| GNOME Data Access manual |
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Before invoking a query you have to build the structure containing the command and you can do this with gda_command_new ().
The command type we most commonly use is GDA_COMMAND_TYPE_SQL because we will only focus on SQL queries[3]
typedef enum {
GDA_COMMAND_OPTION_IGNORE_ERRORS = 1,
GDA_COMMAND_OPTION_STOP_ON_ERRORS = 1 << 1,
GDA_COMMAND_OPTION_BAD_OPTION = 1 << 2
} GdaCommandOptions;
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Ignores all errors and executes all sentences returning data models. For failed sentences, it returns an empty data model. |
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Stops when finding and error and doesn't return data models. |
Here you see an example of creating a command:
gint
execute_sql_non_query (GdaConnection *connection, const gchar * buffer)
{
GdaCommand *command;
gint number;
command = gda_command_new (buffer, GDA_COMMAND_TYPE_SQL, GDA_COMMAND_OPTION_STOP_ON_ERRORS);
number = gda_connection_execute_non_query (connection, command, NULL);
gda_command_free (command);
return (number);
}
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Our function. You can give it several comma-separated sentences. |
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We will see it later. |
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It is a good practice to free the commands. |
Non queries are queries that does not return data, only the
number of rows affected, as a DELETE or an UPDATE. We use
gint
execute_sql_non_query (GdaConnection *connection, const gchar * buffer)
{
GdaCommand *command;
gint number;
command = gda_command_new (buffer, GDA_COMMAND_TYPE_SQL, GDA_COMMAND_OPTION_STOP_ON_ERRORS);
number = gda_connection_execute_non_query (connection, command, NULL);
gda_command_free (command);
return (number);
}
Normal queries are queries that return data (data models). You have two ways to do this:
You can use the first way when you want to invoke only a single command.
Second way is used to execute several comma-separated sentences. It is recommended
to use
gboolean
execute_sql_command (GdaConnection *connection, const gchar * buffer)
{
GdaCommand *command;
GList *list;
GList *node;
gboolean errors=FALSE;
GdaDataModel *dm;
command = gda_command_new (buffer, GDA_COMMAND_TYPE_SQL, GDA_COMMAND_OPTION_STOP_ON_ERRORS);
list = gda_connection_execute_command (connection, command, NULL);
if (list!=NULL)
for (node=g_list_first(list); node != NULL; node=g_list_next(node))
{
dm=(GdaDataModel *) node->data;
if (dm == NULL)
{
errors=TRUE;
}
else
{
show_table (dm);
g_object_unref(dm);
}
}
else
{
errors=TRUE;
}
gda_command_free (command);
return (errors);
}
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Executes the query and obtains a list of data models |
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Loop for moving through the list of data models. If you use |