 minutes for a year, we would have just under **5 million** records. 

### Indexes

Without indexes on `fk_to_device` and `fk_to_metric` scanning this continuously expanding table would take too much time. So indexing the aforementioned fields and also `timestamp` (for creating graphs with localised periods) is a requirement.

## Non-Relational (NoSQL)

MongoDB has the concept of a *collection*, unlike tables these can be created programmatically without setup. With these I could partition the storage of data for each device, or even each metric recorded for each device.

I have no experience with NoSQL and do not know if they provide any query performance enhancing features such as indexing, however the previous paragraph proposes doing most of the traditional relational query work in the structure by which the data is stored under NoSQL.

## Undecided

Would a relational solution with correct indexing reduce to a crawl within the year? Or does the collection based structure of NoSQL approaches (which matches my mental model of the stored data) provide a noticeable benefit?

Storing time-series data, relational or non?

I am studying for an undergraduate databases course.

I&#39;d like to know if there are any online sites that allow me to do queries against an already built and populated database (with a known schema), so I didn&#39;t have to install SQL and populate it with data myself.

I am currently doing some exercises by hand on a workbook I have here, but I&#39;m a bit afraid that I might be doing them wrong and it&#39;s hard to check their correctness without testing them against the &quot;real thing&quot;.

Thanks

(In our course we are using Oracle)

Online databases for trying out Oracle SQL queries?

What command should I use to create a MongoDB dump of my database?

How do I create a MongoDB dump of my database?

So, I&#39;m sure I&#39;m missing something simple here, but when I run mongo as a daemon (using mongod --fork or just mongod), I see different database content than if I just run &quot;mongo&quot; on the host machine.

My only assumption is that the data is being stored somewhere other than /data/db when it&#39;s running just the shell, and switches to /data/db when I boot the mongod. In that case, how do I get at my data when running mongod?

Mongodb - Difference between running &quot;mongo&quot; and &quot;mongod&quot; databases

I&#39;m interested in choosing an embedded DB engine for my WPF app. I would like information on how SQLite and latest SQL CE 4.0 compare. And if I should choose one over the other. Points of interest would be ORM support with EF4&#39;s CTP &amp; NHibernate 3.

Thanks in advance!

SQL Server Compact 4.0 vs. SQLite

I have a table layout that I want to populate with the result from a database query. I use a select all and the query returns four rows of data. 

I use this code to populate the TextViews inside the table rows.

```java
Cursor c = null;
c = dh.getAlternative2();
startManagingCursor(c);
// the desired columns to be bound
String[] columns = new String[] {DataHelper.KEY_ALT};
// the XML defined views which the data will be bound to
int[] to = new int[] { R.id.name_entry};

SimpleCursorAdapter mAdapter = new SimpleCursorAdapter(this, 
		 R.layout.list_example_entry, c, columns, to);
this.setListAdapter(mAdapter);
```

I want to be able to separate the four different values of KEY_ALT, and choose where they go. I want them to populate four different TextViews instead of one in my example above.

How can I iterate through the resulting cursor?

Iterate through rows from Sqlite-query

I&#39;m constructing a query using SQLAlchemy and SQLite3 in which I&#39;d like to select rows in which a String column contains a particular substring. What is the best way to accomplish this?  

SQLAlchemy query where a column contains a substring

### Background

I have an Android project that has a database with two tables: `tbl_question` and `tbl_alternative`.

To populate the views with questions and alternatives I am using cursors. There are no problems in getting the data I need until I try to join the two tables. 


&lt;pre&gt;
    Tbl_question  
    -------------
    _id  
    question  
    categoryid  
&lt;/pre&gt;

&lt;pre&gt;
    Tbl_alternative
    ---------------
    _id 
    questionid 
    categoryid 
    alternative
&lt;/pre&gt; 

I want something like the following:

    SELECT tbl_question.question, tbl_alternative.alternative where 
    categoryid=tbl_alternative.categoryid AND tbl_question._id = 
    tbl_alternative.questionid.` 

This is my attempt: 

    public Cursor getAlternative(long categoryid) {
                String[] columns = new String[] { KEY_Q_ID, KEY_IMAGE, KEY_QUESTION, KEY_ALT, KEY_QID};
                 String whereClause = KEY_CATEGORYID + &quot;=&quot; + categoryid +&quot; AND &quot;+ KEY_Q_ID +&quot;=&quot;+ KEY_QID;
                 Cursor cursor = mDb.query(true, DBTABLE_QUESTION + &quot; INNER JOIN &quot;+ DBTABLE_ALTERNATIVE, columns, whereClause, null, null, null, null, null);
                 if (cursor != null) {
                      cursor.moveToFirst();
                 }
                 return cursor;

I find this way to form queries harder than regular SQL, but have gotten the advice to use this way since it is less error prone. 

### Question

How do I join two SQLite tables in my application?


How do I join two SQLite tables in my Android application?

Why this query doesn&#39;t work? :( I tried to replace nested IF statement &quot;...SET lkey = IF(lkey &gt;= 11, lkey - 5, IF(lkey &gt; 5, lkey + 2,lkey))&quot;


    UPDATE pages
    SET lkey = CASE lkey WHEN lkey &gt;= 11 THEN
    		lkey - 5
    	ELSE
    		CASE lkey WHEN lkey &gt; 5 THEN
    			lkey + 2
    		ELSE
    			lkey
    		END
    	END,
    	rkey = CASE lkey WHEN lkey &gt;= 11 THEN
    		rkey - 5
    	ELSE
    		CASE rkey WHEN rkey &lt; 11 THEN
    			rkey + 2
    		ELSE
    			rkey
    		END
    	END
    WHERE rkey &gt; 5 AND
    	lkey &lt; 12;



Content Type	Original Author	Original Content on Stackoverflow
Question	Mawg says reinstate Monica	View Question on Stackoverflow
Solution 1 - Mysql	MarkR	View Answer on Stackoverflow
Solution 2 - Mysql	Josue	View Answer on Stackoverflow
Solution 3 - Mysql	Jerome WAGNER	View Answer on Stackoverflow
Solution 4 - Mysql	Maksee	View Answer on Stackoverflow

Sqlite or MySql? How to decide?

Mysql Problem Overview

Mysql Solutions

Solution 1 - Mysql

Solution 2 - Mysql

Solution 3 - Mysql

Solution 4 - Mysql

setup.py examples?

If string is empty then return some default value

Attributions