LabKey SQL hints and nits

api/src/org/labkey/api/data/dialect/BasePostgreSqlDialect.java

@@ -924,6 +924,12 @@ public boolean supportsNativeGreatestAndLeast()
         return true;
     }
 
+    @Override
+    public boolean supportsNativeIsDistinctFrom()
+    {
+        return true;
+    }
+
     @Override
     public boolean supportsIsNumeric()
     {

api/src/org/labkey/api/data/dialect/SqlDialect.java

@@ -882,6 +882,17 @@ public SQLFragment isNumericExpr(SQLFragment expression)
         throw new UnsupportedOperationException(getClass().getSimpleName() + " does not implement");
     }
 
+    /**
+     * Does the dialect natively support the standard "IS [NOT] DISTINCT FROM" predicate? PostgreSQL and Snowflake
+     * do; SQL Server, MySQL, and Oracle do not (SQL Server added GREATEST/LEAST in recent versions but has never
+     * added this predicate). Dialects that return false here get a portable CASE-based rewrite instead; see
+     * Method.IsDistinctFromMethodInfo.
+     */
+    public boolean supportsNativeIsDistinctFrom()
+    {
+        return false;
+    }
+
     public void handleCreateDatabaseException(SQLException e) throws ServletException
     {
         throw(new ServletException("Can't create database", e));

query/src/org/labkey/query/QueryTestCase.jsp

@@ -892,7 +892,7 @@ d,seven,twelve,day,month,date,duration,guid
                 assertNull(rs.getColumn(1).getFormat());
             }
         },
-        new SqlTest("SELECT 1 AS name @hidden'")
+        new SqlTest("SELECT 1 AS name @hidden")
         {
             @Override
             protected void validateResults(Results rs) throws Exception
@@ -914,18 +914,10 @@ d,seven,twelve,day,month,date,duration,guid
         },
 
         // test operators in THEN expression
-        new SqlTest("SELECT CASE WHEN 1=1 THEN 'a' || 'b' ELSE 'x' || 'y' END")
-    );
-
-    List<SqlTest> postgres = List.of(
-        // ORDER BY tests
-        new SqlTest("SELECT R.day, R.month, R.date FROM R ORDER BY R.date", 3, Rsize),
-        new SqlTest("SELECT R.day, R.month, R.date FROM R UNION SELECT R.day, R.month, R.date FROM R ORDER BY date"),
-        new SqlTest("SELECT R.guid FROM R WHERE overlaps(CAST('2001-01-01' AS DATE), CAST('2001-01-10' AS DATE), CAST('2001-01-05' AS DATE), CAST('2001-01-15' AS DATE))", 1, Rsize),
-
-        // regression test: field reference in sub-select (https://www.labkey.org/home/Developer/issues/issues-details.view?issueId=43580)
-        new SqlTest("SELECT (SELECT GROUP_CONCAT(b.displayname, ', ') FROM core.UsersAndGroups b WHERE b.email IN (SELECT UNNEST(STRING_TO_ARRAY(a.title, ',')))) AS procedurename, a.parent.rowid FROM core.containers a ", 2, 1),
+        new SqlTest("SELECT CASE WHEN 1=1 THEN 'a' || 'b' ELSE 'x' || 'y' END"),
 
+        // is_distinct_from()/is_not_distinct_from() are portable: native "IS [NOT] DISTINCT FROM" on PostgreSQL and
+        // Snowflake, a CASE-based rewrite elsewhere (e.g. SQL Server) -- see IsDistinctFromMethodInfo.getSQL()
         new MethodSqlTest("SELECT is_distinct_from(NULL,NULL)", JdbcType.BOOLEAN, false),
         new MethodSqlTest("SELECT is_not_distinct_from(NULL,NULL)", JdbcType.BOOLEAN, true),
         new MethodSqlTest("SELECT is_distinct_from(1,NULL)", JdbcType.BOOLEAN, true),
@@ -936,6 +928,16 @@ d,seven,twelve,day,month,date,duration,guid
         new MethodSqlTest("SELECT is_not_distinct_from(1,2)", JdbcType.BOOLEAN, false)
     );
 
