added SQLQueries class

cdplib/db_handlers/SQLQueries.py

@@ -0,0 +1,108 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+"""
+Created on Thu Dec  5 10:26:27 2019
+
+@author: tanya
+"""
+
+import os
+import sys
+
+sys.path.append(os.getcwd())
+
+
+class SQLQueries:
+    '''
+    Summary of useful complicated sql queries
+    '''
+    def __init__(self):
+        '''
+        '''
+        from cdplib.log import Log
+
+        self._log = Log("SQLQueries")
+
+    def get_combinations(self, instances: dict, table: str, columns: list = None) -> str:
+        '''
+        Returns a query to read data corresponding to combinations of given values for given columns
+         specified in the argument instances.
+
+        :param instances: a dictionary of form {"column_name_1": [val_1, val2, val3], "column_name_2": [val]}
+        :param table: table name or subquery
+        :param columns: list of column names to read from the table
+        '''
+        from copy import deepcopy
+
+        instances = deepcopy(instances)
+
+        if len(instances) == 0:
+            return table[1:-1] # removed external paranthesis
+
+        else:
+
+            column, values = list(instances.items())[0]
+
+            instances.pop(column)
+
+            if table.startswith("(SELECT"):
+                prefix = column + "_subquery."
+                sub_query_name = " " + prefix[:-1]  # removed the dot in the end
+            else:
+                prefix = ""
+                sub_query_name = prefix
+
+            if columns is None:
+                columns_subquery = "*"
+            else:
+                columns_with_prefix = [prefix + c for c in columns]
+
+                columns_subquery = ", ".join(columns_with_prefix)
+
+            if len(values) > 1:
+                table = "(SELECT DISTINCT {0} FROM {1}{2} WHERE {3}{4} IN {5})"\
+                        .format(columns_subquery, table, sub_query_name, prefix, column, tuple(values))
+
+            else:
+                table = "(SELECT DISTINCT {0} FROM {1}{2} WHERE {3}{4} = {5})"\
+                        .format(columns_subquery, table, sub_query_name, prefix, column, values[0])
+
+            return self.get_combinations(instances, table, columns)
+
+    def get_cooccurances(self, instances: dict, table: str, columns: list = None) -> str:
+        '''
+        Returns a query to read data corresponding to cooccurances of given values for given columns
+         specified in the argument instances.
+
+        :param instances: a dictionary of form {"column_name_1": [val_11, val12, val13],
+                                                "column_name_2": [val_21, val22, val23]}
+         (all the lists in the instances need to be of the same length)
+        :param table: table name or subquery
+        :param columns: list of column names to read from the table
+        '''
+        value_length = len(list(instances.values())[0])
+
+        if not all([len(vals) == value_length for vals in instances.values()]):
+            self._log.log_and_raise_error("All the values in instances should be of the same length")
+
+        if columns is None:
+            columns_subquery = "*"
+        else:
+            columns_subquery = ", ".join(columns)
+
+        if len(instances) == 1:
+            column = list(instances.keys())[0]
+
+            values = instances[column]
+
+            where_clause = "{0} IN {1}".format(column, values)
+
+        else:
+            and_statements = [" AND ".join(["{0} = {1}".format(column, instances[column][i])
+                              for column in instances.keys()]) for i in range(value_length)]
+
+            and_statements = ["({})".format(s) for s in and_statements]
+
+            where_clause = " OR ".join(and_statements)
+
+        return "SELECT DISTINCT {0} FROM {1} WHERE {2}".format(columns_subquery, table, where_clause)

cdplib/db_handlers/__init__.py

@@ -1,2 +1,3 @@
 from .MongodbHandler import *
-from .SQLHandler import *
+from .SQLHandler import *
+from .SQLQueries import *