Yes, it does.

However, if you have foreign key constraints such as RESTRICT that ensure referential integrity with other tables, you&#39;ll want to drop those keys prior to dropping or truncating a table.

Yes it would drop the index.  There&#39;s no reason to keep the index if the underlying table isn&#39;t there.  I suspect that the downward migration is just doing the opposite of the upward migration on a one-to-one basis.

It is unneccessary. Your DROP TABLE might however be prevented when the table is part of foreign key relationships and dropping your table would break the dependencies.

From first glance, it would appear I have two basic choices for storing [ZIP codes][1] in a database table:

 1. Text (probably most common), i.e. `char(5)` or `varchar(9)` to support +4 extension
 2. Numeric, i.e. 32-bit integer

Both would satisfy the requirements of the data, if we assume that there are no international concerns.  In the past we&#39;ve generally just gone the text route, but I was wondering if anyone does the opposite?  Just from brief comparison it looks like the integer method has two clear advantages:

 - It is, by means of its nature, automatically limited to numerics only (whereas without validation the text style could store letters and such which are not, to my knowledge, ever valid in a ZIP code).  This *doesn&#39;t* mean we could/would/should forgo validating user input as normal, though!
 - It takes less space, being 4 bytes (which should be plenty even for 9-digit ZIP codes) instead of 5 or 9 bytes.

Also, it seems like it wouldn&#39;t hurt display output much.  It is trivial to slap a `ToString()` on a numeric value, use simple string manipulation to insert a hyphen or space or whatever for the +4 extension, and use string formatting to restore leading zeroes.

Is there anything that would discourage using `int` as a datatype for US-only ZIP codes?

  [1]: http://en.wikipedia.org/wiki/ZIP_code

Is it a good idea to use an integer column for storing US ZIP codes in a database?

How can I get the byte array from some string which can contain numbers, letters and so on?
If you are familiar with Java, I am looking for the same functionality of the getBytes() method.

I tried a snippet like this one:

    for($i = 0; $i &lt; strlen($msg); $i++){
    	$data.=ord($msg[$i]);
            //or $data[]=ord($msg[$1]); 
    }

but without success, so any kind of help will be appreciated.

PS: Why do I need this at all!? Well, I need to send a byte array via fputs() to a server written in Java... 

String to byte array in php

It&#39;s not explicitly mentioned in the documentation (http://dev.mysql.com/doc/refman/6.0/en/drop-table.html).  I ask because I just saw a curious database migration in a Rails project where the developer was removing all the indexes before dropping the table, and that seemed unnecessary.


Does dropping a table in MySQL also drop the indexes?

<p>It's not explicitly mentioned in the documentation (<a href="http://dev.mysql.com/doc/refman/6.0/en/drop-table.html" target="_blank" rel="noopener noreferrer">http://dev.mysql.com/doc/refman/6.0/en/drop-table.html</a>).  I ask because I just saw a curious database migration in a Rails project where the developer was removing all the indexes before dropping the table, and that seemed unnecessary.</p>


I know you can ALTER the column order in MySQL with FIRST and AFTER, but why would you want to bother? Since good queries explicitly name columns when inserting data, is there really any reason to care what order your columns are in in the table? 

Is there any reason to worry about the column order in a table?

The &#39;id&#39; field of my table auto increases when I insert a row. I want to insert a row and then get that ID.

I would do it just as I said it, but is there a way I can do it without worrying about the time between inserting the row and getting the id?

I know I can query the database for the row that matches the information that was entered, but there is a high change there will be duplicates, with the only difference being the id.


PHP/MySQL insert row then get &#39;id&#39;

Is it possible to somehow get structure of MySQL database, or just some table with simple query?

Or is there another way, how can I do it?

How to get database structure in MySQL via query

I&#39;m trying to display a datetime from my MySQL database as an iso 8601 formated string with PHP but it&#39;s coming out wrong.

17 Oct 2008 is coming out as: 1969-12-31T18:33:28-06:00 which is clearly not correct (the year should be 2008 not 1969)

This is the code I&#39;m using:

    &lt;?= date(&quot;c&quot;, $post[3]) ?&gt;

`$post[3] is the datetime (CURRENT_TIMESTAMP)` from my MySQL database.

Any ideas what&#39;s going wrong?



How to display a date as iso 8601 format with PHP

Given an array of ids `$galleries = array(1,2,5)` I want to have a SQL query that uses the values of the array in its WHERE clause like:

&lt;!-- language: lang-sql --&gt;

    SELECT *
    FROM galleries
    WHERE id = /* values of array $galleries... eg. (1 || 2 || 5) */

How can I generate this query string to use with MySQL?



Passing an array to a query using a WHERE clause

I&#39;m trying to determine how to ***count*** the matching rows on a table using the EntityFramework.

