100 characters. 

This is the *var* (variable) in `varchar`: you only store what you enter (and an extra 2 bytes to store length upto 65535)

If it was `char(200)` then you&#39;d always store 200 characters, padded with 100 spaces

See the docs: [&quot;The CHAR and VARCHAR Types&quot;][1]


  [1]: http://dev.mysql.com/doc/refman/5.0/en/char.html

&gt; VARCHAR means that it&#39;s a variable-length character, so it&#39;s only
&gt; going to take as much space as is necessary. But if you knew something
&gt; about the underlying structure, it may make sense to restrict VARCHAR
&gt; to some maximum amount.
&gt; 
&gt; For instance, if you were storing comments from the user, you may
&gt; limit the comment field to only 4000 characters; if so, it doesn&#39;t
&gt; really make any sense to make the sql table have a field that&#39;s larger
&gt; than VARCHAR(4000).

http://dev.mysql.com/doc/refman/5.0/en/char.html



Actually, it will takes 101 bytes.

[MySQL Reference][1]


  [1]: http://dev.mysql.com/doc/refman/5.0/en/char.html

I have query in a stored procedure that calls some linked servers with some dynamic SQL. I understand that EF doesn&#39;t like that, so I specifically listed all the columns that would be returned. Yet, it still doesn&#39;t like that. What am I doing wrong here? I just want EF to be able to detect the columns returned from the stored procedure so I can create the classes I need.

Please see the following code that makes up the last lines of my stored procedure:

    SELECT
	    #TempMain.ID,
	    #TempMain.Class_Data,
	    #TempMain.Web_Store_Class1,
	    #TempMain.Web_Store_Class2,
	    #TempMain.Web_Store_Status,
	    #TempMain.Cur_1pc_Cat51_Price,
	    #TempMain.Cur_1pc_Cat52_Price,
    	#TempMain.Cur_1pc_Cat61_Price,
	    #TempMain.Cur_1pc_Cat62_Price,
	    #TempMain.Cur_1pc_Cat63_Price,
	    #TempMain.Flat_Length,
	    #TempMain.Flat_Width,
	    #TempMain.Item_Height,
	    #TempMain.Item_Weight,
	    #TempMain.Um,
	    #TempMain.Lead_Time_Code,
	    #TempMain.Wp_Image_Nme,
	    #TempMain.Wp_Mod_Dte,
	    #TempMain.Catalog_Price_Chg_Dt,
	    #TempMain.Description,
	    #TempMain.Supersede_Ctl,
	    #TempMain.Supersede_Pn,
    	TempDesc.Cust_Desc,
	    TempMfgr.Mfgr_Item_Nbr,
	    TempMfgr.Mfgr_Name,
	    TempMfgr.Vendor_ID
    FROM
    	#TempMain
    		LEFT JOIN TempDesc ON #TempMain.ID = TempDesc.ID
		    LEFT JOIN TempMfgr ON #TempMain.ID = TempMfgr.ID

EF4 - The selected stored procedure returns no columns

In a for loop like this one:

    for f in `ls *.avi`; do echo $f; ffmpeg -i $f $f.mp3; done

$f will be the complete filename, including the extension. For example, for song1.avi the output of the command will be song1.avi.mp3. Is there a way to get only song1, without the .avi from the for loop?

I imagine there are ways to do that using awk or other such tools, but I&#39;m hoping there&#39;s something more straight forward.

Thanks

File name without extension in bash for loop

If I have a VARCHAR of 200 characters and that I put a string of 100 characters, will it use 200 bytes or it will just use the actual size of the string?

MySQL VARCHAR size?

<p>If I have a VARCHAR of 200 characters and that I put a string of 100 characters, will it use 200 bytes or it will just use the actual size of the string?</p>


This is probably an easy one... how can I achieve what i want with this query:

    delete from posts where id not in
    (SELECT id FROM posts order by timestamp desc limit 0, 15)

so, to put it in a nutshell, I want to delete every post that isn&#39;t on the latest 15.

When I try that query, I get that 

&gt; MySQL doesn&#39;t yet support &#39;LIMIT &amp;amp; IN/ALL/ANY/SOME subquery

EDIT

    mySQL Server version: 5.5.8
    mySQL Client version: mysqlnd 5.0.7-dev - 091210 - $Revision: 304625 $

&gt; Error: #1235 - This version of MySQL doesn&#39;t yet support &#39;LIMIT &amp;amp;
&gt; IN/ALL/ANY/SOME subquery&#39;



mySQL subquery limit

How can I display and count the values whose dates are yesterday?
I used `time()` to insert date in the database. Example:

    URL: google.com youtube.com google.com youtube.com test.com youtube.com
    DateVisited: 1313668492 1313668540 1313668571 13154314
    
I want do display how many URLs that have multiple existed in the table and also how many of that URL have been visited yesterday. Example result:

    LINK       | timesExisted | timesVisitedYesterday
    Google.com |       2      | 2
    youtube.com|       3      | 3

I already have the idea on getting yesterday&#39;s date, but I don&#39;t have an idea on counting how many times a URL has existed for yesterday and counting how many times a URL has existed in the table.

