A `BLOB` can be 65535 bytes (64 KB) maximum. 

If you need more consider using:

- a `MEDIUMBLOB` for 16777215 bytes (16 MB)

- a `LONGBLOB` for 4294967295 bytes (4 GB). 

See [Storage Requirements for String Types][1] for more info.


  [1]: http://dev.mysql.com/doc/refman/5.5/en/storage-requirements.html#id899830

May or may not be accurate, but according to this site: [http://www.htmlite.com/mysql003.php][1]. 

&gt; BLOB	A string with a maximum length of 65535 characters.

The MySQL manual says:

&gt; The maximum size of a BLOB or TEXT
&gt; object is determined by its type, but
&gt; the largest value you actually can
&gt; transmit between the client and server
&gt; is determined by the amount of
&gt; available memory and the size of the
&gt; communications buffers

I think the first site gets their answers from interpreting the MySQL manual, per [http://dev.mysql.com/doc/refman/5.0/en/storage-requirements.html][2]


  [1]: http://www.htmlite.com/mysql003.php
  [2]: http://dev.mysql.com/doc/refman/5.0/en/storage-requirements.html

I&#39;m just wondering if there is any significant difference between an `ImageView` that&#39;s set to be clickable, compared with an `ImageButton`?  

Is there any reason for using one over the other? Is there any restriction on the drawable for an `ImageButton` that leaves `ImageView` as the only possible option?  

Will I possibly lose any functionality of a button if I opt for a clickable `ImageView` over `ImageButton`?

Difference between a clickable ImageView and ImageButton

I get this error whenever I submit the form also the action method is not being called because of this:

&gt; An item with the same key has already been added.

And the exception details:

&gt; [ArgumentException: An item with the
&gt; same key has already been added.]   
&gt; System.ThrowHelper.ThrowArgumentException(ExceptionResource
&gt; resource) +52   
&gt; System.Collections.Generic.Dictionary\`2.Insert(TKey
&gt; key, TValue value, Boolean add)
&gt; +9382923    System.Linq.Enumerable.ToDictionary(IEnumerable\`1
&gt; source, Func\`2 keySelector, Func\`2
&gt; elementSelector, IEqualityComparer\`1
&gt; comparer) +252   
&gt; System.Linq.Enumerable.ToDictionary(IEnumerable\`1
&gt; source, Func\`2 keySelector,
&gt; IEqualityComparer\`1 comparer) +91   
&gt; System.Web.Mvc.ModelBindingContext.get_PropertyMetadata()
&gt; +228    System.Web.Mvc.DefaultModelBinder.BindProperty(ControllerContext
&gt; controllerContext, ModelBindingContext
&gt; bindingContext, PropertyDescriptor
&gt; propertyDescriptor) +392   
&gt; System.Web.Mvc.DefaultModelBinder.BindProperties(ControllerContext
&gt; controllerContext, ModelBindingContext
&gt; bindingContext) +147   
&gt; System.Web.Mvc.DefaultModelBinder.BindComplexElementalModel(ControllerContext
&gt; controllerContext, ModelBindingContext
&gt; bindingContext, Object model) +98   
&gt; System.Web.Mvc.DefaultModelBinder.BindComplexModel(ControllerContext
&gt; controllerContext, ModelBindingContext
&gt; bindingContext) +2504   
&gt; System.Web.Mvc.DefaultModelBinder.BindModel(ControllerContext
&gt; controllerContext, ModelBindingContext
&gt; bindingContext) +548   
&gt; System.Web.Mvc.ControllerActionInvoker.GetParameterValue(ControllerContext
&gt; controllerContext, ParameterDescriptor
&gt; parameterDescriptor) +473   
&gt; System.Web.Mvc.ControllerActionInvoker.GetParameterValues(ControllerContext
&gt; controllerContext, ActionDescriptor
&gt; actionDescriptor) +181   
&gt; System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext
&gt; controllerContext, String actionName)
&gt; +830    System.Web.Mvc.Controller.ExecuteCore()
&gt; +136    System.Web.Mvc.ControllerBase.Execute(RequestContext
&gt; requestContext) +111   
&gt; System.Web.Mvc.ControllerBase.System.Web.Mvc.IController.Execute(RequestContext
&gt; requestContext) +39   
&gt; System.Web.Mvc.&lt;&gt;c__DisplayClass8.&lt;BeginProcessRequest&gt;b__4()
&gt; +65    System.Web.Mvc.Async.&lt;&gt;c__DisplayClass1.&lt;MakeVoidDelegate&gt;b__0()
&gt; +44    System.Web.Mvc.Async.&lt;&gt;c__DisplayClass8\`1.&lt;BeginSynchronous&gt;b__7(IAsyncResult
&gt; _) +42    System.Web.Mvc.Async.WrappedAsyncResult\`1.End()
&gt; +141    System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult
&gt; asyncResult, Object tag) +54   
&gt; System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult
&gt; asyncResult, Object tag) +40   
&gt; System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult
&gt; asyncResult) +52   
&gt; System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult
&gt; result) +38   
&gt; System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
&gt; +8836913    System.Web.HttpApplication.ExecuteStep(IExecutionStep
&gt; step, Boolean&amp; completedSynchronously)
&gt; +184

