 **Primary index:**

A primary index is an index on a set of fields that includes
the unique primary key for the field and is guaranteed not to contain duplicates.
Also Called a **Clustered index**. 
eg. Employee ID can be Example of it. 


**Secondary index:**

A Secondary index is an index that is not a primary index and may have duplicates.
eg. Employee name can be example of it. Because Employee name can have similar values.

The primary index contains the key fields of the table. The primary index is automatically created in the database when the table is activated. If a large table is frequently accessed such that it is not possible to apply primary index sorting, you should create secondary indexes for the table.

The indexes on a table have a three-character index ID. &#39;0&#39; is reserved for the primary index. Customers can create their own indexes on SAP tables; their IDs must begin with Y or Z.

I am using `docker run /bin/bash` to develop my container and every time I want to use `Ctrl+p` in a terminal or in emacs, I have to type it twice, since docker uses it to detach from a container (`Ctrl+p` `Ctrl+q`).

How can I change `Ctrl+p` to something else more convenient that is not used in emacs or in a terminal setting?

docker change Ctrl+p to something else?

I have this line in `.iss` file:

    Source: &quot;..\Tcl\*&quot;; DestDir: &quot;{app}\Tcl&quot;; Flags: ignoreversion

which packs folder `Tcl`. But it takes only files inside folder, but does not take subfolders inside `Tcl`. Is there a way to take entire folder `Tcl` with all subfolders and files? (without listing all that subfolders line by line).

Inno Setup 5.4.2.


Inno Setup: pack folder with all subfolders

Can any one tell me what&#39;s the exact difference between Primary index &amp; Secondary index?
What are the different indexes that comes under category of primary &amp; secondary index?
And what&#39;s advantages of using primary index over secondary index &amp; vice versa?

What is difference between primary index and secondary index exactly?

<p>Can any one tell me what's the exact difference between Primary index &#x26; Secondary index?
What are the different indexes that comes under category of primary &#x26; secondary index?
And what's advantages of using primary index over secondary index &#x26; vice versa?</p>


Re,

I have the following query:

    $property = 
        Property::select(
            DB::raw(&quot;title, lat, lng, ( 
                3959 * acos( 
                    cos( radians(:lat) ) * 
                    cos( radians( lat ) ) * 
                    cos( radians( lng ) - radians(:lng) ) + 
                    sin( radians(:lat) ) * 
                    sin( radians( lat ) ) 
                ) 
            ) AS distance&quot;, [&quot;lat&quot; =&gt; $lat, &quot;lng&quot; =&gt; $lng, &quot;lat&quot; =&gt; $lat])
        )
        -&gt;having(&quot;distance&quot;, &quot;&lt;&quot;, $radius)
        -&gt;orderBy(&quot;distance&quot;)
        -&gt;take(20)
        -&gt;get();

It doesn&#39;t work: ```Invalid parameter number: mixed named and positional parameters ```.

Does anyone know a trick or a workaround (I can obviously write the full query but prefer to use fluent builder).

How to bind parameters to a raw DB query in Laravel that&#39;s used on a model?

In Laravel, if I perform a query:

    $foods = Food::where(...)-&gt;get();

...then `$foods` is an [Illuminate Collection](http://laravel.com/api/4.2/Illuminate/Database/Eloquent/Collection.html) of `Food` model objects.  (Essentially an array of models.)

However, the keys of this array are simply:

    [0, 1, 2, 3, ...]

...so if I want to alter, say, the `Food` object with an `id` of 24, I can&#39;t do this:

    $desired_object = $foods-&gt;get(24);
    $desired_object-&gt;color = &#39;Green&#39;;
    $desired_object-&gt;save();

...because this will merely alter the 25th element in the array, not the element with an `id` of 24.

**How do I get a single (or multiple) element(s) from a collection by ANY attribute/column (such as, but not limited to, id / color / age / etc.)?**

Of course, I can do this:

    foreach ($foods as $food) {
    	if ($food-&gt;id == 24) {
    		$desired_object = $food;
            break;
    	}
    }
    $desired_object-&gt;color = &#39;Green&#39;;
    $desired_object-&gt;save();

...but, that&#39;s just gross.

