Author:halw

Date:2008-12-07T17:38:05.000000Z


git-svn-id: https://svn.eiffel.com/eiffel-org/trunk@127 abb3cda0-5349-4a8f-a601-0c33ac3a8c38
This commit is contained in:
halw
2008-12-07 17:38:05 +00:00
parent ee8b3324fc
commit 2b2bb8f513
4 changed files with 88 additions and 67 deletions

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@@ -19,6 +19,7 @@
* Fixed missing detection of VREG and VRFT errors for labels of a named tuples which is used as an actual generic parameter of a type (fixes eweasel test#tuple012 and test#tuple013), thus some of your code might be broken since the compiler failed to check this before.
* Fixed eweasel test#valid222 where compiler properly detects VDRS-4 errors when you redefine a repeatedly inherited routine in at least one but not all branches, but fail to provide a local definition.
* Now a formal generic parameter only conforms to a formal generic parameter, that is to say assignment to a formal generic parameter where the source is of type NONE (i.e <eiffel>Void</eiffel>) will now be rejected by the compiler.
* Dropped support for older Microsoft C/C++ compilers on Windows platforms. We only support VS 2005 or greater.
==Bug fixes==

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@@ -8,19 +8,23 @@ Use the [[ref:/libraries/store/reference/db_change_flatshort|DB_CHANGE]] class
[[ref:/libraries/store/reference/db_change_flatshort|DB_CHANGE]] allows you to modify the database data using the SQL language:
* Prepare your SQL query and use modify:
<code>
modification: DB_CHANGE
-- Modification tool.
...
create modification.make
modification.modify ("Update CONTACTS set Firstname = ' John'")
modification: DB_CHANGE
-- Modification tool.
...
create modification.make
modification.modify ("Update CONTACTS set Firstname = ' John'")
</code>
* Commit your changes with your session control:
<code>
session_control: DB_CONTROL
-- Session control.
...
session_control.commit
session_control: DB_CONTROL
-- Session control.
...
session_control.commit
</code>
{{tip|It is always better to check the database status for errors before committing changes. }}

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@@ -8,11 +8,14 @@ Use the [[ref:/libraries/store/reference/db_selection_flatshort|DB_SELECTION]]
[[ref:/libraries/store/reference/db_selection_flatshort|DB_SELECTION]] enables your application to get database content using SQL 'select' queries:
* You can carry out 'select' queries in an intuitive way using directly the SQL language:
<code>
selection: DB_SELECTION
...
create selection.make
selection.set_query ("select * from CONTACTS where firstname = 'John'")
selection.execute
selection: DB_SELECTION
-- Selection tool
...
create selection.make
selection.set_query ("select * from CONTACTS where firstname = 'John'")
selection.execute
</code>
{{tip|Always check the database status for errors after your 'select' query. }}

View File

@@ -15,31 +15,36 @@ To use DB_RESULT, process in 2 steps:
[[ref:/libraries/store/reference/db_selection_flatshort|DB_SELECTION]] class provides different ways to customize result loading:
* You want to access an '''unique''' row: [[ref:/libraries/store/reference/db_result_flatshort|DB_RESULT]] object is accessible via cursor:
<code>
selection: DB_SELECTION
my_result: DB_RESULT
...
selection.query ("...")
if selection.is_ok then
selection.load_result
my_result := selection.cursor
end
selection: DB_SELECTION
my_result: DB_RESULT
...
selection.query ("...")
if selection.is_ok then
selection.load_result
my_result := selection.cursor
end
</code>
* You want to load a '''complete list''' of rows: [[ref:/libraries/store/reference/db_selection_flatshort|DB_SELECTION]] can store [[ref:/libraries/store/reference/db_result_flatshort|DB_RESULT]] objects in a list. To do this, you have mainly to provide a LIST object to DB_SELECTION with set_container:
<code>
selection: DB_SELECTION
container: ARRAYED_LIST [DB_RESULT]
create container.make (Max_results)
...
selection.set_container (container)
...
from
container.start
until
container.after
loop
...
end
selection: DB_SELECTION
container: ARRAYED_LIST [DB_RESULT]
...
create container.make (Max_results)
...
selection.set_container (container)
...
from
container.start
until
container.after
loop
...
end
</code>
{{tip|Provide [[ref:/libraries/store/reference/db_selection_flatshort|DB_SELECTION]] with the LIST structure convenient for what you need to do with the results. }}
@@ -47,34 +52,40 @@ To use DB_RESULT, process in 2 steps:
* You want to '''select part''' of the result set: you can set an action in [[ref:/libraries/store/reference/db_selection_flatshort|DB_SELECTION]] that will be executed each time a row is loaded. This action can for instance manipulate current row and define a stop condition.
** You need to define a descendant of class ACTION and set it to [[ref:/libraries/store/reference/db_selection_flatshort|DB_SELECTION]] :
<code>
class
MY_ACTION
inherit
ACTION
redefine
execute, found
end
class
MY_ACTION
inherit
ACTION
redefine
execute, found
end
...
execute
do
i := i + 1
end
...
found: BOOLEAN
do
Result := i >= Max_result
end
execute
do
i := i + 1
end
...
found: BOOLEAN
do
Result := i >= Max_result
end
</code>
** Then set action to [[ref:/libraries/store/reference/db_selection_flatshort|DB_SELECTION]] :
<code>
selection: DB_SELECTION
action: MY_ACTION
...
selection.set_action (action)
selection.query ("...")
if selection.is_ok then
selection.load_result
end
selection: DB_SELECTION
action: MY_ACTION
...
selection.set_action (action)
selection.query ("...")
if selection.is_ok then
selection.load_result
end
</code>
@@ -83,14 +94,16 @@ To use DB_RESULT, process in 2 steps:
A DB_RESULT object merely carries data retrieved from the database. You have to convert it to a DB_TUPLE to access data within the retrieved row conveniently, i.e. mostly the column values:
<code>
selection: DB_SELECTION
tuple: DB_TUPLE
...
create tuple
tuple.copy (selection.cursor)
if tuple.count >= 2 and then tuple.column_name (2).is_equal ("Firstname") then
io.putstring (tuple.item (2).out)
end
selection: DB_SELECTION
tuple: DB_TUPLE
...
create tuple
tuple.copy (selection.cursor)
if tuple.count >= 2 and then tuple.column_name (2).is_equal ("Firstname") then
io.putstring (tuple.item (2).out)
end
</code>