Please solve the the given Questions.Especially the 3 one is very important. 1) Please write one SQL SELECT query for each of the described results and answer the questions in b).a) The number of users per channel and registration dateb) What could happen, if the key word DISTINCT is omitted in this query?Why does the correct number of users not match with the sum of users in this result, even ifevery user had a contact, and how would you adjust the query to fix it?2) Please write one SQL SELECT query for each of the following results:a) The total pay_amount per city for sales in 2020b) The number of users, for whom the last contact has channel_name "SEM",but who have also at least one additional contact with another channelc) Per registration date and last channel, the number of users and the number of sales done byusers within 3 days after the registration3) Please write one SQL SELECT query for each of the following results:a) The number of clicks and registrations per day in 2020b) The number of clicks and registrations per click day in 2020Explain in writing: What would be measured with a) and what with b)?Please note that no physical database will be provided for the above tasks. This is due to the fact, thatany possible data set should be considered and not only a certain data sample, which is why westrongly recommend not to create a sample database for testing. In case of huge databases, specialcases are quickly overlooked when testing queries only on samples. usersPlease see on the right a DWH diagram ofan e-commerce platform.user ID integeruser city textuser gender textuser registration timestamp timestampIn the informations table you can find thesum of all online marketing advertisementimpressions (info_impressions) and clicks(info_clicks) for the respective eventtimestamps and the respective marketingchannels, through which the (potential)contactssale 0 integersale user ID integersale timestamp timestampsale type textcontact uer ID itegercontect channel0 textcontact timestamp timestampcontactin lent booleancustomers came. The table does notchannalscontain details about individualchannel ID textchannel name textcustomers.paymentsinformationsThe channels table is a lookup betweenchannel names like "SEM" or "AFF" andthe assigned alphanumerical channel IDs.D ale ID integerDy timestame timestampDY amount numericinfo channel D textinfo timestame timestampinfo cicks integerinfo impressions integerIn order to perform activities other than advertisement views and clicks, a customer (user) needs toregister on the platform, meaning to provide some personal details like address or gender. Not all ofthese details are mandatory for the registration. At the moment the customer registers on theplatform, a row is created in the users table and a user ID is assigned to the customer.All online advertisement views and clicks during a customer's lifecycle are tracked (if possible), beforeas well as after registration. The aggregates of these events are provided in the informations table, seeabove.Additionally, if applicable, at the moment of registration rows are created in the contacts table for all ofthe customer's previous advertisement clicks with the respective user ID, channel and timestamp of theclick (contact_timestamp = info_timestamp).After the registration any tracked advertisement click by the customer is also stored in the contactstable. The registration itself is not considered a contact. The contact_is_last field is always updatedaccordingly and at any point time it is true for only one row per customer.When the registered customer does a purchase on the platform, it creates a row in the sales table andwhen the item is paid, a row in the payments table.The relations between tables are defined by the names, e. g. contacts.contact_user_ID refers tousers.user_ID. A registered user does not need to have any contacts or sales.For each task below (1a to 3b) only one query is expected, which would give exactly one result set asoutput. These result sets should contain all (and only) the dimensions and aggregations mentioned inthe respective tasks. The tasks 1b and 3b also require further written explanations.Please do not create a calendar for any of the tasks, but rather use only the provided time fields in thetables. Days without results should be skipped.For the SQL queries, please choose any SQL dialect you prefer.

Question

Please solve the the given Questions.Especially the 3 one is very important. 1) Please write one SQL SELECT query for each of the described results and answer the questions in b).a) The number of users per channel and registration dateb) What could happen, if the key word DISTINCT is omitted in this query?Why does the correct number of users not match with the sum of users in this result, even ifevery user had a contact, and how would you adjust the query to fix it?2) Please write one SQL SELECT query for each of the following results:a) The total pay_amount per city for sales in 2020b) The number of users, for whom the last contact has channel_name &#34;SEM&#34;,but who have also at least one additional contact with another channelc) Per registration date and last channel, the number of users and the number of sales done byusers within 3 days after the registration3) Please write one SQL SELECT query for each of the following results:a) The number of clicks and registrations per day in 2020b) The number of clicks and registrations per click day in 2020Explain in writing: What would be measured with a) and what with b)?Please note that no physical database will be provided for the above tasks. This is due to the fact, thatany possible data set should be considered and not only a certain data sample, which is why westrongly recommend not to create a sample database for testing. In case of huge databases, specialcases are quickly overlooked when testing queries only on samples. usersPlease see on the right a DWH diagram ofan e-commerce platform.user ID integeruser city textuser gender textuser registration timestamp timestampIn the informations table you can find thesum of all online marketing advertisementimpressions (info_impressions) and clicks(info_clicks) for the respective eventtimestamps and the respective marketingchannels, through which the (potential)contactssale 0 integersale user ID integersale timestamp timestampsale type textcontact uer ID itegercontect channel0 textcontact timestamp timestampcontactin lent booleancustomers came. The table does notchannalscontain details about individualchannel ID textchannel name textcustomers.paymentsinformationsThe channels table is a lookup betweenchannel names like &#34;SEM&#34; or &#34;AFF&#34; andthe assigned alphanumerical channel IDs.D ale ID integerDy timestame timestampDY amount numericinfo channel D textinfo timestame timestampinfo cicks integerinfo impressions integerIn order to perform activities other than advertisement views and clicks, a customer (user) needs toregister on the platform, meaning to provide some personal details like address or gender. Not all ofthese details are mandatory for the registration. At the moment the customer registers on theplatform, a row is created in the users table and a user ID is assigned to the customer.All online advertisement views and clicks during a customer's lifecycle are tracked (if possible), beforeas well as after registration. The aggregates of these events are provided in the informations table, seeabove.Additionally, if applicable, at the moment of registration rows are created in the contacts table for all ofthe customer's previous advertisement clicks with the respective user ID, channel and timestamp of theclick (contact_timestamp = info_timestamp).After the registration any tracked advertisement click by the customer is also stored in the contactstable. The registration itself is not considered a contact. The contact_is_last field is always updatedaccordingly and at any point time it is true for only one row per customer.When the registered customer does a purchase on the platform, it creates a row in the sales table andwhen the item is paid, a row in the payments table.The relations between tables are defined by the names, e. g. contacts.contact_user_ID refers tousers.user_ID. A registered user does not need to have any contacts or sales.For each task below (1a to 3b) only one query is expected, which would give exactly one result set asoutput. These result sets should contain all (and only) the dimensions and aggregations mentioned inthe respective tasks. The tasks 1b and 3b also require further written explanations.Please do not create a calendar for any of the tasks, but rather use only the provided time fields in thetables. Days without results should be skipped.For the SQL queries, please choose any SQL dialect you prefer.

Accepted Answer

The following operators are used in the query in the next step:
DISTINCT is used in the SELECT…