Database System Concepts
7th Edition
ISBN: 9780078022159
Author: Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Publisher: McGraw-Hill Education
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What’s the difference between the UNION and UNION ALL set operators?
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- It has to be based on this tablearrow_forwardxplain the code below in a step-by-step manner. Also explain what the two join statements intend to achieve. emp = [(1,"Smith",-1,"2018","10","M",3000), \ (2,"Rose",1,"2010","20","M",4000), \ (3,"Williams",1,"2010","10","M",1000), \ (4,"Jones",2,"2005","10","F",2000), \ ] empColumns = ["emp_id","name","superior_emp_id","year_joined", \ "emp_dept_id","gender","salary"] empDF = spark.createDataFrame(data=emp, schema = empColumns) empDF.printSchema() empDF.show(truncate=False) dept = [("Finance",10), \ ("Marketing",20), \ ("Sales",30), \ ("IT",40) \ ] deptColumns = ["dept_name","dept_id"] deptDF = spark.createDataFrame(data=dept, schema = deptColumns) deptDF.printSchema() deptDF.show(truncate=False) # Join statement 1 empDF.join(deptDF,empDF.emp_dept_id == deptDF.dept_id,"outer") \ .show(truncate=False) # Join statement 2 empDF.join(deptDF,empDF.emp_dept_id == deptDF.dept_id,"right")…arrow_forwardDefine hold time.arrow_forward
- The order of operands is significant in EXCEPT (MINUS) queries but is irrelevant in UNION queries?arrow_forwardWhich of FSK's parameters has been changed as a result of this change?arrow_forwardCountry ISO Code2 NO Name Area1 Area2 Norway 127000 14000 SY Syria 50000 21000 BD Bangladesh 15000 NULL ΤΗΝ Honduras NULL 13000 AR Argentina 317000 NULL SELECT MAX(Areal + Area2) FROM Country; Enter the result: Ex: 12345 SELECT MAX (Areal) + MAX (Area2) FROM Country; Enter the result: Ex: 12345arrow_forward
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- Where do domain restrictions begin and end?arrow_forwardThe InstantRide Driver Relationship team wants to learn how many travels each driver has done in the month of October. You need to send them the DRIVER_ID, and two calculated columns: DAY and RIDES. The DAY column is calculated using the DAY() function with the TRAVEL_START_TIME as the argument. The RIDES column is calculated by using the COUNT() function to determine the number of rides given for each day. Filter the results with the MONTH function.arrow_forwardWhich of the following statements is true about the term frequency TF? Group of answer choices It can only be calculated for 50% of documents. The calculation applies to a specific term and document. The calculation applies to a specific term only and holds for all documents. The calculation applies to a specific document only and holds for all terms.arrow_forward
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