ViewPage
-------------------

    &lt;%@ Page Title=&quot;&quot; Language=&quot;C#&quot; MasterPageFile=&quot;~/Views/Shared/XYZ.Master&quot;
        Inherits=&quot;System.Web.Mvc.ViewPage&lt;XYZ.Models.Admin.AdminSegmentCommissionsModel&gt;&quot; %&gt;
        &lt;asp:Content ID=&quot;Content1&quot; ContentPlaceHolderID=&quot;TitleContent&quot; runat=&quot;server&quot;&gt;
            Create
        &lt;/asp:Content&gt;
        &lt;asp:Content ID=&quot;Content2&quot; ContentPlaceHolderID=&quot;MainContent&quot; runat=&quot;server&quot;&gt;
            &lt;% using (Html.BeginForm()) {%&gt;    
                &lt;div class=&quot;box3&quot;&gt;
                    &lt;div class=&quot;userinfo&quot;&gt;
                        &lt;h3&gt;Admin Segment Commissions&lt;/h3&gt;
                    &lt;/div&gt;
                    &lt;div class=&quot;buttons-panel&quot;&gt;
                        &lt;ul&gt;
                           &lt;li&gt;
                               &lt;input type=&quot;submit&quot; value=&quot;Save&quot; class=&quot;save&quot; /&gt;
                           &lt;/li&gt;
                           &lt;li&gt;
                               &lt;%:Html.ActionLink(&quot;Cancel&quot;, &quot;Index&quot;, new { controller = &quot;AdminSegmentCommissions&quot; }, new { @class = &quot;cancel&quot; })%&gt;
                               &lt;%--&lt;input type=&quot;button&quot; value=&quot;Cancel&quot; class=&quot;cancel&quot; onclick=&quot;document.location.href=&#39;/AirlineLedgerTransactionReceiver/Index&#39;&quot; /&gt;--%&gt;
                           &lt;/li&gt;
                       &lt;/ul&gt;
                   &lt;/div&gt;
               &lt;/div&gt;
               &lt;div class=&quot;row-1&quot;&gt;
                   &lt;div class=&quot;form-box1 round-corner&quot;&gt;
                       &lt;div class=&quot;form-box1-row&quot;&gt;
                           &lt;div class=&quot;form-box1-row-content float-left&quot;&gt;
                               &lt;div&gt;
                                   &lt;label&gt;
                                       &lt;%: Html.LabelFor(model =&gt; model.FromSegmentNumber) %&gt;&lt;/label&gt;
                                       &lt;%: Html.TextBoxFor(model =&gt; model.FromSegmentNumber) %&gt;
                                       &lt;%: Html.ValidationMessageFor(model =&gt; model.FromSegmentNumber) %&gt;
                              &lt;/div&gt;
                          &lt;/div&gt;
                      &lt;/div&gt;
                  &lt;/div&gt;
              &lt;/div&gt;
          &lt;%} %&gt;
&lt;/asp:Content&gt;
&lt;asp:Content ID=&quot;Content3&quot; ContentPlaceHolderID=&quot;CssContent&quot; runat=&quot;server&quot;&gt;
&lt;/asp:Content&gt;
&lt;asp:Content ID=&quot;Content4&quot; ContentPlaceHolderID=&quot;JSContent&quot; runat=&quot;server&quot;&gt;
&lt;/asp:Content&gt;



An item with the same key has already been added

What is the maximum length of data I can put in a BLOB column in MySQL?

