derived-table

I am doing a subquery in which I have a calculated column involving random number generation. In the base query I select this column twice. MySQL 5.6 works as I expect, the calculated value being called once and fixed. The 5.7+/8.0+ execution seems to re-evaluate the subquery's column value individually for each selection. Is this correct behavior? What can I do to force it work as expected in newer versions of MySQL? CREATE TABLE t ( `id` BIGINT(20) NOT NULL PRIMARY KEY AUTO_INCREMENT ) ENGINE=InnoDB; insert into t values(); insert into t values(); insert into t values(); insert into t values

Suppose you have a query like this... SELECT T.TaskID, T.TaskName, TAU.AssignedUsers FROM `tasks` T LEFT OUTER JOIN ( SELECT TaskID, GROUP_CONCAT(U.FirstName, ' ', U.LastName SEPARATOR ', ') AS AssignedUsers FROM `tasks_assigned_users` TAU INNER JOIN `users` U ON (TAU.UserID=U.UserID) GROUP BY TaskID ) TAU ON (T.TaskID=TAU.TaskID) Multiple people can be assigned to a given task. The purpose of this query is to show one row per task, but with the people assigned to the task in a single column Now... suppose you have the proper indexes setup on tasks , users , and tasks_assigned_users . The

I need to pull column data from two tables, run calculations on the data with the result saved as an alias, and then sum those results into other alias' to display in a php table. I am trying to achieve this by creating a derived table within my SELECT statement but it doesn't work. I don't receive any errors but my table only displays the column headers. CODE: $sql = "SELECT x.company, x.stagestatus, x.shippeddate, SUM(x.totprice) as totalprice, SUM(x.sgtotquantity) as sgtotqty, SUM(x.sgtotalsqft) as sgtotsqft, SUM(x.avgsqftrev) as avgsqftrevenue, SUM(x.avgunitrev) as avgunitrevenue FROM

I want to create a new table in SQL Server with the following query. I am unable to understand why this query doesn't work. Query1: Works SELECT * FROM TABLE1 UNION SELECT * FROM TABLE2 Query2: Does not Work. Error: Msg 170, Level 15, State 1, Line 7 Line 7: Incorrect syntax near ')'. SELECT * INTO [NEW_TABLE] FROM ( SELECT * FROM TABLE1 UNION SELECT * FROM TABLE2 ) Thanks! You have to define a table alias for a derived table in SQL Server: SELECT x.* INTO [NEW_TABLE] FROM (SELECT * FROM TABLE1 UNION SELECT * FROM TABLE2) x "x" is the table alias in this example. INSERT INTO #Temp1 SELECT val1

So, its like our normal bank accounts where we have a lot of transactions which result in inflow or outflow of money. The account balance can always be derived by simply summing up the transaction values. What would be better in this case, storing the updated account balance in the database or re-calculating it whenever needed? Expected transaction volume per account: <5 daily Expected retrieval of account balance: Whenever a transaction happens and once a day on an average otherwise. How would you suggest to take a decision on this? Thanks a lot! PerformanceDBA Preface Audit requirements are