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union 3 and more tables
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test left only mindsdb dialect
 #333
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@ea-rus
ea-rus committed Dec 14, 2023
1 parent 17a50f4 commit cbdd192
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Showing 4 changed files with 57 additions and 32 deletions.
10 changes: 6 additions & 4 deletions mindsdb_sql/parser/dialects/mindsdb/parser.py
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Original file line number Diff line number Diff line change
Expand Up @@ -937,13 +937,15 @@ def database_engine(self, p):
return {'identifier':p.identifier, 'engine':engine, 'if_not_exists':p.if_not_exists_or_empty}

# UNION / UNION ALL
@_('select UNION select')
@_('select UNION select',
'union UNION select')
def union(self, p):
return Union(left=p.select0, right=p.select1, unique=True)
return Union(left=p[0], right=p[2], unique=True)

@_('select UNION ALL select')
@_('select UNION ALL select',
'union UNION ALL select',)
def union(self, p):
return Union(left=p.select0, right=p.select1, unique=False)
return Union(left=p[0], right=p[3], unique=False)

# tableau
@_('LPAREN select RPAREN')
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10 changes: 7 additions & 3 deletions mindsdb_sql/planner/query_planner.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1295,10 +1295,14 @@ def plan_sub_select(self, query, prev_step, add_absent_cols=False):
return prev_step

def plan_union(self, query):
query1 = self.plan_select(query.left)
query2 = self.plan_select(query.right)
if isinstance(query.left, Union):
step1 = self.plan_union(query.left)
else:
# it is select
step1 = self.plan_select(query.left)
step2 = self.plan_select(query.right)

return self.plan.add_step(UnionStep(left=query1.result, right=query2.result, unique=query.unique))
return self.plan.add_step(UnionStep(left=step1.result, right=step2.result, unique=query.unique))

# method for compatibility
def from_query(self, query=None):
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26 changes: 20 additions & 6 deletions mindsdb_sql/render/sqlalchemy_render.py
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Original file line number Diff line number Diff line change
Expand Up @@ -392,17 +392,17 @@ def prepare_select(self, node):
full=is_full
)
elif isinstance(from_table, ast.Union):
if not(isinstance(from_table.left, ast.Select) and isinstance(from_table.right, ast.Select)):
raise NotImplementedError(f'Unknown UNION {from_table.left.__name__}, {from_table.right.__name__}')

left = self.prepare_select(from_table.left)
right = self.prepare_select(from_table.right)
tables = self.extract_union_list(from_table)

alias = None
if from_table.alias:
alias = self.get_alias(from_table.alias)

table = left.union(right).subquery(alias)
table1 = tables[1]
tables_x = tables[1:]

table = table1.union(*tables_x).subquery(alias)

query = query.select_from(table)

elif isinstance(from_table, ast.Select):
Expand Down Expand Up @@ -460,6 +460,20 @@ def prepare_select(self, node):

return query

def extract_union_list(self, node):
if not (isinstance(node.left, (ast.Select, ast.Union)) and isinstance(node.right, ast.Select)):
raise NotImplementedError(
f'Unknown UNION {node.left.__class__.__name__}, {node.right.__class__.__name__}')

tables = []
if isinstance(node.left, ast.Union):
tables.extend(self.extract_union_list(node.left))
else:
tables.append(self.prepare_select(node.left))
tables.append(self.prepare_select(node.right))
return tables


def prepare_create_table(self, ast_query):
columns = []

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43 changes: 24 additions & 19 deletions tests/test_parser/test_base_sql/test_union.py
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Original file line number Diff line number Diff line change
Expand Up @@ -4,19 +4,18 @@
from mindsdb_sql.exceptions import ParsingException


@pytest.mark.parametrize('dialect', ['sqlite', 'mysql', 'mindsdb'])
class TestUnion:
def test_single_select_error(self, dialect):
def test_single_select_error(self):
sql = "SELECT col FROM tab UNION"
with pytest.raises(ParsingException):
parse_sql(sql, dialect=dialect)
parse_sql(sql)

def test_union_base(self, dialect):
def test_union_base(self):
sql = """SELECT col1 FROM tab1
UNION
SELECT col1 FROM tab2"""

ast = parse_sql(sql, dialect=dialect)
ast = parse_sql(sql)
expected_ast = Union(unique=True,
left=Select(targets=[Identifier('col1')],
from_table=Identifier(parts=['tab1']),
Expand All @@ -28,12 +27,12 @@ def test_union_base(self, dialect):
assert ast.to_tree() == expected_ast.to_tree()
assert str(ast) == str(expected_ast)

def test_union_all(self, dialect):
def test_union_all(self):
sql = """SELECT col1 FROM tab1
UNION ALL
SELECT col1 FROM tab2"""

ast = parse_sql(sql, dialect=dialect)
ast = parse_sql(sql)
expected_ast = Union(unique=False,
left=Select(targets=[Identifier('col1')],
from_table=Identifier(parts=['tab1']),
Expand All @@ -45,25 +44,31 @@ def test_union_all(self, dialect):
assert ast.to_tree() == expected_ast.to_tree()
assert str(ast) == str(expected_ast)

def test_union_alias(self, dialect):
def xtest_union_alias(self):
sql = """SELECT * FROM (
SELECT col1 FROM tab1
UNION
SELECT col1 FROM tab2
UNION
SELECT col1 FROM tab3
) AS alias"""

ast = parse_sql(sql, dialect=dialect)
ast = parse_sql(sql)
expected_ast = Select(targets=[Star()],
from_table=Union(unique=True,
alias=Identifier('alias'),
left=Select(
targets=[Identifier('col1')],
from_table=Identifier(parts=['tab1']),
),
right=Select(targets=[Identifier('col1')],
from_table=Identifier(parts=['tab2']),
),
)
from_table=Union(
unique=True,
alias=Identifier('alias'),
left=Union(
unique=True,
left=Select(
targets=[Identifier('col1')],
from_table=Identifier(parts=['tab1']),),
right=Select(targets=[Identifier('col1')],
from_table=Identifier(parts=['tab2']),),
),
right=Select(targets=[Identifier('col1')],
from_table=Identifier(parts=['tab3']),),
)
)
assert ast.to_tree() == expected_ast.to_tree()
assert str(ast) == str(expected_ast)
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