bound parameters in UPDATE..FROM are subject to mis-ordering

[Mike Bayer]

this is a funny one:

from sqlalchemy.sql import table, column, select
from sqlalchemy.dialects import mysql

t1 = table('t1', column('x'))
t2 = table('t2', column('y'), column('z'))

subq = select([t2](t2)).where(t2.c.y == 7).alias()

stmt = t1.update().values(x=5).where(t1.c.x == subq.c.z)

compiled = stmt.compile(dialect=mysql.dialect())

# default impl, UPDATE..FROM .  y follows x
print stmt

# mysql impl, UPDATE A, B, x follows y
print compiled

# but still getting y follows x
print compiled.positiontup

that is:

UPDATE t1 SET x=:x FROM (SELECT t2.y AS y, t2.z AS z 
FROM t2 
WHERE t2.y = :y_1) AS anon_1 WHERE t1.x = anon_1.z

UPDATE t1, (SELECT t2.y AS y, t2.z AS z 
FROM t2 
WHERE t2.y = %s) AS anon_1 SET t1.x=%s WHERE t1.x = anon_1.z

[u'y_1']('x',)

[Mike Bayer]

OK very easy:

diff --git a/lib/sqlalchemy/sql/compiler.py b/lib/sqlalchemy/sql/compiler.py
index 0afcdfa..7770c7f 100644
--- a/lib/sqlalchemy/sql/compiler.py
+++ b/lib/sqlalchemy/sql/compiler.py
@@ -1606,8 +1606,6 @@ class SQLCompiler(engine.Compiled):

         extra_froms = update_stmt._extra_froms

-        colparams = self._get_colparams(update_stmt, extra_froms)
-
         text = "UPDATE "

         if update_stmt._prefixes:
@@ -1617,6 +1615,8 @@ class SQLCompiler(engine.Compiled):
         table_text = self.update_tables_clause(update_stmt, update_stmt.table,
                                                extra_froms, **kw)

+        colparams = self._get_colparams(update_stmt, extra_froms)
+
         if update_stmt._hints:
             dialect_hints = dict([
                 (table, hint_text)

more of a test:

d1 = DefaultDialect()
d1.positional = True
c1 = stmt.compile(dialect=d1)
print c1
print c1.positiontup

compiled = stmt.compile(dialect=mysql.dialect())
print compiled

print compiled.positiontup

[Mike Bayer]

9c5a13f0495c0f175b6c0fbd1124b6bedf232b2f 0.8

b1e1bf8e674f8175f33a03d master

[Mike Bayer]

Removing milestone: 0.8.xx (automated comment)