[tarantool-patches] Re: [PATCH v1 1/1] sql: support HAVING without GROUP BY clause

[Kirill Shcherbatov <kshcherbatov@tarantool.org>]

> db2 => SELECT SUM(a), a from t1 having sum(a) > 0
> SQL0119N  An expression starting with "A" specified in a SELECT clause, HAVING 
> clause, or ORDER BY clause is not specified in the GROUP BY clause or it is in 
> a SELECT clause, HAVING clause, or ORDER BY clause with a column function and 
> no GROUP BY clause is specified.  SQLSTATE=42803
I am able to handle this for now. 

> I would re-phrase it like:
> 
> However, it is still possible to drop GROUP BY clause in case both SELECT
> and HAVING arguments are aggregate functions
Ok, tnx.

> Nit: HAVING is rather clause, than expression. Overall, this msg looks
> a little bit weird. In Postgres it is like:
> 
> column "t1.a" must appear in the GROUP BY clause or be used in an aggregate function
> 
> So, not HAVING clause must appear, but HAVING argument.
---> HAVING argument

> Why 2.1 and not 1.5? The same for tests below.
It was totall invalid naming. I've fixed it.

==============================================================

From fd960870f3519d335ee5dc61fbdd950d297fe79c Mon Sep 17 00:00:00 2001
Message-Id: <fd960870f3519d335ee5dc61fbdd950d297fe79c.1536565618.git.kshcherbatov@tarantool.org>
From: Kirill Shcherbatov <kshcherbatov@tarantool.org>
Date: Wed, 29 Aug 2018 16:24:09 +0300
Subject: [PATCH] sql: support HAVING without GROUP BY

Allowed to use HAVING without GROUP BY when both select list
and having clause have aggregate function.

Closes 2364.

@TarantoolBot document
Title: HAVING without GROUP BY clause
A query with a HAVING clause should also have a GROUP BY clause.
Another ability is to use aggregate function both in select list
and HAVING clause.
Example:
SELECT SUM(s1) FROM te40 HAVING SUM(s1) > 0;
---
 src/box/sql/resolve.c         | 45 ++++++++++++++++----
 src/box/sql/sqliteInt.h       |  3 +-
 test/sql-tap/count.test.lua   |  8 ++--
 test/sql-tap/select3.test.lua |  2 +-
 test/sql-tap/select5.test.lua | 98 ++++++++++++++++++++++++++++++++++++++++++-
 5 files changed, 141 insertions(+), 15 deletions(-)

diff --git a/src/box/sql/resolve.c b/src/box/sql/resolve.c
index 280ecd9..c38374d 100644
--- a/src/box/sql/resolve.c
+++ b/src/box/sql/resolve.c
@@ -600,6 +600,8 @@ resolveExprStep(Walker * pWalker, Expr * pExpr)
 		/* A lone identifier is the name of a column.
 		 */
 	case TK_ID:{
+			if ((pNC->ncFlags & NC_AllowAgg) != 0)
+				pNC->ncFlags |= NC_HasUnaggregatedId;
 			return lookupName(pParse, 0, pExpr->u.zToken, pNC,
 					  pExpr);
 		}
@@ -1283,13 +1285,19 @@ resolveSelectStep(Walker * pWalker, Select * p)
 		/* Set up the local name-context to pass to sqlite3ResolveExprNames() to
 		 * resolve the result-set expression list.
 		 */
+		bool all_select_agg = true;
 		sNC.ncFlags = NC_AllowAgg;
 		sNC.pSrcList = p->pSrc;
 		sNC.pNext = pOuterNC;
-
 		/* Resolve names in the result set. */
-		if (sqlite3ResolveExprListNames(&sNC, p->pEList))
-			return WRC_Abort;
+		for (i = 0; i < p->pEList->nExpr; i++) {
+			u16 has_agg_flag = sNC.ncFlags & NC_HasAgg;
+			sNC.ncFlags &= ~NC_HasAgg;
+			if (sqlite3ResolveExprNames(&sNC, p->pEList->a[i].pExpr))
+				return WRC_Abort;
+			all_select_agg &= (sNC.ncFlags & NC_HasAgg) != 0;
+			sNC.ncFlags |= has_agg_flag;
+		}
 
