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[/software/database/mysql] permanent link

# mysqldump -p --databases partsdb > partsdb-20111016.sql
Enter password:

In the above example, the -p option causes mysql to prompt for the mysql account password with the username assumed to be the same as the login name for the account from which you are running the command. If you wish to specify the username, use --user=user_name or -u user_name.

If you want to back up all databases you can use the command mysqldump --all-databases > dump.sql to back up all databases to which the account has access on the system to a file named dump.sql in this case.

A dump file can be used in several ways:

• As a backup to enable data recovery in case of data loss.

• As a source of data for setting up replication slaves.

• As a source of data for experimentation:

  • To make a copy of a database that you can use without changing the original data.

  • To test potential upgrade incompatibilities.

An example script to dump mysql databases to a gzip file which will be transferred to another server via SSH for safekeeping can be found at How to have a rock solid Linux backup without pro budget. Placing you dump file on another system ensures you don't lose your data should the system on which your databases reside suffer a hard drive crash or some other catastrophe.

References:

1. 6.4.1. Dumping Data in SQL Format with mysqldump
   MySQL :: Developer Zone
2. 6.4. Using mysqldump for Backups
   MySQL :: Developer Zone
3. How to have a rock solid Linux backup without pro budget
   documentation planet

[/software/database/mysql] permanent link

For example, if I issue the statement DROP TABLE IF EXISTS smf_testing statement as below, I see a notice that 0 rows were affected, but there was 1 warning. To see the warning, I can immediately afterwards issue the statement SHOW WARNINGS. I see that the warning was simply indicating that the table I asked be dropped, didn't actually exist.

mysql> DROP TABLE IF EXISTS smf_testing;
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> SHOW WARNINGS;
+-------+------+-----------------------------+
| Level | Code | Message                     |
+-------+------+-----------------------------+
| Note  | 1051 | Unknown table 'smf_testing' |
+-------+------+-----------------------------+
1 row in set (0.00 sec)

mysql>

References:

1. 12.4.5.41. SHOW WARNINGS Syntax
   MySQL :: Developer Zone

[/software/database/mysql] permanent link

create table New_Table like Existing_Table;

New_Table = the name you wish to give to the new table
Existing_Table = the name of the existing table

Remember to use the same case of letters for the existing table name as were actually used for that table name. E.g., if the table name is "Existing_Table" use "Existing_Table" not "existing_table"

[/software/database/mysql] permanent link

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[/software/database/collectorz/MC-Customization] permanent link

Once you have the software installed and configured, you can set up a new database using the instructions in Creating a MySQL Database.

[/software/database/mysql] permanent link

1. Start the text-based MySQL client
   
   $ mysql -u testacct -p
   
   The -u testacct parameter specifies that the client should be started using the account named testacct, while the -p parameter indicates that the system should prompt you for the password.



2. At the mysql> prompt, enter the command use dbname;, where dbname is the database name. If you don't know the name of the database, you can see a list of available databases with the show databases; command.



3. Use the alter table command to modify the appropriate table. If you need to see a list of tables in the database, you can use the show tables; command. E.g. to add a column, delivered, which will hold a delivery date for a shipment, to the table requests, you could use the command below:
   
   ALTER TABLE requests ADD delivered DATE;
   
   That would put the new column at the end of the existing columns. If you want to add the column after a specific column, you can specify that column with AFTER colname. E.g., suppose I wish to add the column delivered after the column orderdate. I could use the command below:
   
   ALTER TABLE requests ADD delivered DATE AFTER orderdate;
   
   If you don't know the names of the existing columns, you can use the command SHOW COLUMNS FROM dbname;. E.g., if the table is named requests, I could use the command below:
   
   mysql> show columns from requests;

References:

1. Add a column to an existing MySQL table
   Created: February 8, 2004
   Updated: July 17, 2004
   tech-recipes

[/software/database/mysql] permanent link

I wanted to be able to double-click on the drive serial number in the "External" form and have the "HDD" form open with the record displayed with the corresponding serial number, so that I could view all of the information on the particular hard disk drive within the drive enclosure that I had selected in the "External" form. I used the following procedure to be able to do so.

1. In the drive serial number field of the "external" form, I right-clicked and chose Properties.
2. Scrolled down to the "On Dbl Click" field.
3. I clicked on the button with "..." on it.
4. I chose Macro Builder and clicked on OK.
5. I gave it a name of OpenHDD and clicked on OK.
6. For Action, I chose OpenForm.
7. In the Form Name field, I put in HDD, the name of the form that displays information on the hard disk drives.
8. For View, I selected Form.
9. For Where Condition, I clicked on the "..." button and chose Tables then the HDD table beneath it.
10. I then selected Serial Number in the next column and double-clicked on <Value> in the last column, which gave me [HDD]![Serial Number] in the Expression Builder field.
11. I then clicked on the equal button to add = at the end of the expression and then added Forms![External]![Serial Number] giving me [HDD]![Serial Number] = Forms![External]![Drive SN] .
12. I then clicked on OK
13. For the Comment field, which is to the right of the Action field, I put "Open HDD form to drive corresponding to External drive SN"
14. I then closed the Expression Builder window, saving the macro.
15. I then closed the Properties window that was open for the Drive SN field.

I was then able to click on the drive serial number field in the External form and have the HDD form open displaying the information on the hard disk drive within the enclosure.

[/software/database/access] permanent link

Sleepycat's Berkeley DB may be the most sidely used open-source database software with an estimated 200 million deployments. Bekeley DB is a programmatic toolkit that provides fast, reliable, scalable, and mission-critical database support to software developers. I use it for makemap hash support for Sendmail.

References:

1. Oracle Pounces on Sleepycat
   By John G. Spooner
   eweek.com
   February 14, 2006
2. Installing Sendmail on Solaris

[/software/database] permanent link