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Updated documentation

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hvlad 2008-06-09 09:29:28 +00:00
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doc/sql.extensions/README.execute_statement2
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@ -1,7 +1,7 @@
SQL Language Extension: EXECUTE STATEMENT
Extends already implemented EXECUTE STATEMENT with ability to query
external Firebird's databases.
external Firebird's databases. Introduced support for input parameters.
Authors:
Vlad Khorsun <hvlad@users.sourceforge.net>
@ -12,10 +12,20 @@ Syntax and notes :
[FOR] EXECUTE STATEMENT <query_text> [(<input_parameters>)]
[ON EXTERNAL [DATA SOURCE] <connection_string>]
[WITH AUTONOMOUS | COMMON TRANSACTION]
[AS USER <user_name>]
[PASSWORD <password>]
[WITH AUTONOMOUS | COMMON TRANSACTION]
[WITH CALLER PRIVILEGES]
[INTO <variables>]
- Order of clauses below is not fixed :
[ON EXTERNAL [DATA SOURCE] <connection_string>]
[WITH AUTONOMOUS | COMMON TRANSACTION]
[AS USER <user_name>]
[PASSWORD <password>]
[WITH CALLER PRIVILEGES]
- Duplicate clauses is not allowed
- if you use both <query_text> and <input_parameters> then you must
enclose <query_text> into round brackets, for example :
@ -24,7 +34,7 @@ Syntax and notes :
- both named and not named input parameters are supported. Mix of named and not
named input parameters in the same statement is not allowed.
- syntax of named input parameters :
- syntax of named input parameters
<input_parameters> ::=
<named_parameter>
| <input_parameters>, <named_parameter>
@ -36,38 +46,51 @@ Syntax and notes :
clashes with future boolean expressions.
This syntax may be changed in release version.
- if ON EXTERNAL DATA SOURCE clause is omitted then
a) statement will be executed against current (local) database
b) if AS USER clause is omitted or <user_name> equal to CURRENT_USER
then statement executed in current connection context
c) if <user_name> not equal to CURRENT_USER then statement executed in separate
connection established inside the same engine instance (i.e. created new internal
connection without Y-Valve and remote layers).
- <connection_string> is usual connection string accepted by isc_attach_database,
i.e. [<host_name><protocol_delimiter>]database_path.
- connection to the external data source is made using the same character set as
current (local) connection is used.
- if ON EXTERNAL DATA SOURCE is omitted then statement will be executed
within current connection.
- AUTONOMOUS TRANSACTION started new transaction with the same parameters as current
transaction. This transaction will be committed if statement executed ok or rolled
back if statement executed with errors.
- if <user_name> is omitted then CURRENT_USER is used
- COMMON TRANSACTION
a) started new transaction with the same parameters as current transaction, or
b) used already started transaction in this connection, or
c) used current transaction if current connection is used.
This transaction lifetime is bound to the lifetime of current (local) transaction
and commits\rolled back the same way as current transaction.
- if <password> is omitted then :
- by default COMMON TRANSACTION is used
- if AS USER clause is omitted then CURRENT_USER is used
- if PASSWORD clause is omitted then
a) if <user_name> is omitted, NULL or equal to CURRENT_USER value
then trusted autentication is performed, and
a1) for current connection - CURRENT_USER is effective user account
a2) for local database - CURRENT_USER is effective user account
a1) for current connection (ON EXTERNAL DATA SOURCE is omitted) -
CURRENT_USER is effective user account
a2) for local database (<connection_string> refers to the current database) -
CURRENT_USER is effective user account
a3) for remote database - operating system account under which engine
process is currently run is effective user account.
b) else only isc_dpb_user_name will be present in DPB and native autentication
is performed.
- AUTONOMOUS TRANSACTION started new transaction with the same parameters as
current transaction and this transaction is committed if statement executed ok
or rolled back if statement executed with errors.
- COMMON TRANSACTION started new transaction with the same parameters as current
transaction or used already started transaction in this connection or used
current transaction if current connection is used.
This transaction lifetime is bound to the lifetime of current (local) transaction
and its commits\rolled back the same way as current transaction.
- by default COMMON TRANSACTION is used
- if WITH CALLER PRIVILEGES is specified and ON EXTERNAL DATA SOURCE is omitted, then
statement prepared using additional privileges of caller stored procedure or trigger
(if EXECUTE STATEMENT is inside SP\trigger). This gets the same effect as if statement
is executed by SP\trigger directly.
Examples :