This eases manipulation of query results in psql scripts.
Pavel Stehule, reviewed by Piyush Newe, Shigeru Hanada, and Tom Lane
</listitem>
</varlistentry>
+ <varlistentry>
+ <term><literal>\gset</literal> [ <replaceable class="parameter">prefix</replaceable> ]</term>
+
+ <listitem>
+ <para>
+ Sends the current query input buffer to the server and stores the
+ query's output into <application>psql</> variables (see <xref
+ linkend="APP-PSQL-variables" endterm="APP-PSQL-variables-title">).
+ The query to be executed must return exactly one row. Each column of
+ the row is stored into a separate variable, named the same as the
+ column. For example:
+<programlisting>
+=> <userinput>SELECT 'hello' AS var1, 10 AS var2</userinput>
+-> <userinput>\gset</userinput>
+=> <userinput>\echo :var1 :var2</userinput>
+hello 10
+</programlisting>
+ </para>
+ <para>
+ If you specify a <replaceable class="parameter">prefix</replaceable>,
+ that string is prepended to the query's column names to create the
+ variable names to use:
+<programlisting>
+=> <userinput>SELECT 'hello' AS var1, 10 AS var2</userinput>
+-> <userinput>\gset result_</userinput>
+=> <userinput>\echo :result_var1 :result_var2</userinput>
+hello 10
+</programlisting>
+ </para>
+ <para>
+ If a column result is NULL, the corresponding variable is unset
+ rather than being set.
+ </para>
+ <para>
+ If the query fails or does not return one row,
+ no variables are changed.
+ </para>
+ </listitem>
+ </varlistentry>
+
<varlistentry>
<term><literal>\h</literal> or <literal>\help</literal> <literal>[ <replaceable class="parameter">command</replaceable> ]</literal></term>
<listitem>
free(fname);
}
- /* \g [filename] means send query, optionally with output to file/pipe */
+ /* \g [filename] -- send query, optionally with output to file/pipe */
else if (strcmp(cmd, "g") == 0)
{
char *fname = psql_scan_slash_option(scan_state,
status = PSQL_CMD_SEND;
}
+ /* \gset [prefix] -- send query and store result into variables */
+ else if (strcmp(cmd, "gset") == 0)
+ {
+ char *prefix = psql_scan_slash_option(scan_state,
+ OT_NORMAL, NULL, false);
+
+ if (prefix)
+ pset.gset_prefix = prefix;
+ else
+ {
+ /* we must set a non-NULL prefix to trigger storing */
+ pset.gset_prefix = pg_strdup("");
+ }
+ status = PSQL_CMD_SEND;
+ }
+
/* help */
else if (strcmp(cmd, "h") == 0 || strcmp(cmd, "help") == 0)
{
if (!string)
{
psql_error("%s: pg_strdup: cannot duplicate null pointer (internal error)\n",
- pset.progname);
+ pset.progname);
exit(EXIT_FAILURE);
}
tmp = strdup(string);
}
+/*
+ * StoreQueryTuple: assuming query result is OK, save data into variables
+ *
+ * Returns true if successful, false otherwise.
+ */
+static bool
+StoreQueryTuple(const PGresult *result)
+{
+ bool success = true;
+
+ if (PQntuples(result) < 1)
+ {
+ psql_error("no rows returned for \\gset\n");
+ success = false;
+ }
+ else if (PQntuples(result) > 1)
+ {
+ psql_error("more than one row returned for \\gset\n");
+ success = false;
+ }
+ else
+ {
+ int i;
+
+ for (i = 0; i < PQnfields(result); i++)
+ {
+ char *colname = PQfname(result, i);
+ char *varname;
+ char *value;
+
+ /* concate prefix and column name */
+ varname = pg_malloc(strlen(pset.gset_prefix) + strlen(colname) + 1);
+ strcpy(varname, pset.gset_prefix);
+ strcat(varname, colname);
+
+ if (!PQgetisnull(result, 0, i))
+ value = PQgetvalue(result, 0, i);
+ else
+ {
+ /* for NULL value, unset rather than set the variable */
+ value = NULL;
+ }
+
+ if (!SetVariable(pset.vars, varname, value))
+ {
+ psql_error("could not set variable \"%s\"\n", varname);
+ free(varname);
+ success = false;
+ break;
+ }
+
+ free(varname);
+ }
+ }
+
+ return success;
+}
+
+
/*
* ProcessResult: utility function for use by SendQuery() only
*
/*
- * PrintQueryResults: print out query results as required
+ * PrintQueryResults: print out (or store) query results as required
*
* Note: Utility function for use by SendQuery() only.
