pyspark.pandas.sql¶

pyspark.pandas.sql(query: str, index_col: Union[str, List[str], None] = None, **kwargs: Any) → pyspark.pandas.frame.DataFrame¶

Execute a SQL query and return the result as a pandas-on-Spark DataFrame.

This function acts as a standard Python string formatter with understanding the following variable types:

pandas-on-Spark DataFrame

pandas-on-Spark Series

pandas DataFrame

pandas Series

string

Parameters

querystr

the SQL query

index_colstr or list of str, optional

Column names to be used in Spark to represent pandas-on-Spark’s index. The index name in pandas-on-Spark is ignored. By default, the index is always lost.

Note

If you want to preserve the index, explicitly use DataFrame.reset_index(), and pass it to the sql statement with index_col parameter.

For example,

>>> psdf = ps.DataFrame({"A": [1, 2, 3], "B":[4, 5, 6]}, index=['a', 'b', 'c'])
>>> new_psdf = psdf.reset_index()
>>> ps.sql("SELECT * FROM {new_psdf}", index_col="index", new_psdf=new_psdf)
... 
       A  B
index
a      1  4
b      2  5
c      3  6

For MultiIndex,

>>> psdf = ps.DataFrame(
...     {"A": [1, 2, 3], "B": [4, 5, 6]},
...     index=pd.MultiIndex.from_tuples(
...         [("a", "b"), ("c", "d"), ("e", "f")], names=["index1", "index2"]
...     ),
... )
>>> new_psdf = psdf.reset_index()
>>> ps.sql(
...     "SELECT * FROM {new_psdf}", index_col=["index1", "index2"], new_psdf=new_psdf)
... 
               A  B
index1 index2
a      b       1  4
c      d       2  5
e      f       3  6

Also note that the index name(s) should be matched to the existing name.

kwargs

other variables that the user want to set that can be referenced in the query

Returns

pandas-on-Spark DataFrame

Examples

Calling a built-in SQL function.

>>> ps.sql("SELECT * FROM range(10) where id > 7")
   id
0   8
1   9

>>> ps.sql("SELECT * FROM range(10) WHERE id > {bound1} AND id < {bound2}", bound1=7, bound2=9)
   id
0   8

>>> mydf = ps.range(10)
>>> x = tuple(range(4))
>>> ps.sql("SELECT {ser} FROM {mydf} WHERE id IN {x}", ser=mydf.id, mydf=mydf, x=x)
   id
0   0
1   1
2   2
3   3

Mixing pandas-on-Spark and pandas DataFrames in a join operation. Note that the index is dropped.

>>> ps.sql('''
...   SELECT m1.a, m2.b
...   FROM {table1} m1 INNER JOIN {table2} m2
...   ON m1.key = m2.key
...   ORDER BY m1.a, m2.b''',
...   table1=ps.DataFrame({"a": [1,2], "key": ["a", "b"]}),
...   table2=pd.DataFrame({"b": [3,4,5], "key": ["a", "b", "b"]}))
   a  b
0  1  3
1  2  4
2  2  5

Also, it is possible to query using Series.

>>> psdf = ps.DataFrame({"A": [1, 2, 3], "B":[4, 5, 6]}, index=['a', 'b', 'c'])
>>> ps.sql("SELECT {mydf.A} FROM {mydf}", mydf=psdf)
   A
0  1
1  2
2  3

pyspark.pandas.concat

pyspark.pandas.broadcast