 		/* If there are no aggregate functions in the result-set, and no GROUP BY
 		 * expression, do not allow aggregates in any of the other expressions.
@@ -1304,12 +1312,33 @@ resolveSelectStep(Walker * pWalker, Select * p)
 			sNC.ncFlags &= ~NC_AllowAgg;
 		}
 
-		/* If a HAVING clause is present, then there must be a GROUP BY clause.
+		/*
+		 * If a HAVING clause is present, then there must
+		 * be a GROUP BY clause or aggregate function
+		 * should be specified.
 		 */
-		if (p->pHaving && !pGroupBy) {
-			sqlite3ErrorMsg(pParse,
-					"a GROUP BY clause is required before HAVING");
-			return WRC_Abort;
+		if (p->pHaving != NULL && pGroupBy == NULL) {
+			struct NameContext having_nc;
+			memset(&having_nc, 0, sizeof(having_nc));
+			having_nc.pParse = pParse;
+			having_nc.ncFlags = NC_AllowAgg;
+			having_nc.pSrcList = p->pSrc;
+			if (all_select_agg &&
+			    sqlite3ResolveExprNames(&having_nc,
+						    p->pHaving) != 0)
+				return WRC_Abort;
+			if ((having_nc.ncFlags & NC_HasAgg) == 0 ||
+			    (having_nc.ncFlags & NC_HasUnaggregatedId) != 0) {
+				const char *err_msg =
+					tt_sprintf("HAVING argument must "
+						   "appear in the GROUP BY "
+						   "clause or be used in an "
+						   "aggregate function");
+				diag_set(ClientError, ER_SQL, err_msg);
+				pParse->nErr++;
+				pParse->rc = SQL_TARANTOOL_ERROR;
+				return WRC_Abort;
+			}
 		}
 
 		/* Add the output column list to the name-context before parsing the
diff --git a/src/box/sql/sqliteInt.h b/src/box/sql/sqliteInt.h
index abb6829..6c08fd1 100644
--- a/src/box/sql/sqliteInt.h
+++ b/src/box/sql/sqliteInt.h
@@ -2528,7 +2528,8 @@ struct NameContext {
 #define NC_IdxExpr   0x0020	/* True if resolving columns of CREATE INDEX */
 #define NC_VarSelect 0x0040	/* A correlated subquery has been seen */
 #define NC_MinMaxAgg 0x1000	/* min/max aggregates seen.  See note above */
-
+/** One or more identifiers seen without aggregate function. */
+#define NC_HasUnaggregatedId     0x2000
 /*
  * An instance of the following structure contains all information
  * needed to generate code for a single SELECT statement.
diff --git a/test/sql-tap/count.test.lua b/test/sql-tap/count.test.lua
index 45808de..700d047 100755
--- a/test/sql-tap/count.test.lua
+++ b/test/sql-tap/count.test.lua
@@ -172,15 +172,15 @@ test:do_test(
         return uses_op_count("SELECT count(*) FROM t2 WHERE a IS NOT NULL")
     end, 0)
 
-test:do_catchsql_test(
+test:do_execsql_test(
     "count-2.9",
     [[
         SELECT count(*) FROM t2 HAVING count(*)>1
-    ]], {
+    ]],
         -- <count-2.9>
-        1, "a GROUP BY clause is required before HAVING"
+        {}
         -- </count-2.9>
-    })
+    )
 
 test:do_test(
     "count-2.10",
diff --git a/test/sql-tap/select3.test.lua b/test/sql-tap/select3.test.lua
index d49bb87..c2e901e 100755
--- a/test/sql-tap/select3.test.lua
+++ b/test/sql-tap/select3.test.lua
@@ -200,7 +200,7 @@ test:do_catchsql_test("select3-3.1", [[
   SELECT log, count(*) FROM t1 HAVING log>=4
 ]], {
   -- <select3-3.1>
-  1, "a GROUP BY clause is required before HAVING"
+  1, "SQL error: HAVING argument must appear in the GROUP BY clause or be used in an aggregate function"
   -- </select3-3.1>
 })
 