And, of course, I can do this:

    $desired_object = Food::find(24);
    $desired_object-&gt;color = &#39;Green&#39;;
    $desired_object-&gt;save();

...but that&#39;s *even more gross*, because it performs an additional unnecessary query when I already have the desired object in the `$foods` collection.

Thanks in advance for any guidance.

EDIT:

To be clear, you *can* call `-&gt;find()` on an Illuminate Collection without spawning another query, but it *only* accepts a primary ID.  For instance:

    $foods = Food::all();
    $desired_food = $foods-&gt;find(21);  // Grab the food with an ID of 21

However, there is still no clean (non-looping, non-querying) way to grab an element(s) by an attribute from a Collection, like this:

    $foods = Food::all();
    $green_foods = $foods-&gt;where(&#39;color&#39;, &#39;green&#39;); // This won&#39;t work.  :(

Laravel: Get Object From Collection By Attribute

I&#39;m getting an error saying that the table type doesn&#39;t support FULLTEXT indices. How can I achieve this?

Here&#39;s my table:

    CREATE TABLE gamemech_chat (
      id bigint(20) unsigned NOT NULL auto_increment,
      from_userid varchar(50) NOT NULL default &#39;0&#39;,
      to_userid varchar(50) NOT NULL default &#39;0&#39;,
      text text NOT NULL,
      systemtext text NOT NULL,
      timestamp datetime NOT NULL default &#39;0000-00-00 00:00:00&#39;,
      chatroom bigint(20) NOT NULL default &#39;0&#39;,
      PRIMARY KEY  (id),
      KEY from_userid (from_userid),
      FULLTEXT KEY from_userid_2 (from_userid),
      KEY chatroom (chatroom),
      KEY timestamp (timestamp)
    )  ;

*

#1214 - The used table type doesn&#39;t support FULLTEXT indexes

This sql code throws an 

 &gt; aggregate functions are not allowed in WHERE

    SELECT o.ID ,  count(p.CAT)
    FROM Orders o
    INNER JOIN Products p ON o.P_ID = p.P_ID 
    WHERE count(p.CAT) &gt; 3
    GROUP BY o.ID;

How can I avoid this error?


How to avoid error &quot;aggregate functions are not allowed in WHERE&quot;

I have the following entry in my DB table

    eventName(varchar 100) -&gt; myEvent
    date(timestamp) -&gt; 2013-03-26 09:00:00

and I am trying to use the following query;

    SELECT * 
    FROM eventList 
    WHERE `date` BETWEEN UNIX_TIMESTAMP(1364256001) AND UNIX_TIMESTAMP(1364342399)

i.e between 2013-03-26 00:00:01 and 2013-03-26 23:59:59

but it is giving me 0 results.

I have tried expanding the date range with no luck and there are definitely results within the range.

any help is appreciated.

MYSQL query between two timestamps

I have two separate databases. I am trying to update a column in one database to the values of a column from the other database:


    UPDATE customer
    SET customer_id=
       (SELECT t1 FROM dblink(&#39;port=5432, dbname=SERVER1 user=postgres password=309245&#39;,
       &#39;SELECT store_key FROM store&#39;) AS (t1 integer));

This is the error I am receiving:

&gt;     ERROR:  more than one row returned by a subquery used as an expression


Any ideas?

Postgres Error: More than one row returned by a subquery used as an expression

I&#39;m currently using the below code to insert data in a table:

&lt;!-- language: php --&gt;

    &lt;?php
    
    public function saveDetailsCompany()
    {
        $post = Input::All();
    
        $data = new Company;
        $data-&gt;nombre = $post[&#39;name&#39;];
        $data-&gt;direccion = $post[&#39;address&#39;];
        $data-&gt;telefono = $post[&#39;phone&#39;];
        $data-&gt;email = $post[&#39;email&#39;];
        $data-&gt;giro = $post[&#39;type&#39;];
        $data-&gt;fecha_registro = date(&quot;Y-m-d H:i:s&quot;);
        $data-&gt;fecha_modificacion = date(&quot;Y-m-d H:i:s&quot;);
    
        if ($data-&gt;save()) {
            return Response::json(array(&#39;success&#39; =&gt; true), 200);
        }
    }

I want to return the last ID inserted but I don&#39;t know how to get it.

Kind regards!

