![]() | ![]() | ![]() | Libmergeant Reference Manual | ![]() |
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MgQueryMgQuery — Represents any kind of DML query |
MgQuery; enum MgQueryType; guint mg_query_get_type (void); GObject* mg_query_new (MgConf *conf); GObject* mg_query_new_from_sql (MgConf *conf, const gchar *sql, GError **error); GObject* mg_query_new_copy (MgQuery *orig, GHashTable *replacements); void mg_query_set_query_type (MgQuery *query, MgQueryType type); MgQueryType mg_query_get_query_type (MgQuery *query); const gchar* mg_query_get_query_type_string (MgQuery *query); gboolean mg_query_is_select_query (MgQuery *query); gboolean mg_query_is_modif_query (MgQuery *query); MgQuery* mg_query_get_parent_query (MgQuery *query); gboolean mg_query_is_equal_to (MgQuery *query, MgQuery *compare_to); MgQfield* mg_query_get_field_by_sql_naming (MgQuery *query, const gchar *sql_naming); GSList* mg_query_get_fields_by_target (MgQuery *query, MgTarget *target, gboolean visible_fields_only); MgQfield* mg_query_get_visible_field_by_ref_field (MgQuery *query, MgTarget *target, MgField *ref_field); MgQfield* mg_query_get_any_field_by_ref_field (MgQuery *query, MgTarget *target, MgField *ref_field); void mg_query_set_sql_text (MgQuery *query, const gchar *sql, GError **error); const gchar* mg_query_get_sql_text (MgQuery *query); GSList* mg_query_get_sub_queries (MgQuery *query); void mg_query_add_sub_query (MgQuery *query, MgQuery *sub_query); void mg_query_del_sub_query (MgQuery *query, MgQuery *sub_query); const GSList* mg_query_get_param_sources (MgQuery *query); void mg_query_add_param_source (MgQuery *query, MgQuery *param_source); void mg_query_del_param_source (MgQuery *query, MgQuery *param_source); gboolean mg_query_add_target (MgQuery *query, MgTarget *target, GError **error); void mg_query_del_target (MgQuery *query, MgTarget *target); GSList* mg_query_get_targets (MgQuery *query); MgTarget* mg_query_get_target_by_xml_id (MgQuery *query, const gchar *xml_id); MgTarget* mg_query_get_target_by_alias (MgQuery *query, const gchar *alias_or_name); GSList* mg_query_get_target_pkfields (MgQuery *query, MgTarget *target); GSList* mg_query_get_joins (MgQuery *query); MgJoin* mg_query_get_join_by_targets (MgQuery *query, MgTarget *target1, MgTarget *target2); gboolean mg_query_add_join (MgQuery *query, MgJoin *join); void mg_query_del_join (MgQuery *query, MgJoin *join); void mg_query_set_condition (MgQuery *query, MgCondition *cond); MgCondition* mg_query_get_condition (MgQuery *query); GSList* mg_query_get_main_conditions (MgQuery *query); void mg_query_set_order_by_field (MgQuery *query, MgQfield *field, gint order, gboolean ascendant); gint mg_query_get_order_by_field (MgQuery *query, MgQfield *field, gboolean *ascendant); GSList* mg_query_expand_all_field (MgQuery *query, MgTarget *target); void mg_query_order_fields_using_join_conds (MgQuery *query);
"cond-serial" guint : Read "field-serial" guint : Read "really-all-fields" gpointer : Read "target-serial" guint : Read
"condition-changed" void user_function (MgQuery *mgquery, gpointer user_data); "join-added" void user_function (MgQuery *mgquery, gpointer arg1, gpointer user_data); "join-removed" void user_function (MgQuery *mgquery, gpointer arg1, gpointer user_data); "join-updated" void user_function (MgQuery *mgquery, gpointer arg1, gpointer user_data); "sub-query-added" void user_function (MgQuery *mgquery, gpointer arg1, gpointer user_data); "sub-query-removed" void user_function (MgQuery *mgquery, gpointer arg1, gpointer user_data); "sub-query-updated" void user_function (MgQuery *mgquery, gpointer arg1, gpointer user_data); "target-added" void user_function (MgQuery *mgquery, gpointer arg1, gpointer user_data); "target-removed" void user_function (MgQuery *mgquery, gpointer arg1, gpointer user_data); "target-updated" void user_function (MgQuery *mgquery, gpointer arg1, gpointer user_data); "type-changed" void user_function (MgQuery *mgquery, gpointer user_data);
Any query (which can be of any type, see the MgQueryType enum) can be represented by a MgQuery object. Also a query may require some parameters to be provided before in can be executed; each parameter is then represented by a MgParameter object, and parameters required for a query are organised within a MgContext object.
