postgresql parser support distinct on, fix #4063

src/main/java/com/alibaba/druid/sql/parser/SQLExprParser.java

@@ -1125,6 +1125,16 @@ public class SQLExprParser extends SQLParser {
                     break;
                 }
                 throw new ParserException("ERROR. " + lexer.info());
+            case ON:
+                if (dbType == DbType.postgresql) {
+                    String methodName = lexer.stringVal();
+                    lexer.nextToken();
+                    if (lexer.token == Token.LPAREN) {
+                        sqlExpr = this.methodRest(new SQLIdentifierExpr(methodName), true);
+                        break;
+                    }
+                }
+                throw new ParserException("ERROR. " + lexer.info());
             default:
                 throw new ParserException("ERROR. " + lexer.info());
         }

src/test/java/com/alibaba/druid/bvt/sql/postgresql/PostgresqlResourceTest.java

@@ -48,6 +48,10 @@ public class PostgresqlResourceTest extends PGTest {
         exec_test("bvt/parser/postgresql-2.txt");
     }
 
+    public void test_3() throws Exception {
+        exec_test("bvt/parser/postgresql-3.txt");
+    }
+
     public void exec_test(String resource) throws Exception {
         System.out.println(resource);
         InputStream is = null;
@@ -59,16 +63,19 @@ public class PostgresqlResourceTest extends PGTest {
         String[] items = input.split("---------------------------");
         String sql = items[0].trim();
         String expect = items[1].trim();
+        if (expect != null) {
+            expect = expect.replaceAll("\\r\\n", "\n");
+        }
 
         PGSQLStatementParser parser = new PGSQLStatementParser(sql);
         List<SQLStatement> statementList = parser.parseStatementList();
-        SQLStatement statemen = statementList.get(0);
+        SQLStatement stmt = statementList.get(0);
         print(statementList);
 
         Assert.assertEquals(1, statementList.size());
 
         PGSchemaStatVisitor visitor = new PGSchemaStatVisitor();
-        statemen.accept(visitor);
+        stmt.accept(visitor);
 
         System.out.println(sql);
         System.out.println("Tables : " + visitor.getTables());
@@ -77,6 +84,10 @@ public class PostgresqlResourceTest extends PGTest {
 
         System.out.println();
         System.out.println();
+
+        if (expect != null && !expect.isEmpty()) {
+            assertEquals(expect, stmt.toString());
+        }
     }
 
     void mergValidate(String sql, String expect) {

src/test/resources/bvt/parser/postgresql-0.txt

@@ -9,11 +9,14 @@ WITH RECURSIVE employee_recursive(distance, employee_name, manager_name) AS (
   )
 SELECT distance, employee_name FROM employee_recursive;
 ---------------------------
-SELECT e1.last_name
-FROM employees e1
-WHERE f(CURSOR((
-	SELECT e2.hire_date
-	FROM employees e2
-	WHERE e1.employee_id = e2.manager_id
-	)), e1.hire_date) = 1
-ORDER BY last_name;
+WITH RECURSIVE employee_recursive (distance, employee_name, manager_name) AS (
+		SELECT 1, employee_name, manager_name
+		FROM employee
+		WHERE manager_name = 'Mary'
+		UNION ALL
+		SELECT er.distance + 1, e.employee_name, e.manager_name
+		FROM employee_recursive er, employee e
+		WHERE er.employee_name = e.manager_name
+	)
+SELECT distance, employee_name
+FROM employee_recursive;

src/test/resources/bvt/parser/postgresql-1.txt

@@ -8,11 +8,9 @@ aid bigint
 PARTITION BY LIST(ds);
 
 ---------------------------
-SELECT e1.last_name
-FROM employees e1
-WHERE f(CURSOR((
-	SELECT e2.hire_date
-	FROM employees e2
-	WHERE e1.employee_id = e2.manager_id
-	)), e1.hire_date) = 1
-ORDER BY last_name;
+CREATE TABLE IF NOT EXISTS test_dim_segment (
+	aid bigint,
+	segment_id bigint,
+	segment_name text,
+	ds text NOT NULL
+);

src/test/resources/bvt/parser/postgresql-2.txt

@@ -4,11 +4,7 @@ alter table ACT_RU_INTEGRATION
             references ACT_RU_EXECUTION (ID_)
         on delete cascade
 ---------------------------
-SELECT e1.last_name
-FROM employees e1
-WHERE f(CURSOR((
-	SELECT e2.hire_date
-	FROM employees e2
-	WHERE e1.employee_id = e2.manager_id
-	)), e1.hire_date) = 1
-ORDER BY last_name;
+ALTER TABLE ACT_RU_INTEGRATION
+	ADD CONSTRAINT ACT_FK_INT_EXECUTION FOREIGN KEY (EXECUTION_ID_)
+		REFERENCES ACT_RU_EXECUTION (ID_)
+		ON DELETE CASCADE

src/test/resources/bvt/parser/postgresql-3.txt

@@ -0,0 +1,8 @@
+create table s_2c3e24b36890b0d31aeca286e84c6471 as (
+    SELECT DISTINCT ON (sn) sn, num01 FROM "s_f73e29e1c9830041f1bdfa8_2c3e24b36890b0d31aeca286e84c6471"
+ );
+---------------------------
+CREATE TABLE s_2c3e24b36890b0d31aeca286e84c6471
+AS
+SELECT DISTINCT ON(sn) AS sn, num01
+FROM "s_f73e29e1c9830041f1bdfa8_2c3e24b36890b0d31aeca286e84c6471";