+    List<SqlTest> postgres = List.of(
+        // ORDER BY tests
+        new SqlTest("SELECT R.day, R.month, R.date FROM R ORDER BY R.date", 3, Rsize),
+        new SqlTest("SELECT R.day, R.month, R.date FROM R UNION SELECT R.day, R.month, R.date FROM R ORDER BY date"),
+        new SqlTest("SELECT R.guid FROM R WHERE overlaps(CAST('2001-01-01' AS DATE), CAST('2001-01-10' AS DATE), CAST('2001-01-05' AS DATE), CAST('2001-01-15' AS DATE))", 1, Rsize),
+
+        // regression test: field reference in sub-select (https://www.labkey.org/home/Developer/issues/issues-details.view?issueId=43580)
+        new SqlTest("SELECT (SELECT GROUP_CONCAT(b.displayname, ', ') FROM core.UsersAndGroups b WHERE b.email IN (SELECT UNNEST(STRING_TO_ARRAY(a.title, ',')))) AS procedurename, a.parent.rowid FROM core.containers a ", 2, 1)
+    );
+
     List<SqlTest> postgresOnlyFunctions()
     {
         int majorVersion = ((BasePostgreSqlDialect) CoreSchema.getInstance().getSqlDialect()).getMajorVersion();

query/src/org/labkey/query/sql/Method.java

@@ -27,10 +27,12 @@
 import org.labkey.api.data.CompareType;
 import org.labkey.api.data.Container;
 import org.labkey.api.data.CoreSchema;
+import org.labkey.api.data.DbScope;
 import org.labkey.api.data.JdbcType;
 import org.labkey.api.data.MethodInfo;
 import org.labkey.api.data.MutableColumnInfo;
 import org.labkey.api.data.SQLFragment;
+import org.labkey.api.data.SqlSelector;
 import org.labkey.api.data.TableInfo;
 import org.labkey.api.data.dialect.SqlDialect;
 import org.labkey.api.module.Module;
@@ -167,7 +169,7 @@ public MethodInfo getMethodInfo()
         labkeyMethod.put("cos", new JdbcMethod("cos", JdbcType.DOUBLE, 1, 1));
         labkeyMethod.put("cot", new JdbcMethod("cot", JdbcType.DOUBLE, 1, 1));
         labkeyMethod.put("curdate", new JdbcMethod("curdate", JdbcType.DATE, 0, 0));
-        labkeyMethod.put("curtime", new JdbcMethod("curtime", JdbcType.DATE, 0, 0));
+        labkeyMethod.put("curtime", new JdbcMethod("curtime", JdbcType.TIME, 0, 0));
         labkeyMethod.put("dayofmonth", new JdbcMethod("dayofmonth", JdbcType.INTEGER, 1, 1));
         labkeyMethod.put("dayofweek", new JdbcMethod("dayofweek", JdbcType.INTEGER, 1, 1));
         labkeyMethod.put("dayofyear", new JdbcMethod("dayofyear", JdbcType.INTEGER, 1, 1));
@@ -214,6 +216,22 @@ public JdbcType getJdbcType(JdbcType[] args)
                 };
             }
         });
+        labkeyMethod.put("is_distinct_from", new Method(JdbcType.BOOLEAN, 2, 2)
+        {
+            @Override
+            public MethodInfo getMethodInfo()
+            {
+                return new IsDistinctFromMethodInfo(IS);
+            }
+        });
+        labkeyMethod.put("is_not_distinct_from", new Method(JdbcType.BOOLEAN, 2, 2)
+        {
+            @Override
+            public MethodInfo getMethodInfo()
+            {
+                return new IsDistinctFromMethodInfo(IS_NOT);
+            }
+        });
         labkeyMethod.put("isequal", new Method("isequal", JdbcType.BOOLEAN, 2, 2)
         {
             @Override
@@ -1843,24 +1861,6 @@ public SQLFragment getSQL(SqlDialect dialect, SQLFragment[] arguments)
         postgresMethods.put("jsonb_path_query_tz", new PassthroughMethod("jsonb_path_query_tz", JdbcType.VARCHAR, 2, 4));
         postgresMethods.put("jsonb_path_query_array_tz", new PassthroughMethod("jsonb_path_query_array_tz", JdbcType.VARCHAR, 2, 4));
         postgresMethods.put("jsonb_path_query_first_tz", new PassthroughMethod("jsonb_path_query_first_tz", JdbcType.VARCHAR, 2, 4));
-
-        // "is distinct from" and "is not distinct from" operators in method form
-        labkeyMethod.put("is_distinct_from", new Method(JdbcType.BOOLEAN, 2, 2)
-        {
-            @Override
-            public MethodInfo getMethodInfo()
-            {
-                return new IsDistinctFromMethodInfo(IS);
-            }
-        });
-        labkeyMethod.put("is_not_distinct_from", new Method(JdbcType.BOOLEAN, 2, 2)
-        {
-            @Override
-            public MethodInfo getMethodInfo()
-            {
-                return new IsDistinctFromMethodInfo(IS_NOT);
-            }
-        });
     }
 