It implements the MgEntity, MgXmlStorage, MgReferer and MgRenderer interfaces.
typedef enum { MG_QUERY_TYPE_SELECT, MG_QUERY_TYPE_INSERT, MG_QUERY_TYPE_UPDATE, MG_QUERY_TYPE_DELETE, MG_QUERY_TYPE_UNION, MG_QUERY_TYPE_INTERSECT, MG_QUERY_TYPE_EXCEPT, MG_QUERY_TYPE_NON_PARSED_SQL } MgQueryType;
MG_QUERY_TYPE_SELECT | |
MG_QUERY_TYPE_INSERT | |
MG_QUERY_TYPE_UPDATE | |
MG_QUERY_TYPE_DELETE | |
MG_QUERY_TYPE_UNION | Union of SELECT queries |
MG_QUERY_TYPE_INTERSECT | Intersection of SELECT queries |
MG_QUERY_TYPE_EXCEPT | A SELECT query minus another SELECT query |
MG_QUERY_TYPE_NON_PARSED_SQL |
GObject* mg_query_new (MgConf *conf);
Creates a new MgQuery object
conf : | a MgConf object |
Returns : | the new object |
GObject* mg_query_new_from_sql (MgConf *conf, const gchar *sql, GError **error);
Creates a new MgQuery object and fills its structure by parsing the sql. If the parsing failed, then the returned query is of type MG_QUERY_TYPE_NON_PARSED_SQL.
To be parsed successfully, the expected SQL must respect the SQL standard; some extensions have been added to be able to define variables within the SQL statement. See the introduction to the MgQuery for more information.
The error is set only if the SQL statement parsing produced an error; there is always a new MgQuery object which is returned.
GObject* mg_query_new_copy (MgQuery *orig, GHashTable *replacements);
Copy constructor
orig : | a MgQuery to make a copy of |
replacements : | a hash table to store replacements, or NULL |
Returns : | a the new copy of orig |
void mg_query_set_query_type (MgQuery *query, MgQueryType type);
Sets the type of query
query : | a MgQuery object |
type : | the new type of query |
MgQueryType mg_query_get_query_type (MgQuery *query);
Get the type of a query
query : | a MgQuery object |
Returns : | the type of query |
const gchar* mg_query_get_query_type_string (MgQuery *query);
Get the type of a query as a human readable string
query : | a MgQuery object |
Returns : | a string for the type of query |
gboolean mg_query_is_select_query (MgQuery *query);
Tells if query is a SELECTION query (a simple SELECT, UNION, INTERSECT or EXCEPT); pure SQL queries are not handled and will always return FALSE.
query : | a # MgQuery object |
Returns : | TRUE if query is a selection query |
gboolean mg_query_is_modif_query (MgQuery *query);
Tells if query is a modification query (a simple UPDATE, DELETE, INSERT).; pure SQL queries are not handled and will always return FALSE.
query : | a # MgQuery object |
Returns : | TRUE if query is a modification query |
MgQuery* mg_query_get_parent_query (MgQuery *query);
Get the parent query of query
query : | a MgQuery object |
Returns : | the parent query, or NULL if query does not have any parent |
gboolean mg_query_is_equal_to (MgQuery *query, MgQuery *compare_to);
Compares query and compare_to from the point of view of the result of the execution of the two queries.
MgQfield* mg_query_get_field_by_sql_naming (MgQuery *query, const gchar *sql_naming);
query : | a MgQuery object |
sql_naming : | |
Returns : |
GSList* mg_query_get_fields_by_target (MgQuery *query, MgTarget *target, gboolean visible_fields_only);
Get a list of all the MgQfield objects in query which depent on the existance of target.
