Implement support for functions as FROM with columns clause support

Implemented support for "table valued functions" along with additional
syntaxes supported by PostgreSQL, one of the most commonly requested
features. Table valued functions are SQL functions that return lists of
values or rows, and are prevalent in PostgreSQL in the area of JSON
functions, where the "table value" is commonly referred towards as the
"record" datatype. Table valued functions are also supported by Oracle and
SQL Server.

Moved from I5b093b72533ef695293e737eb75850b9713e5e03 due
to accidental push

Fixes: #3566
Change-Id: Iea36d04c80a5ed3509dcdd9ebf0701687143fef5

1 files changed, 13 insertions, 0 deletions

diff --git a/lib/sqlalchemy/dialects/oracle/base.py b/lib/sqlalchemy/dialects/oracle/base.py
index 6c381a2ec..9344abeee 100644
--- a/lib/sqlalchemy/dialects/oracle/base.py
+++ b/lib/sqlalchemy/dialects/oracle/base.py
@@ -924,6 +924,19 @@ class OracleCompiler(compiler.SQLCompiler):
         else:
             return ""
 
+    def visit_function(self, func, **kw):
+        text = super(OracleCompiler, self).visit_function(func, **kw)
+        if kw.get("asfrom", False):
+            text = "TABLE (%s)" % func
+        return text
+
+    def visit_table_valued_column(self, element, **kw):
+        text = super(OracleCompiler, self).visit_table_valued_column(
+            element, **kw
+        )
+        text = "COLUMN_VALUE " + text
+        return text
+
     def default_from(self):
         """Called when a ``SELECT`` statement has no froms,
         and no ``FROM`` clause is to be appended.