average

问题 SELECT *, Group_concat(rating) AS rating_total, Sum(rating_total) AS rating_sum, Avg(rating_sum) AS rating_avg FROM ratings GROUP BY pid For some reason the sum and average don't execute....how do you make this statement work? 回答1: Because of the way that SQL compiles the queries (I assume MySQL since you're using GROUP_CONCAT), you cannot reference aliased column names before the order by clause. The SUM and AVG functions are not procedural . They are done in parallel. Which means that they

问题 SELECT *, Group_concat(rating) AS rating_total, Sum(rating_total) AS rating_sum, Avg(rating_sum) AS rating_avg FROM ratings GROUP BY pid For some reason the sum and average don't execute....how do you make this statement work? 回答1: Because of the way that SQL compiles the queries (I assume MySQL since you're using GROUP_CONCAT), you cannot reference aliased column names before the order by clause. The SUM and AVG functions are not procedural . They are done in parallel. Which means that they

问题 I am dynamically plotting several points onto a google map. I'm trying to find the best way to find the center of the given points. I've tried using the following: var mapArray = new Array; mapArray[0] = new Array(42, 35.391228, -119.008401); mapArray[1] = new Array(34, 33.874277, -118.131555); mapArray[2] = new Array(214, 32.6922592, -115.4962203); mapArray[3] = new Array(216, 33.3818875, -117.2449785); mapArray[4] = new Array(40, 36.805231, -119.770192); mapArray[5] = new Array(47, 37

问题 Given the table, I am looking for a query to calculate the average score of a given question for a given teacher. If I was going to add another column to the table like SCHOOLID and wanted to have a column that calculated the average for a given question for that school, how would I do that? Thanks in advance for all of your help! 回答1: select teacherId, questionid, AVG(Score) From myTable group by teacherId, questionid 回答2: You can create a stored procedure to handle the whole requirements

问题 Let say we have TRMM precipitation data, each file represents data for each month. For example, the files in the folder are: 3B42.1998.01.01.7A.nc, 3B42.1998.02.01.7A.nc, 3B42.1998.03.01.7A.nc, 3B42.1998.04.01.7A.nc, 3B42.1998.05.01.7A.nc, ...... ...... 3B42.2010.11.01.7A.nc, 3B42.2010.12.01.7A.nc. These files having a dimension as follows : Xsize=1440, Ysize=400, Zsize=1,Tsize=1. Longitude set to 0 to 360 and Latitude set to -50 to 50. I want to calculate the amount of precipitation over a

问题 Let say we have TRMM precipitation data, each file represents data for each month. For example, the files in the folder are: 3B42.1998.01.01.7A.nc, 3B42.1998.02.01.7A.nc, 3B42.1998.03.01.7A.nc, 3B42.1998.04.01.7A.nc, 3B42.1998.05.01.7A.nc, ...... ...... 3B42.2010.11.01.7A.nc, 3B42.2010.12.01.7A.nc. These files having a dimension as follows : Xsize=1440, Ysize=400, Zsize=1,Tsize=1. Longitude set to 0 to 360 and Latitude set to -50 to 50. I want to calculate the amount of precipitation over a

问题 This question already has answers here : Closed 8 years ago . Possible Duplicate: Algorithm to determine fundamental frequency from potential harmonics If you are considering voting to close this question, please hold your horses and look at the comments first. I am back to figuring out fundamental frequency from a set of harmonics, some of which are missing. What I am doing is looking at the Gap between adjacent harmonics. I will get a set of numbers, something like: pH(1): (1,2) -> 107

问题 I am trying to update multiple columns in a row, with data from multiple columns in a subquery. The following approaches did not work for me, and I can't find different ones that suit my needs: UPDATE beers, (SELECT AVG(appearance) AS appearance, AVG(palate) AS palate, AVG(taste) AS taste, AVG(aroma) AS aroma, AVG(overall) AS overall, beer_id FROM reviews) AS review_total SET beers.appearance = review_total.appearance, beers.palate = review_total.palate, beers.taste = review_total.taste,

问题 I am writing a code in python for a project that has to accomplish a few things; 1) read in data from an xls file column by column 2) average each row of the columns in groups of three 3) then average the resulting columns I have accomplished 1 and 2 but can't quite seem to get 3, I think a lot of the trouble I'm having stems from the fact that I am using float however I need the numbers to 6 decimal places. Any help and patience is appreciated, I'm very new to python v = open("Pt_2_Test_Data

问题 I have a large data set in this format HF TLLL A T 0.999 NA 0.666 NA 0.566 NA NA 0.87 HF TLLM A T 0.500 0.500 0.666 0.566 NA NA 0.87 I want to calculate an average for each line, starting from column 5 until end of line, and ignoring the string NA . Then append the average to the end of each line. The output would look like this: HF TLLL A T 0.999 NA 0.666 NA 0.566 NA NA 0.87 0.775 HF TLLM A T 0.500 0.500 0.666 0.566 NA NA 0.87 0.620 I have been getting the sum like this, but can't figure out