I have multiple SQL queries that look similar where one uses JOIN and another LEFT OUTER JOIN. I played around with SQL and found that it the same results are returned. The codebase uses JOIN and LEFT OUTER JOIN interchangeably. While LEFT JOIN seems to be interchangeable with LEFT OUTER JOIN, I cannot I cann…
Tag: left-join
Count from 4 tables with join and null values
Tables: What I am expecting to query is this: However this is what I get: With this query: I wonder, in what way the query above could be modified to return the expected results? What would be a good approach to achieve this? Answer You are joining along two dimensions, so you are getting a Cartesian products…
SQL how to select a single value from a table with LEFT JOIN, In Google Datastudio
I have two tables one table called mailing_events and one table called mailing_outletcontact. Examples of my tables are below. The mailing table is very simple with no duplicates: My Second table “mailing_outletcontact” has duplicates in the email field. I am trying to query the database in Datast…
Performing a Union on groups of rows without the same columns. Trying to generate empty histogram bins
I am using MySQL. I have a table grades, that looks like so: I have a view that counts how many grades are in each bin, for each class using the following query. This returns: I want to add empty bins to this view, like so: So the bins increment by 5, starting at 40, and stopping at 100. My
I was asked the following pseudocode in a SQL interview based on joining condition. Can anyone explain what went went wrong with my approach?
[two tables-ta and tb with respective columns ] I was asked to put a LEFT JOIN on item id and explain what would be the possible output. I wrote a pseudocode like this- I told them the output would look like this, which they told is not the right answer. Can anyone explain what would be the correct answer alo…
SELECT COUNT from two tables is not working
I have two tables – first table is “projects”: p_id p_name 1 test1 2 test2 3 test2 4 test3 p_name is not unique The second table is “employee”: e_id jan feb mar apr may 1 2 2 3 3 4 2 1 1 3 3 2 3 1 3 2 3 3 4 4 3 2 3 4 I’d like
SQL: Use LEAD() and PARTITION BY to access to the next row following the current row
I have a mobile app browsing history dataset as shown below. DeviceDateTime: Date and Time the User views the page in the mobile app. UserID: each UserID represents a visitor who login the mobile app. PageName: There are different pages in the Mobile App. All visitors would first land on the Home page, and th…
Athena/Presto : Unnest 2 arrays with left join
So I have 2 Json arrays that need unnesting, and joining based on a key within the json structure. In theory is easy, but without having a ‘left join unnest’ functionality, it all becomes messy. I have achieved what I want, by grouping the results; but I also have concerns that it is doing 2 cross…
Adding a calculated column while joining tables in Snowflake
I have 4 tables A, B, C and D with 3 columns each A- aa, ab, ac B- ba, bb, bc C- ca, cb, cc D- da, db, dc I need to join the 4 tables and add a new calculated column (aa + ab + ac). My query …
mysql order by field row display even if empty
I’ve two tables( bom and bom_parts). Need to inner join and display stock_deduct,GRN_id,part_id fields. Table 1 (bom): Table 2 (bom_parts): MySql query: Query Result: Expected Result: Even if the part_id field is empty in this case 8, 6, I just want to display the part_id with the stock_deduct field as …