<p>What is the maximum length of data I can put in a BLOB column in MySQL?</p>


What&#39;s the difference in a MySQL FK between `RESTRICT` and `NO ACTION`? From the doc they seem exactly the same. Is this the case? If so, why have both?

MySQL RESTRICT and NO ACTION

I have a table A and there is one primary key ID.

Now I want to go through all rows in A.

I found something like &#39;for each record in A&#39;, but this seems to be not how you do it in MySQL.

Thing is for each row I want to take a field and transform it, insert it into another table and then update some of the row&#39;s fields. I can put the select part and the insert into one statement, but I don&#39;t know how to get the update in there as well. So I want to loop. And for practice I don&#39;t want to use anything else than MySQL.

**edit**

I would appreciate an example.

And a solution which does not need to be put into a procedure.

**edit 2**

okay think of this scenario:

Table A and B, each with fields ID and VAL.

Now this is the pseudo code for what I want to do:

    for(each row in A as rowA)
    {
      insert into B(ID, VAL) values(rowA[ID], rowA[VAL]);
    }

basically copying content of A into B using a loop.

(this is just a simplified example, of course you wouldn&#39;t use a loop for this.)
}

How can I loop through all rows of a table? (MySQL)

I&#39;ve just started getting into Node.js. I come from a PHP background, so I&#39;m fairly used to using MySQL for all my database needs.

How can I use MySQL with Node.js?



  [1]: https://github.com/Guille/node.dbslayer.js

MySQL with Node.js

I have two columns in table users namely `registerDate and lastVisitDate` which consist of datetime data type. I would like to do the following.

 1. Set registerDate defaults value to MySQL NOW()
 2. Set lastVisitDate default value to `0000-00-00 00:00:00` Instead of null which it uses by default.

Because the table already exists and has existing records, I would like to use Modify table.  I&#39;ve tried using the two piece of code below, but neither works.  

    ALTER TABLE users MODIFY registerDate datetime DEFAULT NOW()
    ALTER TABLE users MODIFY registerDate datetime DEFAULT CURRENT_TIMESTAMP;

It gives me Error : `ERROR 1067 (42000): Invalid default value for &#39;registerDate&#39;`

Is it possible for me to set the default datetime value to NOW() in MySQL?

Set NOW() as Default Value for datetime datatype?

I have the following MySql query:

    select t1.*
    from Table1 t1
    inner join Table2 t2
    on t1.CommonID = t2.CommonID
    where t1.FilterID = 1

It takes about 30 seconds to run, which was strange, because if I comment out the join or the where clause it takes less than a second:
i.e.

    select t1.*
    from Table1 t1
    where t1.FilterID = 1

or

    select t1.*
    from Table1 t1
    inner join Table2 t2
    on t1.CommonID = t2.CommonID

each take less than a second.

Then there is the STRAIGHT_JOIN keyword, which I can find one reference of, here:
[http://dev.mysql.com/doc/refman/5.0/en/join.html][1]

&gt; STRAIGHT_JOIN is similar to JOIN,
&gt; except that the left table is always
&gt; read before the right table. This can
&gt; be used for those (few) cases for
&gt; which the join optimizer puts the
&gt; tables in the wrong order.

What?
I can write:

    select t1.*
    from Table1 t1
    STRAIGHT_JOIN  Table2 t2
    on t1.CommonID = t2.CommonID
    where t1.FilterID = 1

and the query executes in less than a second.

Even stranger, I can write:

    select STRAIGHT_JOIN  t1.*
    from Table1 t1
    inner join Table2 t2
    on t1.CommonID = t2.CommonID
    where t1.FilterID = 1

and it takes less than a second, and this syntax does not appear to even be legal.

I would guess the second example means that a STRAIGHT_JOIN will be used whenever an INNER JOIN is written, but I can’t find any documentation about it.

What is going on here, and how can the “join optimizer” result in such relatively poor performance?  Should I always use STRAIGHT_JOIN?  How can I tell when to use it or not?

