pg_execute [-array arrayVar] [-oid oidVar] dbHandle queryString [queryProcedure]
Specifies the name of an array variable where result tuples are stored, indexed by the field names. This is ignored if queryString is not a SELECT statement. For SELECT statements, if this option is not used, result tuples values are stored in individual variables named according to the field names in the result.
Specifies the name of a variable into which the OID from an INSERT statement will be stored.
Specifies a valid database handle.
Specifies a valid SQL query.
Optional command to execute for each result tuple of a SELECT statement.
pg_execute
submits a query to the PostgreSQL backend.
If the query is not a SELECT statement, the query is executed and the
number of tuples affected by the query is returned. If the query is an
INSERT and a single tuple is inserted, the OID of the inserted tuple is
stored in the oidVar variable if the optional -oid
argument is supplied.
If the query is a SELECT statement, the query is executed. For each tuple
in the result, the tuple field values are stored in the
arrayVar
variable,
if supplied, using the field names as the array indexes, else in variables
named by the field names, and then the optional
queryProcedure
is executed if supplied.
(Omitting the queryProcedure
probably makes sense
only if the query will return a single tuple.)
The number of tuples selected is returned.
The queryProcedure
can use the Tcl
break, continue, and
return commands, with the expected behavior.
Note that if the queryProcedure
executes
return, pg_execute
does
not return ntuples
.
pg_execute
is a newer function which provides a
superset of the features of pg_select
, and can
replace pg_exec
in many cases where access to
the result handle is not needed.
For backend-handled errors, pg_execute
will
throw a Tcl error and return two element list. The first element
is an error code such as PGRES_FATAL_ERROR, and
the second element is the backend error text. For more serious
errors, such as failure to communicate with the backend,
pg_execute
will throw a Tcl error and return
just the error message text.
In the following examples, error checking with catch has been omitted for clarity.
Insert a row and save the OID in result_oid
:
pg_execute -oid result_oid $pgconn "insert into mytable values (1)"
Print the item and value fields from each row:
pg_execute -array d $pgconn "select item, value from mytable" { puts "Item=$d(item) Value=$d(value)" }
Find the maximum and minimum values and store them in $s(max) and $s(min):
pg_execute -array s $pgconn "select max(value) as max,\ min(value) as min from mytable"
Find the maximum and minimum values and store them in $max and $min:
pg_execute $pgconn "select max(value) as max, min(value) as min from mytable"