82 lines
3.4 KiB
Python
82 lines
3.4 KiB
Python
import dbutils
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import os
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def joinTableOpener(UserQuery, workingDB):
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joinType = 0
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exitFlag=0
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if ('LEFT OUTER JOIN' in UserQuery.upper()):
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joinType = 1
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# Removing unnecessary words from command
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selLower = dbutils.inputCleaner("SELECT * FROM ", UserQuery)
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selection = dbutils.inputCleaner("select * from ", selLower)
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selection = selection.replace("inner join", "").replace("left outer join", "")
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commandWords = selection.replace(",","").split()
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# Grabbing values from commands
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table1Name = commandWords[0]
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table2Name = commandWords[2]
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comparisonOperator = dbutils.getOperand(commandWords[6])
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# Importing tables into lists
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Table_1 = []
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Table_2 = []
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Table_Join = []
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TableListNames = [Table_1, Table_2]
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ActualTableNames = [table1Name, table2Name]
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if workingDB != None:
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for x in range(0,2):
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if dbutils.tableExistenceCheck(ActualTableNames[x], workingDB):
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f = open(f'{workingDB}/{ActualTableNames[x]}.txt', 'r')
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for line in f:
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TableListNames[x].append(line) #Turning tables into list of lines
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f.close()
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else:
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print(f"Could not query table {ActualTableNames[x]} because it does not exist.")
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exitFlag=1
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else:
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print("Please specify which database to use.")
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if (exitFlag==0):
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# Finding the index of columns to search
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table1Column = Table_1[0].index(commandWords[5].split(".")[1])
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table2Column = Table_2[0].index(commandWords[7].split(".")[1])
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# Performs comparisons on given data
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def joinOperandFunction(t1, t2):
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if (comparisonOperator == 0): #Equality
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if (type(Table_2[t2].split("|")[table2Column]) is str):
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if (Table_2[t2].split("|")[table2Column] == Table_1[t1].split("|")[table1Column]):
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Table_Join.append(f'{Table_1[t1]} | {Table_2[t2]}')
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else:
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if (float(Table_2[t2].split("|")[table2Column]) == float(Table_1[t1].split("|")[table1Column])):
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Table_Join.append(f'{Table_1[t1]} | {Table_2[t2]}')
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elif (comparisonOperator == 1): #Greater than
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if (Table_2[t2].split("|")[table2Column] > Table_1[t1].split("|")[table1Column]):
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Table_Join.append(f'{Table_1[t1]} | {Table_2[t2]}')
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elif (comparisonOperator == -1): #Less than
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if (Table_2[t2].split("|")[table2Column] < Table_1[t1].split("|")[table1Column]):
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Table_Join.append(f'{Table_1[t1]} | {Table_2[t2]}')
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elif (comparisonOperator == -3): #Inequality
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if (Table_2[t2].split("|")[table2Column] != Table_1[t1].split("|")[table1Column]):
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Table_Join.append(f'{Table_1[t1]} | {Table_2[t2]}')
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# Join function. Nested for loops to iterate through tables.
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def join():
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Table_1[0] = Table_1[0].rstrip('\n')
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Table_2[0] = Table_2[0].rstrip('\n')
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Table_Join.append(f"{Table_1[0]} | {Table_2[0]}")
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for t1 in range(1, len(Table_1)):
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Table_1[t1] = Table_1[t1].rstrip("\n")
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for t2 in range(1, len(Table_2)):
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Table_2[t2] = Table_2[t2].rstrip('\n')
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joinOperandFunction(t1, t2)
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# Left outer join. If program cannot find Table 1 value in the joined Table, we add it with null info for Table 2's values.
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if (joinType == 1):
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if (Table_1[t1].split("|")[table1Column] not in Table_Join[-1].split("|")[table1Column]):
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Table_Join.append(f"{Table_1[t1]} | |")
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for myTuple in Table_Join:
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print(myTuple)
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join() |