MySQL selecting yesterday&#39;s date

I was reading this question here:

https://stackoverflow.com/questions/1196415/what-datatype-to-use-when-storing-latitude-and-longitude-data-in-sql-databases

And it seems the general consensus is that using Decimal(9,6) is the way to go. The question for me is, how accurate do I really need this?

For instance, Google&#39;s API returns a result like:

    &quot;lat&quot;: 37.4219720,
    &quot;lng&quot;: -122.0841430

Out of -122.0841430, how many digits do I need? I&#39;ve read several guides but I can&#39;t make enough sense out of them to figure this out.

To be more precise in my question: If I want to be accurate within 50 feet of the exact location, how many decimal points do I need to store?

Perhaps a better question would actually be a non-programming question, but it would be: how much more accurate does each decimal point give you?

Is it this simple?

 1. List item
 2. x00 = 6000 miles
 3. xx0 = 600 miles
 4. xxx = 60 miles
 5. xxx.x = 6 miles
 6. xxx.xx = .6 miles
 7. etc?

How accurately should I store latitude and longitude?

I have seen many queries with something as follows.

    Select 1  
    From table

What does this `1` mean, how will it be executed and, what will it return?

Also, in what type of scenarios, can this be used?

What does it mean by select 1 from table?

Is there an easy way (i.e. a configuration) to force ActiveRecord to save empty strings as NULL in the DB (if the column allows)? 

The reason for this is that if you have a NULLable string column in the DB without a default value, new records that do not set this value will contain NULL, whereas new records that set this value to the empty string will not be NULL, leading to inconsistencies in the database that I&#39;d like to avoid.

Right now I&#39;m doing stuff like this in my models:

    before_save :set_nil

    def set_nil
      [:foo, :bar].each do |att|
        self[att] = nil if self[att].blank?
      end
    end

which works but isn&#39;t very efficient or DRY. I could factor this out into a method and mix it into ActiveRecord, but before I go down that route, I&#39;d like to know if there&#39;s a way to do this already.

Rails: Force empty string to NULL in the database

I need to update a field in my production db from INT to VARCHAR. 

The information in the current INT field is sensitive and I want to ensure that I don&#39;t alter it inadvertently or destroy it while changing the table type. For example, a user may have INT 123456 stored in this column and I want to ensure that is accurately stored once converted to VARCHAR.

What is the recommended process for accomplishing this? 

Is there anything I need to worry about when using something like this?

    ALTER TABLE table_sample CHANGE col_sample col_sample VARCHAR;


Thanks in advance for any help. 

How will changing the mysql field type from INT to VARCHAR affect data previously stored as an INT

I&#39;m using SQL Server 2008 and I need to make a VARCHAR field bigger, from (200 to 1200) on a table with about 500k rows.  What I need to know is if there are any issues I have not considered. 

I will be using this TSQL statement:

    ALTER TABLE MyTable
    ALTER COLUMN [MyColumn] VARCHAR(1200)

I&#39;ve already tried it on a copy of the data and this statement had no ill effects that I could see. 

So are there any possible problems from doing this that I may not have considered? 

By the way, the column is not indexed. 

When increasing the size of VARCHAR column on a large table could there be any problems?

I have a question about the `ALTER TABLE` command on a really large table (almost 30 millions rows).
One of its columns is a `varchar(255)` and I would like to resize it to a `varchar(40)`.
Basically, I would like to change my column by running the following command:

```sql
ALTER TABLE mytable ALTER COLUMN mycolumn TYPE varchar(40);
```

I have no problem if the process is very long but it seems my table is no more readable during the `ALTER TABLE` command.
Is there a smarter way? Maybe add a new column, copy values from the old column, drop the old column and finally rename the new one?

**Note:** I use PostgreSQL 9.0.

Postgresql - change the size of a varchar column to lower length

I&#39;m trying to update the length of a varchar column from 255 characters to 500 without losing the contents. I&#39;ve dropped and re-created tables before but I&#39;ve never been exposed to the alter statement which is what I believe I need to use to do this. I found the documentation here: [ALTER TABLE (Transfact-SQL)][1] however I can&#39;t make heads or tails of it.

I have the following so far (essentially nothing unfortunately):

    alter table [progennet_dev].PROGEN.LE
  	alter column UR_VALUE_3

How do I approach this? Is there better documentation for this statement out there (I did some searches for an example statement but came up empty)?


  [1]: http://msdn.microsoft.com/en-us/library/ms190273.aspx

Changing the maximum length of a varchar column?

I have to get last 5 numbers using mysql.

My values are like `YOT-A78514`,`LOP-C4521` ...

I have to get only last five char . How can I do this in query?

Content Type	Original Author	Original Content on Stackoverflow
Question	SBSTP	View Question on Stackoverflow
Solution 1 - Mysql	gbn	View Answer on Stackoverflow
Solution 2 - Mysql	dwmcc	View Answer on Stackoverflow
Solution 3 - Mysql	panoet	View Answer on Stackoverflow

MySQL VARCHAR size?

Mysql Problem Overview

Mysql Solutions

Solution 1 - Mysql

Solution 2 - Mysql

Solution 3 - Mysql

File name without extension in bash for loop

EF4 - The selected stored procedure returns no columns

Attributions