Get the Last Inserted Id Using Laravel Eloquent

I&#39;m close to having my project ready to launch. I have big plans for after launch and the database structure is going to change -- new columns in existing tables as well as new tables, and new associations to existing and new models.

I haven&#39;t touched migrations in Sequelize yet, since I&#39;ve only had testing data which I don&#39;t mind wiping out every time the database changes.

To that end, at present I&#39;m running `sync force: true` when my app starts up, if I have changed the model definitions. This deletes all the tables and makes them from scratch. I could omit the `force` option to have it only create new tables. But if existing ones have changed this is not useful.

So once I add in migrations how do things work? Obviously I don&#39;t want existing tables (with data in them) to be wiped out, so `sync force: true` is out of the question. On other apps I&#39;ve helped develop (Laravel and other frameworks) as part of the app&#39;s deployment procedure we run the migrate command to run any pending migrations. But in these apps the very first migration has a skeleton database, with the database in the state where it was some time early in development -- the first alpha release or whatever. So even an instance of the app late to the party can get up to speed in one go, by running all migrations in sequence.

How do I generate such a &quot;first migration&quot; in Sequelize? If I don&#39;t have one, a new instance of the app some way down the line will either have no skeleton database to run the migrations on, or it will run sync at the start and will make the database in the new state with all the new tables etc, but then when it tries to run the migrations they won&#39;t make sense, since they were written with the original database and each successive iteration in mind.

My thought process: at every stage, the initial database plus each migration in sequence should equal (plus or minus data) the database generated when `sync force: true` is run. This is because the model descriptions in the code describe the database structure. So maybe if there is no migration table we just run sync and mark all the migrations as done, even though they weren&#39;t run. Is this what I need to do (how?), or is Sequelize supposed to do this itself, or am I barking up the wrong tree? And if I&#39;m in the right area, surely there should be a nice way to auto generate most of a migration, given the old models (by commit hash? or even could each migration be tied to a commit? I concede I am thinking in a non-portable git-centric universe) and the new models. It can diff the structure and generate the commands needed to transform the database from old to new, and back, and then the developer can go in and make any necessary tweaks (deleting/transitioning particular data etc).

When I run the sequelize binary with the `--init` command it gives me an empty migrations directory. When I then run `sequelize --migrate` it makes me a SequelizeMeta table with nothing in it, no other tables. Obviously not, because that binary doesn&#39;t know how to bootstrap my app and load the models.

I must be missing something.

TLDR: how do I set up my app and its migrations so various instances of the live app can be brought up to date, as well as a brand new app with no legacy starting database?

Sequelize.js: how to use migrations and sync

I have an Asp.Net MVC 5 website with EntityFramework codefirst approach in a shared hosting plan. It uses the open source [WebbsitePanel](http://www.websitepanel.net/) for control panel and its SQL Server panel is somewhat limited. Today when I wanted to edit the database, I encountered this error:

    The transaction log for database &#39;db_name&#39; is full due to &#39;LOG_BACKUP&#39;

I searched around and found a lot of related answers like [this](https://stackoverflow.com/questions/8025344/transaction-log-for-database-is-full-sql-error) and [this](https://stackoverflow.com/questions/13975905/potential-causes-and-solutions-for-the-transaction-log-in-database-being-full) or [this](https://stackoverflow.com/questions/56628/how-do-you-clear-the-sql-server-transaction-log) but the problem is they suggest running a query on the database. I tried running 

    db.Database.ExecuteSqlCommand(&quot;ALTER DATABASE db_name SET RECOVERY SIMPLE;&quot;);

with the visual studio (on the `HomeController`) but I get the following error:

    System.Data.SqlClient.SqlException: ALTER DATABASE statement not allowed within multi-statement transaction.

How can I solve my problem? Should I contact the support team (which is a little poor for my host) or can I solve this myself?



&quot;The transaction log for database is full due to &#39;LOG_BACKUP&#39;&quot; in a shared host

I&#39;m intrigued in the database service Datomic, but I&#39;m not sure if it fits the needs of the projects I work on. When is Datomic a good choice, and when should it be avoided?

When should I use Datomic?

I was writing some tasks yesterday and it struck me that I don&#39;t really know **THE PROPER and ACCEPTED way** of checking if row exists in table when I&#39;m using  PL/SQL. 