The problem is that each row might have many megabytes of data (in a Binary field).  Of course the SQL would be something like this:

    SELECT COUNT(*) FROM [MyTable] WHERE [fkID] = &#39;1&#39;;

I could load all of the rows and *then* find the Count with:

    var owner = context.MyContainer.Where(t =&gt; t.ID == &#39;1&#39;);
    owner.MyTable.Load();
    var count = owner.MyTable.Count();

But that is grossly inefficient.  Is there a simpler way?


----
EDIT: Thanks, all.  I&#39;ve moved the DB from a private attached so I can run profiling; this helps but causes confusions I didn&#39;t expect.

And my real data is a bit deeper, I&#39;ll use **Trucks** carrying **Pallets** of **Cases** of **Items** -- and I don&#39;t want the **Truck** to leave unless there is at least one **Item** in it. 

My attempts are shown below.  The part I don&#39;t get is that CASE_2 never access the DB server (MSSQL).


    var truck = context.Truck.FirstOrDefault(t =&gt; (t.ID == truckID));
    if (truck == null)
        return &quot;Invalid Truck ID: &quot; + truckID;
    var dlist = from t in ve.Truck
        where t.ID == truckID
        select t.Driver;
    if (dlist.Count() == 0)
        return &quot;No Driver for this Truck&quot;;

    var plist = from t in ve.Truck where t.ID == truckID
        from r in t.Pallet select r;
    if (plist.Count() == 0)
        return &quot;No Pallets are in this Truck&quot;;
    #if CASE_1
    /// This works fine (using &#39;plist&#39;):
    var list1 = from r in plist
        from c in r.Case
        from i in c.Item
        select i;
    if (list1.Count() == 0)
        return &quot;No Items are in the Truck&quot;;
    #endif

    #if CASE_2
    /// This never executes any SQL on the server.
	var list2 = from r in truck.Pallet
            from c in r.Case
            from i in c.Item
            select i;
    bool ok = (list.Count() &gt; 0);
    if (!ok)
        return &quot;No Items are in the Truck&quot;;
    #endif

    #if CASE_3
    /// Forced loading also works, as stated in the OP...
	bool ok = false;
 	foreach (var pallet in truck.Pallet) {
        pallet.Case.Load();
        foreach (var kase in pallet.Case) {
            kase.Item.Load();
            var item = kase.Item.FirstOrDefault();
            if (item != null) {
                ok = true;
                break;
            }
        }
        if (ok) break;
    }
    if (!ok)
        return &quot;No Items are in the Truck&quot;;
    #endif


And the SQL resulting from CASE_1 is piped through **sp_executesql**, but:

    SELECT [Project1].[C1] AS [C1]
    FROM   ( SELECT cast(1 as bit) AS X ) AS [SingleRowTable1]
    LEFT OUTER JOIN  (SELECT 
        [GroupBy1].[A1] AS [C1]
        FROM ( SELECT 
            COUNT(cast(1 as bit)) AS [A1]
            FROM   [dbo].[PalletTruckMap] AS [Extent1]
            INNER JOIN [dbo].[PalletCaseMap] AS [Extent2] ON [Extent1].[PalletID] = [Extent2].[PalletID]
            INNER JOIN [dbo].[Item] AS [Extent3] ON [Extent2].[CaseID] = [Extent3].[CaseID]
            WHERE [Extent1].[TruckID] = &#39;....&#39;
        )  AS [GroupBy1] ) AS [Project1] ON 1 = 1


[*I don&#39;t really have Trucks, Drivers, Pallets, Cases or Items; as you can see from the SQL the Truck-Pallet and Pallet-Case relationships are many-to-many -- although I don&#39;t think that matters.  My real objects are intangibles and harder to describe, so I changed the names.*]





How to COUNT rows within EntityFramework without loading contents?

I was wondering if anyone can tell me if *[MongoDB][1]* or *[CouchDB][2]* are ready for a **production** environment.  

I&#39;m now looking at these storage solutions (I&#39;m favouring MongoDB at the moment), however these projects are quite young and so I foresee that I&#39;m going to have to work quite hard to convince my manager that we should adopt this new technology.

What I&#39;d like to know is:

 1. Who is using MongoDB or CouchDB today in a production environment?

 2. How are you using MongoDB/CouchDB?

 3. What problems (if any) did you come across when you adopted this new storage mechanism (and how did you overcome them)?

 4. How did you deal with any migration issues that you had to deal with?

 5. Do you have any good/bad experiences with either of these solutions that you&#39;d like to share?


  [1]: http://www.mongodb.org/display/DOCS/Home
  [2]: http://couchdb.apache.org/

MongoDB or CouchDB - fit for production?

What is the difference between `JOIN` and `UNION`? Can I have an example?



What is the difference between JOIN and UNION?

