Portability fixes.

if ($opt_stage <= 2)

{

  unlink($opt_distribution) if (!$opt_delete && !$opt_use_old_distribution);

  unlink($opt_distribution) if ($opt_delete && !$opt_use_old_distribution);

  safe_system("$make");

}

uses MySQL with 60,000 tables and about 5,000,000,000 rows

@item

All columns have default values.  You can use @code{INSERT} to insert a

subset of a table's columns; those columns that are not explicitly given

values are set to their default values.

@cindex default values

All columns have default values.

You can use @code{INSERT} to insert a subset of a table's columns; those

columns that are not explicitly given values are set to their default

values.

@item

Uses GNU Automake, Autoconf, and Libtool for portability.

We are also working on some extensions to solve this problem for some

common application niches.

MySQL can work with both transactional and not transactional tables.  To

be able to work smoothly with not transactional tables (which can't

rollback if something goes wrong), MySQL has the following rules:

@cindex default values

@itemize @bullet

@item

All columns has default values.

@item

If you insert a 'wrong' value in a column like a @code{NULL} in a

@code{NOT NULL} column or a too big numerical value in a numerical

column, MySQL will instead of giving an error instead set the column to

the 'best possible value'.  For numerical values this is 0, the smallest

possible values or the largest possible value. For strings this is

either the empty string or the longest possible string that can be in

the column.

@item

All calculated expressions returns a value that can be used instead of

signaling an error condition. For example 1/0 returns @code{NULL}

@end itemize

The reason for the above rules is that we can't check these conditions

before the query starts to execute.  If we encounter a problem after

updating a few rows, we can't just rollback as the table type may not

support this.  We can't stop because in that case the update would be

'half done' which is probably the worst possible scenario.  In this case

it's better to 'do the best you can' and then continue as if nothing

happened.

The above means that one should not use MySQL to check fields content,

but one should do this in the application.

@node Portability, Internal use, Design Limitations, Optimize Overview

@subsection Portability

the columns in the table, use @code{DESCRIBE tbl_name} to find out.

@item

@cindex default values

Any column not explicitly given a value is set to its default value.  For

example, if you specify a column list that doesn't name all the columns in

the table, unnamed columns are set to their default values.  Default value

assignment is described in @ref{CREATE TABLE, , @code{CREATE TABLE}}.

MySQL always has a default value for all fields. This is something

that is imposed on MySQL to be able to work with both transactional

and not transactional tables.

Our view is that checking of fields content should be done in the

application and not in the database server.

@item

An @code{expression} may refer to any column that was set earlier in a value

list.  For example, you can say this:

value.

@item

@cindex default values

If no @code{DEFAULT} value is specified for a column, MySQL

automatically assigns one.

connection master;

reset master;

grant file on *.* to replicate@localhost identified by 'aaaaaaaaaaaaaaab';

grant file on *.* to replicate@127.0.0.1 identified by 'aaaaaaaaaaaaaaab';

connection slave;

slave start;

connection master;

** Read a string ended by '\n' into a buffer of 'max_length' size.

** Returns number of characters read, 0 on error.

** last byte is set to '\0'

** If buffer is full then to[max_length-1] will be set to \0.

*/

uint my_b_gets(IO_CACHE *info, char *to, uint max_length)

		(ulonglong) old_nr > (ulonglong) nr :

		old_nr > nr);

      /* (cmp_sign > 0 && res) || (!(cmp_sign > 0) && !res) */

      if (cmp_sign > 0 ^ !res)

      if ((cmp_sign > 0) ^ (!res))

	old_nr=nr;

    }

    result_field->set_notnull();