For examples sake let&#39;s use table: 

    PERSON (ID, Name); 

Obviously I **can&#39;t do** (unless there&#39;s some secret method) something like:

    BEGIN 
      IF EXISTS SELECT id FROM person WHERE ID = 10; 
        -- do things when exists
      ELSE
        -- do things when doesn&#39;t exist
      END IF;
    END;
So my standard way of solving it was:

    DECLARE
      tmp NUMBER;
    BEGIN 
      SELECT id INTO tmp FROM person WHERE id = 10; 
      --do things when record exists
    EXCEPTION
      WHEN no_data_found THEN
      --do things when record doesn&#39;t exist
    END; 

However I don&#39;t know if it&#39;s accepted way of doing it, or if there&#39;s any better way of checking, I would really apprieciate if someone could share their wisdom with me. 

Proper way of checking if row exists in table in PL/SQL block

I would like to get the DATETIME column from an Oracle DB Table with JDBC. Here is my code:

    int columnType = rsmd.getColumnType(i);
    if(columnType == Types.DATE)
    {
        Date aDate = rs.getDate(i);
        valueToInsert = aDate.toString();
    }
    else if(columnType == Types.TIMESTAMP)
    {
        Timestamp aTimeStamp = rs.getTimestamp(i);
    	valueToInsert = aTimeStamp.toString();
    }
    else
    {
    	valueToInsert = rs.getString(i);
    }

I have to identify the column type first. The field I am interested in is recognized as a Types.DATE, but it is really a DATETIME in the DB since it has this format: &quot;07.05.2009 13:49:32&quot;

getDate truncates the time: &quot;07.05.2009&quot;
and getString appends &quot;.0&quot; to it: &quot;07.05.2009 13:49:32.0&quot;

Of course I could just remove the final .0 and work with getString all the time, but it is a dirty workaround.

Any ideas? I was looking for a getDateTime method.




JDBC ResultSet: I need a getDateTime, but there is only getDate and getTimeStamp

I have been pretty much fascinated by these two data types. According to **[Oracle Docs][1]**, they are presented as follows :

**BLOB :** Variable-length binary large object string that can be up to 2GB (2,147,483,647) long. Primarily intended to hold non-traditional data, such as voice or mixed media. BLOB strings are not associated with a character set, as with FOR BIT DATA strings.

**CLOB :** Variable-length character large object string that can be up to 2GB (2,147,483,647) long. A CLOB can store single-byte character strings or multibyte, character-based data. A CLOB is considered a character string.

What I don&#39;t know, is whether there is any difference between the two from DB2 and Oracle perspective? I mean, what are the differences between DB2 CLOB and Oracle CLOB, also between DB2 BLOB and Oracle BLOB? What is the maximum size of both in DB2 and Oracle? Is it just 2 GB ?

  [1]: http://docs.oracle.com/cd/E35137_01/doc.32/e18460/oracle_db2_compared.htm

Difference between CLOB and BLOB from DB2 and Oracle Perspective?

I&#39;m getting this error:

&gt; ORA-01950: no privileges on tablespace &#39;USERS&#39;

I have a default tablespace and I&#39;m able to create tables, however, they do not show at the objects tab in Toad.
I cannot insert anything into tables I create.

ORA-01950: no privileges on tablespace &#39;USERS&#39;

Is there any command that I can run so that I can get all the sequences? 
I am using Oracle 11g. I am using Toad for Oracle to connect to it. I can visually see the sequences in Toad, but I like to know the command line for it.

How can I get all sequences in an Oracle database?

I am trying to save a csv to a folder after making some edits to the file. 

Every time I use `pd.to_csv(&#39;C:/Path of file.csv&#39;)` the csv file has a separate column of indexes. I want to avoid printing the index to csv.

I tried: 

    pd.read_csv(&#39;C:/Path to file to edit.csv&#39;, index_col = False)

And to save the file...

    pd.to_csv(&#39;C:/Path to save edited file.csv&#39;, index_col = False)

However, I still got the unwanted index column. How can I avoid this when I save my files?

How to avoid Python/Pandas creating an index in a saved csv?

What&#39;s the shortest way to get first item of `OrderedDict` in Python 3?

My best:

    list(ordered_dict.items())[0]

Quite long and ugly.