I&#39;m considering using SQLite as a production database for a site that would receive perhaps 20 simultaneous users, but with the potential for a peak that could be many multiples of that (since the site would be accessible on the open internet and there&#39;s always a possibility that someone will post a link somewhere that could drive many people to the site all at once). 

Is SQLite a possibility? 

I know it&#39;s not an ideal production scenario. I&#39;m only asking if this is within the realm of being a realistic possibility.


SQLite as a production database for a low-traffic site?

In this MySQL table definition:

    CREATE TABLE groups (
      ug_main_grp_id smallint NOT NULL default &#39;0&#39;,
      ug_uid smallint  default NULL,
      ug_grp_id smallint  default NULL,
      KEY (ug_main_grp_id)
    );

What does the `KEY` keyword mean? It&#39;s not a primary key, it&#39;s not a foreign key, so is it just an index? If so, what is so special about this type of index created with `KEY`?

What does the KEY keyword mean?

How do I get the last element of a list?



I would like to index a list with another list like this

    L = [&#39;a&#39;, &#39;b&#39;, &#39;c&#39;, &#39;d&#39;, &#39;e&#39;, &#39;f&#39;, &#39;g&#39;, &#39;h&#39;]
    Idx = [0, 3, 7]
    T = L[ Idx ]

and T should end up being a list containing [&#39;a&#39;, &#39;d&#39;, &#39;h&#39;].

Is there a better way than

    T = []
    for i in Idx:
        T.append(L[i])

    print T
    # Gives result [&#39;a&#39;, &#39;d&#39;, &#39;h&#39;]



In Python, how do I index a list with another list?

Do you need to explicitly create an index, or is it implicit when defining the primary key?  Is the answer the same for MyISAM and InnoDB?

Is the primary key automatically indexed in MySQL?

Can I add a UNIQUE constraint to a PostgreSQL table, after it&#39;s already created?

    Create Table: CREATE TABLE `fuinfo` (
      `fid` int(10) unsigned NOT NULL,
      `name` varchar(40) NOT NULL,
      `email` varchar(128) NOT NULL,
      UNIQUE KEY `email` (`email`),
      UNIQUE KEY `fid` (`fid`)
    ) ENGINE=MyISAM DEFAULT CHARSET=utf8



I want to drop the unique key on `email`,how?

How to drop unique in MySQL?

How to delete my tables who all have the prefix `myprefix_`?

Note: need to execute it in phpMyAdmin

SQL: deleting tables with prefix

How can I drop all user tables in oracle?

I have problem with constraints. When I disable all it is still no possible.

How to drop all user tables?

I&#39;m writing some migration scripts for an Oracle database, and was hoping Oracle had something similar to MySQL&#39;s &lt;code&gt;IF EXISTS&lt;/code&gt; construct.

Specifically, whenever I want to drop a table in MySQL, I do something like

    DROP TABLE IF EXISTS `table_name`;

This way, if the table doesn&#39;t exist, the &lt;code&gt;DROP&lt;/code&gt; doesn&#39;t produce an error, and the script can continue.

Does Oracle have a similar mechanism?  I realize I could use the following query to check if a table exists or not

    SELECT * FROM dba_tables where table_name = &#39;table_name&#39;;

but the syntax for tying that together with a &lt;code&gt;DROP&lt;/code&gt; is escaping me.

Oracle: If Table Exists

I&#39;m trying to delete all tables from a database except one, and I end up having the following error:

&gt;    Cannot delete or update a parent row: a foreign key constraint fails 

Of course I could trial and error to see what those key constraints are and eventually delete all tables but I&#39;d like to know if there is a fast way to force drop all tables (as I&#39;ll be able to re-insert those I don&#39;t want deleted).

Google aimed me at some site that suggested the following method:

    mysql&gt; SET foreign_key_checks = 0;
    mysql&gt; drop table ...
    mysql&gt; SET foreign_key_checks = 1;

Short answer is it didn&#39;t really do the trick since I ended up receiving the same error while I was able to delete some more tables. I&#39;ve seen on Stack Overflow ways to get all foreign keys linked to a certain table but that&#39;s way too time consuming unless I script it all (which is doable in the case there is no other option)

Database is 4.1 so I can&#39;t use `DROP DATABASE`

Ideas?


Content Type	Original Author	Original Content on Stackoverflow
Question	Teflon Ted	View Question on Stackoverflow
Solution 1 - Mysql	AvatarKava	View Answer on Stackoverflow
Solution 2 - Mysql	tvanfosson	View Answer on Stackoverflow
Solution 3 - Mysql	Daniel Schneller	View Answer on Stackoverflow

Does dropping a table in MySQL also drop the indexes?

Mysql Problem Overview

Mysql Solutions

Solution 1 - Mysql

Solution 2 - Mysql

Solution 3 - Mysql

String to byte array in php

Is it a good idea to use an integer column for storing US ZIP codes in a database?

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