*
switch (PQresultStatus(results))
{
case PGRES_TUPLES_OK:
- /* print the data ... */
- success = PrintQueryTuples(results);
+ /* store or print the data ... */
+ if (pset.gset_prefix)
+ success = StoreQueryTuple(results);
+ else
+ success = PrintQueryTuples(results);
/* if it's INSERT/UPDATE/DELETE RETURNING, also print status */
cmdstatus = PQcmdStatus(results);
if (strncmp(cmdstatus, "INSERT", 6) == 0 ||
if (on_error_rollback_warning == false && pset.sversion < 80000)
{
psql_error("The server (version %d.%d) does not support savepoints for ON_ERROR_ROLLBACK.\n",
- pset.sversion / 10000, (pset.sversion / 100) % 100);
+ pset.sversion / 10000, (pset.sversion / 100) % 100);
on_error_rollback_warning = true;
}
else
pset.gfname = NULL;
}
+ /* reset \gset trigger */
+ if (pset.gset_prefix)
+ {
+ free(pset.gset_prefix);
+ pset.gset_prefix = NULL;
+ }
+
return OK;
}
bool started_txn = false;
bool did_pager = false;
int ntuples;
+ int fetch_count;
char fetch_cmd[64];
instr_time before,
after;
*elapsed_msec += INSTR_TIME_GET_MILLISEC(after);
}
+ /*
+ * In \gset mode, we force the fetch count to be 2, so that we will throw
+ * the appropriate error if the query returns more than one row.
+ */
+ if (pset.gset_prefix)
+ fetch_count = 2;
+ else
+ fetch_count = pset.fetch_count;
+
snprintf(fetch_cmd, sizeof(fetch_cmd),
"FETCH FORWARD %d FROM _psql_cursor",
- pset.fetch_count);
+ fetch_count);
/* prepare to write output to \g argument, if any */
if (pset.gfname)
if (pset.timing)
INSTR_TIME_SET_CURRENT(before);
- /* get FETCH_COUNT tuples at a time */
+ /* get fetch_count tuples at a time */
results = PQexec(pset.db, fetch_cmd);
if (pset.timing)
break;
}
+ if (pset.gset_prefix)
+ {
+ /* StoreQueryTuple will complain if not exactly one row */
+ OK = StoreQueryTuple(results);
+ PQclear(results);
+ break;
+ }
+
ntuples = PQntuples(results);
- if (ntuples < pset.fetch_count)
+ if (ntuples < fetch_count)
{
/* this is the last result set, so allow footer decoration */
my_popt.topt.stop_table = true;
* writing things to the stream, we presume $PAGER has disappeared and
* stop bothering to pull down more data.
*/
- if (ntuples < pset.fetch_count || cancel_pressed || flush_error ||
+ if (ntuples < fetch_count || cancel_pressed || flush_error ||
ferror(pset.queryFout))
break;
}
currdb = PQdb(pset.db);
- output = PageOutput(94, pager);
+ output = PageOutput(95, pager);
/* if you add/remove a line here, change the row count above */
fprintf(output, _("General\n"));
fprintf(output, _(" \\copyright show PostgreSQL usage and distribution terms\n"));
fprintf(output, _(" \\g [FILE] or ; execute query (and send results to file or |pipe)\n"));
+ fprintf(output, _(" \\gset [PREFIX] execute query and store results in psql variables\n"));
fprintf(output, _(" \\h [NAME] help on syntax of SQL commands, * for all commands\n"));
fprintf(output, _(" \\q quit psql\n"));
fprintf(output, "\n");
currdb);
else
fprintf(output, _(" \\c[onnect] [DBNAME|- USER|- HOST|- PORT|-]\n"
- " connect to new database (currently no connection)\n")),
+ " connect to new database (currently no connection)\n"));
fprintf(output, _(" \\encoding [ENCODING] show or set client encoding\n"));
fprintf(output, _(" \\password [USERNAME] securely change the password for a user\n"));
fprintf(output, _(" \\conninfo display information about current connection\n"));
printQueryOpt popt;
char *gfname; /* one-shot file output argument for \g */
+ char *gset_prefix; /* one-shot prefix argument for \gset */
bool notty; /* stdin or stdout is not a tty (as determined
* on startup) */
"\\dF", "\\dFd", "\\dFp", "\\dFt", "\\dg", "\\di", "\\dl", "\\dL",