I can think of: 

    next(iter(ordered_dict.items()))       # Fixed, thanks Ashwini

But it&#39;s not very self-describing. 

Any better suggestions?

Shortest way to get first item of `OrderedDict` in Python 3

I need to convert a Google Spreadsheet column index into its corresponding letter value, for example, given a spreadsheet:

![enter image description here][1]

I need to do this (this function obviously does not exist, it&#39;s an example):

    getColumnLetterByIndex(4);  // this should return &quot;D&quot;
    getColumnLetterByIndex(1);  // this should return &quot;A&quot;
    getColumnLetterByIndex(6);  // this should return &quot;F&quot;

Now, I don&#39;t recall exactly if the index starts from `0` or from `1`, anyway the concept should be clear.

I didn&#39;t find anything about this on gas documentation.. am I blind? Any idea?

Thank you


  [1]: http://i.stack.imgur.com/DyaPs.png

Convert column index into corresponding column letter

I&#39;m curious about these two secondary indexes and differences between them. It is hard to imagine how this looks like. And I think, this will help more people than just me.

Difference between local and global indexes in DynamoDB

I&#39;m having some problems creating a foreign key to an existing table in a mysql database.

I have the table `exp`:

    +-------------+------------------+------+-----+---------+-------+
    | Field       | Type             | Null | Key | Default | Extra |
    +-------------+------------------+------+-----+---------+-------+
    | EID         | varchar(45)      | NO   | PRI | NULL    |       |
    | Comment     | text             | YES  |     | NULL    |       |
    | Initials    | varchar(255)     | NO   |     | NULL    |       |
    | ExpDate     | date             | NO   |     | NULL    |       |
    | InsertDate  | date             | NO   |     | NULL    |       |
    | inserted_by | int(11) unsigned | YES  | MUL | NULL    |       |
    +-------------+------------------+------+-----+---------+-------+

and I wan&#39;t to create a new table called `sample_df` referencing this, using the following:

    CREATE TABLE sample_df (
    df_id mediumint(5) unsigned AUTO_INCREMENT primary key,
    sample_type mediumint(5) unsigned NOT NULL,
    df_10 BOOLEAN NOT NULL,
    df_100 BOOLEAN NOT NULL,
    df_1000 BOOLEAN NOT NULL,
    df_above_1000 BOOLEAN NOT NULL,
    target INT(11) unsigned NOT NULL,
    assay MEDIUMINT(5) unsigned zerofill NOT NULL,
    insert_date TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
    inserted_by INT(11) unsigned NOT NULL,
    initials varchar(255),
    experiment VARCHAR(45),
    CONSTRAINT FOREIGN KEY (inserted_by) REFERENCES user (iduser),
    CONSTRAINT FOREIGN KEY (target) REFERENCES protein (PID),
    CONSTRAINT FOREIGN KEY (sample_type) REFERENCES sample_type (ID),
    CONSTRAINT FOREIGN KEY (assay) REFERENCES assays (AID),
    CONSTRAINT FOREIGN KEY (experiment) REFERENCES exp (EID)
    );

But I get the error:

    ERROR 1215 (HY000): Cannot add foreign key constraint

To get some more information I did:

    SHOW ENGINE INNODB STATUS\G

From which I got:

    FOREIGN KEY (experiment) REFERENCES exp (EID)
    ):
    Cannot find an index in the referenced table where the
    referenced columns appear as the first columns, or column types
    in the table and the referenced table do not match for constraint.


To me the column types seem to match, since they are both varchar(45).(I also tried setting the `experiment` column to not null, but this didn&#39;t fix it) So I guess the problem must be that `Cannot find an index in the referenced table where the referenced columns appear as the first columns`. But I&#39;m not quite sure what this means, or how to check/fix it. Does anyone have any suggestions? And what is meant by `first columns`?

Content Type	Original Author	Original Content on Stackoverflow
Question	user3099630	View Question on Stackoverflow
Solution 1 - Mysql	Kumod Singh	View Answer on Stackoverflow

What is difference between primary index and secondary index exactly?

Mysql Problem Overview

Mysql Solutions

Solution 1 - Mysql

Inno Setup: pack folder with all subfolders

docker change Ctrl+p to something else?

Attributions