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How to run many scripts in MySQL

2009-07-05T07:35:00.000-07:00

In some projects, the database schema changes day by day. For every changes, we have a script to update database. This causes we will have many scripts regarding the changes. In fact, we can merge these scripts into one main script. However, it is not easy to keep track changes of db between releases. For every time create database(maybe for testing), we have to run many scripts in sequence, it takes time :). I have tried by using command:

mysql> source script1.sql, script2.sql,..

but it doesn't work.

To do this, we can create an shell script(Unix ) or an bat file(Window). The content of the file is just commands to run scripts we need.

The syntax is:

mysql -uusername -ppassword -D database_name < script

For ex:
below is a shell script to run script1.sql, script2.sql, script3.sql in sequence automatically. This

mysql -u root -ppassword -D shopping < c:/script1.sql
mysql -u root -ppassword -D shopping < c:/script2.sql
mysql -u root -ppassword -D shopping < c:/script3.sql

From now, to create database, the only thing we need is to run this bat file or shell script file.

2009-02-05T03:37:00.000-08:00

Interview Questions

If you are searching for Interview Questions related to Java Technologies,
then the below may be of intrest to you, so, please visit the below:

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What is error 28 and how to avoid it

2009-02-05T03:34:00.000-08:00

Using the command line tool perror you can find out, what the error 28 means.

> perror 28
Error code 28: No space left on device

If you get his error, you need to check all filesystems where MySQL operates. It may be single filesystem or as we recommend you can have datadir, tmpdir and log files split into dedicated filesystems. MySQL often creates temporary tables for some queries - most of them are placed in tmpdir, but some into database directory (e.g. ALTER TABLE). You must ensure, that there is enough free disk space available for MySQL.

You can check out, that environment variables for MySQL are properly set.

Check the value of tmp_table_size:

mysql> show variables like “tmp_table_size”;
+—————-+———-+
| Variable_name | Value |
+—————-+———-+
| tmp_table_size | 33554432 |
+—————-+———-+

This tells, what is the limit, when reached, in-memory temporary tables will automatically be converted to a disk-based MyISAM table.

Then you need to find out, where the ‘tmpdir’ points

mysql> show variables like “tmpdir”;
+—————+————-+
| Variable_name | Value |
+—————+————-+
| tmpdir | /var/tmp/mysql/ |
+—————+————-+

And check, that there is plenty of space available in that device.

In my case, when I type: df -h

….

/dev/dsk/c0d0s1 9.6G 9.6G 0K 100% /var

…

The “/var“ is full, so I got error 28. I tried to change to “tmpdir” to another location that have available space(edit /etc/my.cnf) and mysql run ok now.

Eclipse Shortcut

2009-02-05T03:14:00.000-08:00

Some useful and commonly used Java Eclipse Shortcuts. This will improve your work efficiency in Eclipse.

F1 To get help context message
F1 To show error message in wizard dialog
F3 Back to corresponding source code
Ctrl+F6 For switching to different editors
Ctrl+F7 For switching to different views
Ctrl+F8 Switch to different perspective
Ctrl+shift+Arrow-up Jumping from one method to previous method
Ctrl+shift+Arrow-down Jumping from one method to next method
Alt+Shift+P Navigating between matching braces
Ctrl+O Navigating between different parts of the code
Ctrl+, and Ctrl+. To find the syntax errors in a code