As described in [Cast Functions and Operators](http://dev.mysql.com/doc/en/cast-functions.html#function_cast):

&gt; The type for the result can be one of the following values:
&gt;
&gt; * `BINARY[(N)]`
&gt; * `CHAR[(N)]`
&gt; * `DATE`
&gt; * `DATETIME`
&gt; * `DECIMAL[(M[,D])]`
&gt; * `SIGNED [INTEGER]`
&gt; * `TIME`
&gt; * `UNSIGNED [INTEGER]`

Therefore, you should use:

    SELECT CAST(PROD_CODE AS UNSIGNED) FROM PRODUCT

For casting varchar fields/values to number format can be little hack used:

    SELECT (`PROD_CODE` * 1) AS `PROD_CODE` FROM PRODUCT`



Using storyboard this is very easy. You just drag the action to &quot;Exit&quot;. But how should I call it from my code?

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My Current Data for

    SELECT PROD_CODE FROM `PRODUCT`

is

    PROD_CODE
    2
    5
    7
    8
    22
    10
    9
    11

I have tried all the four queries and none work. ([Ref][1])

    SELECT CAST(PROD_CODE) AS INT FROM PRODUCT;

    SELECT CAST(PROD_CODE AS INT) FROM PRODUCT;

    SELECT CAST(PROD_CODE) AS INTEGER FROM PRODUCT;

    SELECT CAST(PROD_CODE AS INTEGER) FROM PRODUCT;


All throw syntax errors such as below:

&gt; You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use
&gt; near &#39;) AS INT FROM PRODUCT LIMIT 0, 30&#39; at line 1
&gt; 
&gt; You have an error in your SQL syntax; check the manual that
&gt; corresponds to your MySQL server version for the right syntax to use
&gt; near &#39;INTEGER) FROM PRODUCT LIMIT 0, 30&#39; at line 1

What is the right syntax to cast varchar to integer in MySQL?

MySQL Version: 5.5.16


  [1]: http://dev.mysql.com/doc/refman/5.5/en/cast-functions.html#function_cast



Cast from VARCHAR to INT - MySQL

My Current Data for
<pre><code class="hljs language-sql">SELECT PROD_CODE FROM `PRODUCT`
</code></pre>
is
<pre><code class="hljs">PROD_CODE
2
5
7
8
22
10
9
11
</code></pre>
I have tried all the four queries and none work. (<a href="http://dev.mysql.com/doc/refman/5.5/en/cast-functions.html#function_cast" target="_blank" rel="noopener noreferrer">Ref</a>)
<pre><code class="hljs language-sql">SELECT CAST(PROD_CODE) AS INT FROM PRODUCT;

SELECT CAST(PROD_CODE AS INT) FROM PRODUCT;

SELECT CAST(PROD_CODE) AS INTEGER FROM PRODUCT;

SELECT CAST(PROD_CODE AS INTEGER) FROM PRODUCT;
</code></pre>
All throw syntax errors such as below:
> You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use
> near ') AS INT FROM PRODUCT LIMIT 0, 30' at line 1
>
> You have an error in your SQL syntax; check the manual that
> corresponds to your MySQL server version for the right syntax to use
> near 'INTEGER) FROM PRODUCT LIMIT 0, 30' at line 1
What is the right syntax to cast varchar to integer in MySQL?
MySQL Version: 5.5.16

It [appears](https://stackoverflow.com/q/1433978/1593077) that MySQL doesn&#39;t have array variables. What should I use instead? 

------
There seem to be two alternatives suggested: A **set-type scalar** and **temporary tables**. The question I linked to suggests the former. But is it good practice to use these instead of array variables? Alternatively, if I go with sets, what would be the set-based idiom equivalent to `foreach`? 

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I have the following table in MySQL version 5.5.24

    DROP TABLE IF EXISTS `momento_distribution`;
    
    CREATE TABLE IF NOT EXISTS `momento_distribution`
      (
         `momento_id`       INT(11) NOT NULL,
         `momento_idmember` INT(11) NOT NULL,
         `created_at`       DATETIME DEFAULT NULL,
         `updated_at`       DATETIME DEFAULT NULL,
         `unread`           TINYINT(1) DEFAULT &#39;1&#39;,
         `accepted`         VARCHAR(10) NOT NULL DEFAULT &#39;pending&#39;,
         `ext_member`       VARCHAR(255) DEFAULT NULL,
         PRIMARY KEY (`momento_id`, `momento_idmember`),
         KEY `momento_distribution_FI_2` (`momento_idmember`),
         KEY `accepted` (`accepted`, `ext_member`)
      )
    ENGINE=InnoDB
    DEFAULT CHARSET=latin1;

It has lots of data with many-to-one relations with two other tables with `ondelete=restrict` and `onupdate=restrict`.