Table1 and Table2 both have integer primary keys; FilterID is a foreign key to another table; the CommonID columns are both foreign keys to a third table.  They both have indexes on them.  The database engine is InnoDB.

Thanks


  [1]: http://dev.mysql.com/doc/refman/5.0/en/join.html

Why does STRAIGHT_JOIN so drastically improve this query, and what does it mean when it is written after the SELECT keyword?

what is the easiest way to convert a Blob into a byte array?I am using MYSQL and i want to convert a Blob datatype into a byte array.

Iam using java programming language:)


Easiest way to convert a Blob into a byte array

I want to store an image(from url) into a sqlite database.

For that I use: 

    db = new DataBase(getApplicationContext());
    URL url = new URL(&quot;http://sree.cc/wp-content/uploads/schogini_team.png&quot;);
    URLConnection ucon = url.openConnection();
    InputStream is = ucon.getInputStream();
    BufferedInputStream bis = new BufferedInputStream(is,128);
    ByteArrayBuffer barb= new ByteArrayBuffer(128);
    
    int current = 0;
    while ((current = bis.read()) != -1) {
    	barb.append((byte) current);
    }
    
    ContentValues filedata= new ContentValues();
    
    filedata.put(DataBase.IMG_SRC,barb.toByteArray());
    
    db.insert(DataBase.Table_Img, null, filedata);

In the `Insert()`:

    public void insert(String tableImg, Object object,
    		ContentValues dataToInsert) {
    	// TODO Auto-generated method stub
    	String sql = &quot;INSERT INTO &quot;+tableImg+&quot; (&quot;+ID+&quot;,&quot;+IMG_SRC+&quot;) &quot; +
    			&quot;VALUES (&#39;&quot;+1+&quot;&#39;,&#39;&quot;+dataToInsert+&quot;&#39;)&quot;;
    	db.execSQL(sql);
    }


For the retrieval of image:

    Cursor cursor = db.selectDataToShow(DataBase.Table_Img, DataBase.IMG_SRC);
    
    byte[] imageByteArray=cursor.getBlob(cursor.getColumnIndex(DataBase.IMG_SRC));    	
    cursor.close();
    
    ByteArrayInputStream imageStream = new ByteArrayInputStream(imageByteArray);
    Bitmap theImage = BitmapFactory.decodeStream(imageStream);
    
    System.out.println(&quot;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt; &quot;+theImage);

So here I got `null`.

And in my database the value of image stored as: `Image=[B@43e5ac48]`

how to store Image as blob in Sqlite &amp; how to retrieve it?

I am retrieving a Blob image from a database, and I&#39;d like to be able to view that image using JavaScript. The following code produces a broken image icon on the page:

    var image = document.createElement(&#39;image&#39;);
        image.src = &#39;data:image/bmp;base64,&#39;+Base64.encode(blob);
        document.body.appendChild(image);

[Here is a jsFiddle][1] containing all the code required, including the blob. The completed code should properly display an image.

 [1]:http://jsfiddle.net/PDhCy/1/

Using JavaScript to display a Blob

Is ok storing files like HTML pages, images, PDF, etc in a table in PostgreSQL or it is slow? I read some articles saying that this is not recommended, but I don&#39;t know if is true.

The column types I have in mind are `BLOB` (as far as I know it stores in a file) or `bytea` type, but others are applicable also.

Are there performance issues storing files in PostgreSQL?

I am planning to store a `json_encoded` string on my database. I can&#39;t precisely tell the length its going to be, but I&#39;m pretty sure it will be long. My concern is which field type I am going to use for this, is it `blob` or `text`?

I prefer the one where I can save space as much as possible over fast searching, in any case I have other column where I should just index.

Content Type	Original Author	Original Content on Stackoverflow
Question	Newy	View Question on Stackoverflow
Solution 1 - Mysql	WhiteFang34	View Answer on Stackoverflow
Solution 2 - Mysql	Tieson T.	View Answer on Stackoverflow

What is the maximum length of data I can put in a BLOB column in MySQL?

Mysql Problem Overview

Mysql Solutions

Solution 1 - Mysql

Solution 2 - Mysql

An item with the same key has already been added

Difference between a clickable ImageView and ImageButton

Attributions