Common My. SQL Queries. Common My. SQL Queries. Aggregates. Aggregates and Statistics. Aggregates from bands of values. Pivot tables crosstabsData comparison. Database metadata. Foreign keys. Primary keys. Show. Date and time. Period arithmetic. Scheduling. Frequencies. Graphs and Hierarchies. Common Queries,MySQL Queries,Common SQL Queries. Find the values of a table column c1 for which there are a specified number of listed values in another column c2. Atlassian Corp. PLC Cl A. Atlassian Corp. Plc operates as an enterprise software company. Its products help large and small organizations in tracking, collaboration. Soft32, a pioneer of downloads and reviews website, delivers uptodate software, free downloads and reviews for Windows and more. Zen Income Tax return efiling software is very user friendly and provides facility of online epayment of tax Invoices and user can directly efile IT Return in xml. JOINJoin or subquery NULLs. Ordering resultsets. Relational division. 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Basic aggregation is the simplest grouping query pattern for column foo, display the count, the smallest, the largest, the sum, the average or some other statistic of column bar values. For example, the minimum bar value per foo SELECT foo, MINbar AS bar. Return the highest bar value for each foo, ordering top to bottom by that value Read the entire item. Last updated 2. 8 Aug 2. You track squash court bookings and fees. A court booking has one fee, but it has two member references, and those can be the same if one member has brought a guest. For each booking row, the fee is to be split between the two members. What query correctly aggregates fees including cases where the two members of record are the same DROP TABLE IF EXISTS bookings. CREATE TABLE bookings . NOT NULL. member. NOT NULL. member. NOT NULL. time timestamp NOT NULL. NOT NULL. INSERT INTO bookings  courtid , member. Read the entire item. Last updated 0. 9 Sep 2. Given a parent table and two child tables, a query which sums values in both child tables, grouping on a parent table column, returns sums that are exactly twice as large as they should be. In this example from the My. SQL General Discussion list DROP TABLE IF EXISTS package. Item,package. Credit,package. Item. Tax. CREATE TABLE package. Item . package. Item. ID INT. package. Item. Name CHAR2. 0. package. Item. Price DECIMAL1. INSERT INTO package. Item VALUES1,Delta Hotel,1. CREATE TABLE package. Credit . package. Credit. ID INT. package. Credit. Item. ID INT. Read the entire item. Last updated 2. 2 Feb 2. You have a table of grouped ranks. DROP TABLE IF EXISTS grps,ranks. CREATE TABLE grps grp int. INSERT INTO grps VALUES1,2,3,4. CREATE TABLE ranksgrp int,rank int. INSERT INTO ranks VALUES1, 4 ,1, 7 ,1, 9 ,2, 2 ,2, 3 ,2, 5 ,2, 6 ,2, 8 ,3, 1 ,4,1. The simplest query for group leaders is. Read the entire item. Last updated 2. 2 May 2. Find the values of a table column c. To get an overview of the values of c. SELECT. GROUPCONCATc. ORDER BY c. 2 AS C2 values. To retrieve a list of c. IN clause specifying the c. HAVING clause specifying the required number of different items in the list. SELECT c. 1. WHERE c. IN 1,2,3,4. HAVING COUNTDISTINCT c. This is easy to generalise to multiple column expressions, and a HAVING clause specifying any number of items from the IN list. Last updated 2. 2 May 2. You have an election database with tables for candidates, parties and districts. A candidate belongs to one party a district may have any number of candidates DROP TABLE IF EXISTS parties,districts,candidates. CREATE TABLE parties . NOT NULL. PRIMARY KEY party. ENGINEMy. ISAM DEFAULT CHARSETlatin. INSERT INTO parties VALUES Conservative,Liberal,Socialist,Green,Libertarian. CREATE TABLE districts . DEFAULT NULL.  ENGINEMy. ISAM DEFAULT CHARSETlatin. INSERT INTO districts VALUES Essex,Malton,Riverdale,Guelph,Halton. Read the entire item. Last updated 1. 9 Mar 2. Given this table. Read the entire item. Last updated 1. 9 Jan 2. In a good introductory tutorial on My. SQL subqueries, Jeremy Cole developed a triply nested query to retrieve the name, population, head of state, and number of official languages in countries with the most official languages. The query uses two tables from the My. SQL world database CREATE TABLE country . Code char3 NOT NULL DEFAULT  PRIMARY KEY. Name char5. 2 NOT NULL DEFAULT . Population int1. NOT NULL DEFAULT 0. Head. Of. State char6. DEFAULT NULL.  other columns . CREATE TABLE countrylanguage . Usb Driver 2.0 Windows Xp there. Country. Code char3 NOT NULL DEFAULT  PRIMARY KEY. Language char3. 0 NOT NULL DEFAULT . Is. Official enumT,F NOT NULL DEFAULT F. Read the entire item. Last updated 2. 2 May 2. To obtain part sums of a column based on specific conditions, use If or CASE, eg. Last updated 1. 6 Aug 2. When you have parent child grandchild tables, eg companies, users, actions, and your query requirement is for per parent aggregates from the child table and per child aggregates from the grandchild table, then cascading joins yield spuriously multiplied counts, and correlated subqueries fail because the second correlated subquery cannot find a visible joining column. One solution is to use derived tables. Assuming. DROP TABLE IF EXISTS companies,users,actions. CREATE TABLE companies id int, name char1. INSERT INTO COMPANIES VALUES1,abc ltd,2,xyz inc. CREATE TABLE users id INT,companyid INT. INSERT INTO users VALUES1,1,2,1,3,1,4,2,5,2. CREATE TABLE actions id INT, userid INT, date DATE. INSERT INTO actions VALUES. Read the entire item. Last updated 2. 2 May 2. Rather than list instances including repeats on one line, you want to list distinct instances and their counts. One way is to do a simple GROUP BY query and in your application layer remove the newlines from the result. Or you can do it in one step drop table if exists t. Last updated 2. 8 Jun 2. If you need a child table aggregate result for each row in a query, whats faster, putting the correlated aggregating subquery in the SELECT list, or in the FROM clauseThus, given tables stocksid, user, ticker,lastvalue and transactionsid, sid, action, qty, price, commission, and the requirement to retrieve stock values and per stock transaction counts, which of these queries will run faster N. N. select sid, count N. The first querys syntax is simpler, so its often the first choice. EXPLAIN reports that the second query requires examination of more rows than the first query does. But benchmarks with caching turned off show that the second query is much faster mainly because it executes one subquery rather than a subquery per row. If you have a choice, put the aggregating subquery in the FROM clause. Last updated 1. 0 Oct 2. Given the table authorbookauthid INT, bookid INT, what query finds the books who have authors with more than one book in the table Even one level of recursion can induce a mild trance. Escape the trance by taking the problem one step at a time. First write the query that finds the authors with multiple books. Then join an outer query to that on authorid, and have the outer query select bookid SELECT a. FROM authorbook a. SELECT authid,countbookid. FROM authorbook a. GROUP BY authid. HAVING COUNTbookid 1. AS a. 3 ON a. 1. authida. Last updated 2. 2 May 2. A superstore is running a promotion each day, every fifth a customer wins a prize. Each day youre given a text file with data columns for customer. ID, timestamp and order amount. How do you find every fifth customer Load the data into a table, then write the query inside out with this kind of problem, nested queries are a boon. Using Load Data Infile, load the text file into a table indexless for speed named tbl with columns for customer. ID, timestamp and amount, and index the table on customer. ID, timestamp. 2.