MgQfield* mg_query_get_visible_field_by_ref_field (MgQuery *query, MgTarget *target, MgField *ref_field);
Finds the first visible MgQfield object in query which represents ref_field. The returned object will be a MgQfField object which represents ref_field.
If target is specified, then the returned field will be linked to that MgTarget object.
MgQfield* mg_query_get_any_field_by_ref_field (MgQuery *query, MgTarget *target, MgField *ref_field);
Finds the first (visible or not) MgQfField object in query which represents ref_field. The returned object will be a MgQfField object which represents ref_field.
If target is specified, then the returned field will be linked to that MgTarget object.
void mg_query_set_sql_text (MgQuery *query, const gchar *sql, GError **error);
Defines query's contents from an SQL statement. The SQL text is parsed and the internal query structured is built from that; the query type is also set. If the SQL text cannot be parsed, then the internal structure of the query is emptied and the query type is set to MG_QUERY_TYPE_NON_PARSED_SQL.
To be parsed successfully, the expected SQL must respect the SQL standard; some extensions have been added to be able to define variables within the SQL statement. See the introduction to the MgQuery for more information.
query : | a # MgQuery object |
sql : | the SQL statement |
error : | location to store parsing error, or NULL |
const gchar* mg_query_get_sql_text (MgQuery *query);
Obtain a new string representing the SQL version of the query.
WARNING: the returned SQL statement may contain some extensions which allow for the definition of variables (see the introduction to the MgQuery for more information). As such the returned SQL cannot be executed as it may provoque errors. To get an executable statement, use the MgRenderer interface's methods.
query : | a MgQuery object |
Returns : | the new string |
GSList* mg_query_get_sub_queries (MgQuery *query);
Get a list of all the sub-queries managed by query
query : | a MgQuery object |
Returns : | a new list of the sub-queries |
void mg_query_add_sub_query (MgQuery *query, MgQuery *sub_query);
Add sub_query to query. Sub queries are managed by their parent query, and as such they are destroyed when their parent query is destroyed.
void mg_query_del_sub_query (MgQuery *query, MgQuery *sub_query);
Removes sub_query from query. sub_query MUST be present within query.
const GSList* mg_query_get_param_sources (MgQuery *query);
Get a list of the parameter source queries that are references as such by query.
void mg_query_add_param_source (MgQuery *query, MgQuery *param_source);
Tells query that param_source is a query which potentially will constraint the possible values of one or more of query's parameters. This implies that query keeps a reference on param_source.
void mg_query_del_param_source (MgQuery *query, MgQuery *param_source);
Tells query that it should no longer take care of param_source. The parameters which depend on param_source will still depend on it, though.
gboolean mg_query_add_target (MgQuery *query, MgTarget *target, GError **error);
Adds a target to query. A target represents a entity (it can actually be a table, a view, or another query) which query will use.
For a SELECT query, the targets appear after the FROM clause. The targets can be joined two by two using MgJoin objects
For UPDATE, DELETE or INSERT queries, there can be only ONE MgTarget object which is the one where the data modifications are performed.
For UNION and INTERSECT queries, there is no possible MgTarget object.
void mg_query_del_target (MgQuery *query, MgTarget *target);
Removes target from query. target MUST be present within query. Warning: All the joins and fields which depended on target are also removed.
GSList* mg_query_get_targets (MgQuery *query);
Get a list of all the targets used in query
query : | a MgQuery object |
Returns : | a new list of the targets |
MgTarget* mg_query_get_target_by_xml_id (MgQuery *query, const gchar *xml_id);
Get a pointer to a MgTarget (which must be within query) using its XML Id
MgTarget* mg_query_get_target_by_alias (MgQuery *query, const gchar *alias_or_name);
Get a pointer to a MgTarget (which must be within query) using its alias (if not found then alias_or_name is interpreted as the target name)
GSList* mg_query_get_target_pkfields (MgQuery *query, MgTarget *target);
Makes a list of the MgQfield objects which represent primary key fields of the entity represented by target.
If the entity represented by target does not have any primary key, or if the primary key's fields are not present in query, then the returned value is NULL.