"\\dn", "\\do", "\\dp", "\\drds", "\\ds", "\\dS", "\\dt", "\\dT", "\\dv", "\\du",
"\\e", "\\echo", "\\ef", "\\encoding",
- "\\f", "\\g", "\\h", "\\help", "\\H", "\\i", "\\ir", "\\l",
+ "\\f", "\\g", "\\gset", "\\h", "\\help", "\\H", "\\i", "\\ir", "\\l",
"\\lo_import", "\\lo_export", "\\lo_list", "\\lo_unlink",
"\\o", "\\p", "\\password", "\\prompt", "\\pset", "\\q", "\\qecho", "\\r",
"\\set", "\\sf", "\\t", "\\T",
--- /dev/null
+--
+-- Tests for psql features that aren't closely connected to any
+-- specific server features
+--
+-- \gset
+select 10 as test01, 20 as test02, 'Hello' as test03 \gset pref01_
+\echo :pref01_test01 :pref01_test02 :pref01_test03
+10 20 Hello
+-- should fail: bad variable name
+select 10 as "bad name"
+\gset
+could not set variable "bad name"
+-- multiple backslash commands in one line
+select 1 as x, 2 as y \gset pref01_ \\ \echo :pref01_x
+1
+select 3 as x, 4 as y \gset pref01_ \echo :pref01_x \echo :pref01_y
+3
+4
+select 5 as x, 6 as y \gset pref01_ \\ \g \echo :pref01_x :pref01_y
+ x | y
+---+---
+ 5 | 6
+(1 row)
+
+5 6
+select 7 as x, 8 as y \g \gset pref01_ \echo :pref01_x :pref01_y
+ x | y
+---+---
+ 7 | 8
+(1 row)
+
+7 8
+-- NULL should unset the variable
+\set var2 xyz
+select 1 as var1, NULL as var2, 3 as var3 \gset
+\echo :var1 :var2 :var3
+1 :var2 3
+-- \gset requires just one tuple
+select 10 as test01, 20 as test02 from generate_series(1,3) \gset
+more than one row returned for \gset
+select 10 as test01, 20 as test02 from generate_series(1,0) \gset
+no rows returned for \gset
+-- \gset should work in FETCH_COUNT mode too
+\set FETCH_COUNT 1
+select 1 as x, 2 as y \gset pref01_ \\ \echo :pref01_x
+1
+select 3 as x, 4 as y \gset pref01_ \echo :pref01_x \echo :pref01_y
+3
+4
+select 10 as test01, 20 as test02 from generate_series(1,3) \gset
+more than one row returned for \gset
+select 10 as test01, 20 as test02 from generate_series(1,0) \gset
+no rows returned for \gset
+\unset FETCH_COUNT
# ----------
# Another group of parallel tests
# ----------
-test: misc alter_generic
+test: alter_generic misc psql
# rules cannot run concurrently with any test that creates a view
test: rules
test: privileges
test: security_label
test: collate
-test: misc
test: alter_generic
+test: misc
+test: psql
test: rules
test: event_trigger
test: select_views
--- /dev/null
+--
+-- Tests for psql features that aren't closely connected to any
+-- specific server features
+--
+
+-- \gset
+
+select 10 as test01, 20 as test02, 'Hello' as test03 \gset pref01_
+
+\echo :pref01_test01 :pref01_test02 :pref01_test03
+
+-- should fail: bad variable name
+select 10 as "bad name"
+\gset
+
+-- multiple backslash commands in one line
+select 1 as x, 2 as y \gset pref01_ \\ \echo :pref01_x
+select 3 as x, 4 as y \gset pref01_ \echo :pref01_x \echo :pref01_y
+select 5 as x, 6 as y \gset pref01_ \\ \g \echo :pref01_x :pref01_y
+select 7 as x, 8 as y \g \gset pref01_ \echo :pref01_x :pref01_y
+
+-- NULL should unset the variable
+\set var2 xyz
+select 1 as var1, NULL as var2, 3 as var3 \gset
+\echo :var1 :var2 :var3
+
+-- \gset requires just one tuple
+select 10 as test01, 20 as test02 from generate_series(1,3) \gset
+select 10 as test01, 20 as test02 from generate_series(1,0) \gset
+
+-- \gset should work in FETCH_COUNT mode too
+\set FETCH_COUNT 1
+
+select 1 as x, 2 as y \gset pref01_ \\ \echo :pref01_x
+select 3 as x, 4 as y \gset pref01_ \echo :pref01_x \echo :pref01_y
+select 10 as test01, 20 as test02 from generate_series(1,3) \gset
+select 10 as test01, 20 as test02 from generate_series(1,0) \gset
+
+\unset FETCH_COUNT
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