nxcals.api.extraction.data.builders.SparkSession.sql

SparkSession.sql(sqlQuery: str, args: Optional[Union[Dict[str, Any], List]] = None, **kwargs: Any) → DataFrame

Returns a DataFrame representing the result of the given query. When kwargs is specified, this method formats the given string by using the Python standard formatter. The method binds named parameters to SQL literals or positional parameters from args. It doesn’t support named and positional parameters in the same SQL query.

New in version 2.0.0.

Changed in version 3.4.0: Supports Spark Connect and parameterized SQL.

Changed in version 3.5.0: Added positional parameters.

Parameters:

  • sqlQuery (str) – SQL query string.

  • args (dict or list) –

    A dictionary of parameter names to Python objects or a list of Python objects that can be converted to SQL literal expressions. See <a href=”https://spark.apache.org/docs/latest/sql-ref-datatypes.html”> Supported Data Types</a> for supported value types in Python. For example, dictionary keys: “rank”, “name”, “birthdate”; dictionary or list values: 1, “Steven”, datetime.date(2023, 4, 2). A value can be also a Column of literal expression, in that case it is taken as is.

    New in version 3.4.0.

  • kwargs (dict) –

    Other variables that the user wants to set that can be referenced in the query

    Changed in version 3.3.0: Added optional argument kwargs to specify the mapping of variables in the query. This feature is experimental and unstable.

Return type:

DataFrame

Examples

Executing a SQL query.

>>> spark.sql("SELECT * FROM range(10) where id > 7").show()
+---+
| id|
+---+
|  8|
|  9|
+---+

Executing a SQL query with variables as Python formatter standard.

>>> spark.sql(
...     "SELECT * FROM range(10) WHERE id > {bound1} AND id < {bound2}", bound1=7, bound2=9
... ).show()
+---+
| id|
+---+
|  8|
+---+

>>> mydf = spark.range(10)
>>> spark.sql(
...     "SELECT {col} FROM {mydf} WHERE id IN {x}",
...     col=mydf.id, mydf=mydf, x=tuple(range(4))).show()
+---+
| id|
+---+
|  0|
|  1|
|  2|
|  3|
+---+

>>> spark.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=spark.createDataFrame([(1, "a"), (2, "b")], ["a", "key"]),
...   table2=spark.createDataFrame([(3, "a"), (4, "b"), (5, "b")], ["b", "key"])).show()
+---+---+
|  a|  b|
+---+---+
|  1|  3|
|  2|  4|
|  2|  5|
+---+---+

Also, it is possible to query using class:Column from DataFrame.

>>> mydf = spark.createDataFrame([(1, 4), (2, 4), (3, 6)], ["A", "B"])
>>> spark.sql("SELECT {df.A}, {df[B]} FROM {df}", df=mydf).show()
+---+---+
|  A|  B|
+---+---+
|  1|  4|
|  2|  4|
|  3|  6|
+---+---+

And substitude named parameters with the : prefix by SQL literals.

>>> spark.sql("SELECT * FROM {df} WHERE {df[B]} > :minB", {"minB" : 5}, df=mydf).show()
+---+---+
|  A|  B|
+---+---+
|  3|  6|
+---+---+

Or positional parameters marked by ? in the SQL query by SQL literals.

>>> spark.sql(
...   "SELECT * FROM {df} WHERE {df[B]} > ? and ? < {df[A]}",
...   args=[5, 2], df=mydf).show()
+---+---+
|  A|  B|
+---+---+
|  3|  6|
+---+---+