     private static class IsDistinctFromMethodInfo extends AbstractMethodInfo
@@ -1876,13 +1876,37 @@ private static class IsDistinctFromMethodInfo extends AbstractMethodInfo
         @Override
         public SQLFragment getSQL(SqlDialect dialect, SQLFragment[] arguments)
         {
+            SQLFragment a = arguments[0];
+            SQLFragment b = arguments[1];
             SQLFragment ret = new SQLFragment();
-            ret.append(" ((").append(arguments[0]).append(")");
-            if (token == IS)
-                ret.append(" IS DISTINCT FROM ");
+
+            if (dialect.supportsNativeIsDistinctFrom())
+            {
+                ret.append(" ((").append(a).append(")");
+                if (token == IS)
+                    ret.append(" IS DISTINCT FROM ");
+                else
+                    ret.append(" IS NOT DISTINCT FROM ");
+                ret.append("(").append(b).append(")) ");
+            }
             else
-                ret.append(" IS NOT DISTINCT FROM ");
-            ret.append("(").append(arguments[1]).append(")) ");
+            {
+                // "IS [NOT] DISTINCT FROM" isn't standard/portable SQL -- it's native only on PostgreSQL-family and
+                // Snowflake dialects (and recent SQL Server). Elsewhere rewrite as a CASE expression that always
+                // evaluates to a real TRUE/FALSE -- never NULL, even when exactly one side is null -- so it behaves
+                // the same as the native predicate would.
+
+                // This is more complicated than the obvious (a=b or a is null and b is null).
+                // That expression can return NULL, we need to return only TRUE/FALSE.
+                if (token == IS)
+                    ret.append(" NOT ");
+                ret.append("(");
+                ret.append("((").append(a).append(") IS NOT NULL AND (").append(b).append(") IS NOT NULL AND (").append(a).append(")=(").append(b).append("))");
+                ret.append(" OR ");
+                ret.append("((").append(a).append(") IS NULL AND (").append(b).append(") IS NULL)");
+                ret.append(")");
+            }
+
             return ret;
         }
     }
@@ -2013,5 +2037,60 @@ public void testSimpleString()
             assertNotSimpleString(new SQLFragment("SELECT 'test'"));
             assertNotSimpleString(new SQLFragment("'test''string'"));
         }
+
+        // Exercises both the native and portable-fallback branches of IsDistinctFromMethodInfo.getSQL() against every
+        // dialect that's actually connected in this environment, not just whichever dialect the current CI leg happens
+        // to be running against. A FROM-less SELECT works everywhere except Oracle, which requires FROM DUAL.
+        //
+        // Covers both usage contexts: as a selected boolean value (where three-valued logic would otherwise leak NULL
+        // for the one-null-argument case) and as a WHERE clause filter (where three-valued logic normally treats NULL
+        // as non-matching, so this instead confirms the CASE-based rewrite still evaluates to a real TRUE/FALSE there).
+        @Test
+        public void testIsDistinctFrom()
+        {
+            record Case(String a, String b, boolean distinct) {}
+            List<Case> cases = List.of(
+                new Case("1", "2", true),
+                new Case("1", "1", false),
+                new Case("NULL", "NULL", false),
+                new Case("1", "NULL", true)
+            );
+
+            for (DbScope scope : DbScope.getDbScopesToTest())
+            {
+                SqlDialect d = scope.getSqlDialect();
+
+                for (Case c : cases)
+                {
+                    assertIsDistinctFrom(scope, d, IS, c.a(), c.b(), c.distinct());
+                    assertIsDistinctFrom(scope, d, IS_NOT, c.a(), c.b(), !c.distinct());
+                    assertIsDistinctFromWhere(scope, d, IS, c.a(), c.b(), c.distinct());
+                    assertIsDistinctFromWhere(scope, d, IS_NOT, c.a(), c.b(), !c.distinct());
+                }
+            }
+        }
+
+        private void assertIsDistinctFrom(DbScope scope, SqlDialect d, int token, String a, String b, boolean expected)
+        {
+            SQLFragment expr = new IsDistinctFromMethodInfo(token).getSQL(d, new SQLFragment[]{new SQLFragment(a), new SQLFragment(b)});
+            SQLFragment T = new SQLFragment(d.getBooleanTRUE()), F = new SQLFragment(d.getBooleanFALSE());
+            SQLFragment sql = new SQLFragment("SELECT ").append("CASE WHEN ").append(expr).append(" THEN ").append(T).append(" ELSE ").append(F).append(" END");
+            if (d.isOracle())
+                sql.append(" FROM DUAL");
+            Boolean result = new SqlSelector(scope, sql).getObject(Boolean.class);
+            assertEquals(d.getClass().getSimpleName() + ": " + sql.toDebugString(), expected, result);
+        }
+
+        private void assertIsDistinctFromWhere(DbScope scope, SqlDialect d, int token, String a, String b, boolean expected)
+        {
+            SQLFragment expr = new IsDistinctFromMethodInfo(token).getSQL(d, new SQLFragment[]{new SQLFragment(a), new SQLFragment(b)});
+            SQLFragment sql = new SQLFragment("SELECT 1");
+            if (d.isOracle())
+                sql.append(" FROM DUAL");
+            sql.append(" WHERE ").append(expr);
+
+            boolean matched = new SqlSelector(scope, sql).exists();
+            assertEquals(d.getClass().getSimpleName() + " (WHERE): " + sql.toDebugString(), expected, matched);
+        }
     }
 }