Now, I need to change the structure and introduce separate primary key in the table, while still keeping existing relations and data. For that, I executed the following query:

    ALTER TABLE  `momento_distribution` ADD  `id` INT( 11 ) NOT NULL FIRST;
    ALTER TABLE  `momento_distribution` DROP PRIMARY KEY , ADD PRIMARY KEY (  `id` );

Unfortunately, my second query failed with the following error:

&gt; 1062 - Duplicate entry &#39;0&#39; for key &#39;PRIMARY&#39;

Can someone please point out the issue? I guess that the issue is the existing relation, but I don&#39;t want to lose the existing relation or data, that has several thousand rows. Is there any way to do this without losing data?

**EDIT:**
By viewing data, I got that the newly created column has the  value &#39;0&#39; in it. Probably this is not allowing to change the Primary Key due to duplicate records (in new Primary Key)

I have more than 8,000 rows, so I can&#39;t change it manually. Is there any way to assign `rowid` to a new Primary Key?

MySQL 1062 - Duplicate entry &#39;0&#39; for key &#39;PRIMARY&#39;

Let&#39;s say I have columns `a, b c, d` in a table in a MySQL database. What I&#39;m trying to do is to select the distinct values of ALL of these 4 columns in my table (only the distinct values). I tried stuff like:

    SELECT DISTINCT a,b,c,d FROM my_table;
    SELECT DISTINCT a,b,c,d FROM my_table GROUP BY a,b,c,d;

None of those worked. Can anybody help out here?

Thank you

**NOTE** I want the distinct values of the columns `a, b, c d` separately. Not the distinct combination of values

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I created a database with the name of `hrms`. Now I need to change database name to `sunhrm`. But, It is disabled in MySQL workbench. Can I do that on the Linux server itself?

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SHOW PROCESSLIST in MySQL command: sleep

By looking at other examples I&#39;ve come up with the following but it doesn&#39;t seem to work as I would like: I want it to only update the modified information if the `QtyToRepair` value has been updated... but it doesn&#39;t do that. 

If I comment out the where then the modified information is updated in every case. As I said other examples led me to be optimistic. Any clues appreciated. Thanks.

Walter

    ALTER TRIGGER [dbo].[tr_SCHEDULE_Modified]
       ON [dbo].[SCHEDULE]
       AFTER UPDATE
    AS 
    BEGIN
    	SET NOCOUNT ON;

	    UPDATE SCHEDULE	SET modified = GETDATE()
		    , ModifiedUser = SUSER_NAME()
    		, ModifiedHost = HOST_NAME()
	    FROM SCHEDULE S
    	INNER JOIN Inserted I on S.OrderNo = I.OrderNo and S.PartNumber = I.PartNumber
    	WHERE S.QtyToRepair &lt;&gt; I.QtyToRepair
    END

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I want to do conversion in T-SQL from a `varbinary` type to string type

Here is an example :

First I got this `varbinary`

    0x21232F297A57A5A743894A0E4A801FC3

And then I want to convert it to 

    21232f297a57a5a743894a0e4a801fc3

How to do this?

SQL Server converting varbinary to string

I am testing Postgres insertion performance. I have a table with one column with number as its data type. There is an index on it as well. I filled the database up using this query:

    insert into aNumber (id) values (564),(43536),(34560) ...

I inserted 4 million rows very quickly 10,000 at a time with the query above. After the database reached 6 million rows performance drastically declined to 1 Million rows every 15 min. Is there any trick to increase insertion performance? I need optimal insertion performance on this project.

Using Windows 7 Pro on a machine with 5 GB RAM.

Content Type	Original Author	Original Content on Stackoverflow
Question	Lenin Raj Rajasekaran	View Question on Stackoverflow
Solution 1 - Mysql	eggyal	View Answer on Stackoverflow
Solution 2 - Mysql	Jirka Kopřiva	View Answer on Stackoverflow

Cast from VARCHAR to INT - MySQL

Mysql Problem Overview

Mysql Solutions

Solution 1 - Mysql

Solution 2 - Mysql

When is std::weak_ptr useful?

How to perform Unwind segue programmatically?

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