GSList* mg_query_get_joins (MgQuery *query);
Get a list of all the joins used in query
query : | a MgQuery object |
Returns : | a new list of the joins |
MgJoin* mg_query_get_join_by_targets (MgQuery *query, MgTarget *target1, MgTarget *target2);
Find a join in query which joins the target1 and target2 targets
gboolean mg_query_add_join (MgQuery *query, MgJoin *join);
Add a join to query. A join is defined by the two MgTarget objects it joins and by a join condition which MUST ONLY make use of fields of the two entities represented by the targets.
For any given couple of MgTarget objects, there can exist ONLY ONE MgJoin which joins the two.
void mg_query_del_join (MgQuery *query, MgJoin *join);
Removes join from query. join MUST be present within query.
void mg_query_set_condition (MgQuery *query, MgCondition *cond);
Sets the query's associated condition
query : | a MgQuery object |
cond : | a MgCondition object |
MgCondition* mg_query_get_condition (MgQuery *query);
Get the query's associated condition
query : | a MgQuery object |
Returns : | the MgCondition object |
GSList* mg_query_get_main_conditions (MgQuery *query);
Makes a list of all the conditions (part of the WHERE clause) which are always verified by query when it is executed.
Examples: if the WHERE clause is: --> "A and B" then the list will contains {A, B} --> "A and (B or C)" it will contain {A, B or C} --> "A and (B and not C)", it will contain {A, B, not C}
query : | a MgQuery object |
Returns : | a new list of MgCondition objects |
void mg_query_set_order_by_field (MgQuery *query, MgQfield *field, gint order, gboolean ascendant);
Sets field to be used in the ORDER BY clause (using the order and ascendant attributes) if order >= 0. If order < 0, then field will not be used in the ORDER BY clause.
gint mg_query_get_order_by_field (MgQuery *query, MgQfield *field, gboolean *ascendant);
Tells if field (which MUST be in query) is part of the ORDER BY clause.
GSList* mg_query_expand_all_field (MgQuery *query, MgTarget *target);
Converts each visible "target.*" (MgQfAll) field into its list of fields. For example "t1.*" becomes "t1.a, t1.b" if table t1 is composed of fields "a" and "b". The original MgQfAll field is not removed, but simply rendered non visible.
The returned list must be free'd by the caller using g_slist_free().
void user_function (MgQuery *mgquery, gpointer user_data);
mgquery : | the object which received the signal. |
user_data : | user data set when the signal handler was connected. |
void user_function (MgQuery *mgquery, gpointer arg1, gpointer user_data);
mgquery : | the object which received the signal. |
arg1 : | |
user_data : | user data set when the signal handler was connected. |
void user_function (MgQuery *mgquery, gpointer arg1, gpointer user_data);
mgquery : | the object which received the signal. |
arg1 : | |
user_data : | user data set when the signal handler was connected. |
void user_function (MgQuery *mgquery, gpointer arg1, gpointer user_data);
mgquery : | the object which received the signal. |
arg1 : | |
user_data : | user data set when the signal handler was connected. |
void user_function (MgQuery *mgquery, gpointer arg1, gpointer user_data);
mgquery : | the object which received the signal. |
arg1 : | |
user_data : | user data set when the signal handler was connected. |
void user_function (MgQuery *mgquery, gpointer arg1, gpointer user_data);
mgquery : | the object which received the signal. |
arg1 : | |
user_data : | user data set when the signal handler was connected. |
void user_function (MgQuery *mgquery, gpointer arg1, gpointer user_data);
mgquery : | the object which received the signal. |
arg1 : | |
user_data : | user data set when the signal handler was connected. |
void user_function (MgQuery *mgquery, gpointer arg1, gpointer user_data);
mgquery : | the object which received the signal. |
arg1 : | |
user_data : | user data set when the signal handler was connected. |
void user_function (MgQuery *mgquery, gpointer arg1, gpointer user_data);
mgquery : | the object which received the signal. |
arg1 : | |
user_data : | user data set when the signal handler was connected. |
void user_function (MgQuery *mgquery, gpointer arg1, gpointer user_data);
mgquery : | the object which received the signal. |
arg1 : | |
user_data : | user data set when the signal handler was connected. |
void user_function (MgQuery *mgquery, gpointer user_data);
mgquery : | the object which received the signal. |
user_data : | user data set when the signal handler was connected. |
<< Objects related to queries | MgTarget >> |