diff --git a/test/sql-tap/select5.test.lua b/test/sql-tap/select5.test.lua
index 7ca25ae..d5bab1d 100755
--- a/test/sql-tap/select5.test.lua
+++ b/test/sql-tap/select5.test.lua
@@ -1,6 +1,6 @@
 #!/usr/bin/env tarantool
 test = require("sqltester")
-test:plan(32)
+test:plan(41)
 
 --!./tcltestrunner.lua
 -- 2001 September 15
@@ -412,5 +412,101 @@ test:do_execsql_test(
         -- </select5-8.8>
     })
 
+--
+-- gh-2364: Support HAVING without GROUP BY clause.
+--
+test:do_catchsql_test(
+    "select5-9.1",
+    [[
+        CREATE TABLE te40 (s1 INT, s2 INT, PRIMARY KEY (s1,s2));
+        INSERT INTO te40 VALUES (1,1);
+        INSERT INTO te40 VALUES (2,2);
+        SELECT s1 FROM te40 HAVING s1 = 1;
+    ]], {
+    -- <select5-9.1>
+    1, "SQL error: HAVING argument must appear in the GROUP BY clause or be used in an aggregate function"
+    -- <select5-9.1>
+})
+
+test:do_catchsql_test(
+    "select5-9.2",
+    [[
+        SELECT SUM(s1) FROM te40 HAVING s1 = 2;
+    ]], {
+    -- <select5-9.2>
+    1, "SQL error: HAVING argument must appear in the GROUP BY clause or be used in an aggregate function"
+    -- <select5-9.2>
+})
+
+test:do_catchsql_test(
+    "select5-9.3",
+    [[
+        SELECT s1 FROM te40 HAVING SUM(s1) = 2;
+    ]], {
+    -- <select5-9.3>
+    1, "SQL error: HAVING argument must appear in the GROUP BY clause or be used in an aggregate function"
+    -- <select5-9.3>
+})
+
+test:do_execsql_test(
+    "select5-9.4",
+    [[
+        SELECT SUM(s1) FROM te40 HAVING SUM(s1) > 0;
+    ]], {
+    -- <select5-9.4>
+    3
+    -- <select5-9.4>
+})
+
+test:do_execsql_test(
+    "select5-9.5",
+    [[
+        SELECT MIN(s1) FROM te40 HAVING SUM(s1) > 0;
+    ]], {
+    -- <select5-9.5>
+    1
+    -- <select5-9.5>
+})
+
+test:do_execsql_test(
+    "select5-9.6",
+    [[
+        SELECT SUM(s1) FROM te40 HAVING SUM(s1) < 0;
+    ]],
+    -- <select5-9.6>
+    {}
+    -- <select5-9.6>
+)
+
+test:do_catchsql_test(
+    "select5-9.7",
+    [[
+        SELECT SUM(s1),s2 FROM te40 HAVING SUM(s1) > 0;
+    ]], {
+    -- <select5-9.7>
+    1, "SQL error: HAVING argument must appear in the GROUP BY clause or be used in an aggregate function"
+    -- <select5-9.7>
+})
+
+test:do_catchsql_test(
+    "select5-9.8",
+    [[
+        SELECT SUM(s1) FROM te40 HAVING SUM(s1) > 0 and s2 > 0;
+    ]], {
+    -- <select5-9.8>
+    1, "SQL error: HAVING argument must appear in the GROUP BY clause or be used in an aggregate function"
+    -- <select5-9.8>
+})
+
+test:do_execsql_test(
+    "select5-9.9",
+    [[
+        SELECT SUM(s1) FROM te40 HAVING SUM(s1) > 0 and SUM(s2) > 0;
+    ]], {
+    -- <select5-9.9>
+    3
+    -- <select5-9.9>
+})
+
 test:finish_test()
 
-- 
2.7.4