query/src/org/labkey/query/sql/QMethodCall.java

@@ -139,7 +139,9 @@ public QueryParseException fieldCheck(QNode parent, SqlDialect d)
     {
         if (getMethod(d) == null)
         {
-            return new QueryParseException("Unknown method " + getField().getName(), null, getLine(), getColumn());
+            String name = getField().getName();
+            String hint = SqlParser.forUnknownMethod(name, d);
+            return new QueryParseException("Unknown method " + name + (null == hint ? "" : ". " + hint), null, getLine(), getColumn());
         }
         return null;
     }

query/src/org/labkey/query/sql/SqlBase.g

@@ -57,9 +57,6 @@ tokens
 @lexer::header
 {
 	package org.labkey.query.sql.antlr;
-
-    import org.apache.logging.log4j.Logger;
-    import org.apache.logging.log4j.LogManager;
 }
 
 
@@ -134,17 +131,14 @@ tokens
 
 @lexer::members
 {
-    Logger _log = LogManager.getLogger(org.labkey.query.sql.SqlParser.class);
-
     protected void setPossibleID(boolean possibleID)
     {
     }
 
-    @Override
-    public void emitErrorMessage(String msg)
-    {
-        _log.debug(msg);
-    }
+    // NOTE: lexer errors are reported via reportError(), which SqlParser._SqlLexer overrides to collect
+    // them as parse errors. Always use _SqlLexer rather than instantiating SqlBaseLexer directly -- the
+    // default ANTLR emitErrorMessage() prints unmatchable input to System.err and then drops it, letting
+    // the remaining characters re-lex into a different, valid-looking query.
 }
 
 
@@ -180,6 +174,9 @@ REGR_SXY : 'regr_sxy';
 REGR_SYY : 'regr_syy';
 COUNT : 'count';
 CROSS : 'cross';
+CURRENT_DATE : 'current_date';
+CURRENT_TIME : 'current_time';
+CURRENT_TIMESTAMP : 'current_timestamp';
 DELETE : 'delete';
 DISTINCT : 'distinct';
 DOT : '.';
@@ -761,6 +758,10 @@ starAtom
 primaryExpression
 	:   ARRAY exprList ']' -> ^(METHOD_CALL IDENT["ARRAY_CONSTRUCT"] exprList)
 	|   TEXTARRAY exprList ']' -> ^(METHOD_CALL IDENT["TEXTARRAY_CONSTRUCT"] exprList)
+	// SQL-standard niladic datetime keywords -- no parens allowed; sugar for curdate()/curtime()/now()
+	|   CURRENT_DATE -> ^(METHOD_CALL IDENT["CURDATE"] ^(EXPR_LIST))
+	|   CURRENT_TIME -> ^(METHOD_CALL IDENT["CURTIME"] ^(EXPR_LIST))
+	|   CURRENT_TIMESTAMP -> ^(METHOD_CALL IDENT["NOW"] ^(EXPR_LIST))
 	|   id=identPrimary
 	|   constant
 	|   OPEN! ( expression | subQuery) CLOSE!