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Sep 8, 2008 · UNION removes duplicates, whereas UNION ALL does not.. In order to remove duplicates the result set must be sorted, and this may have an impact on the performance of the UNION, depending on the volume of data being sorted, and the settings of various RDBMS parameters ( For Oracle PGA_AGGREGATE_TARGET with WORKAREA_SIZE_POLICY=AUTO or SORT_AREA_SIZE and SOR_AREA_RETAINED_SIZE if WORKAREA_SIZE_POLICY=MANUAL).
Mar 20, 2017 · SELECT * FROM (SELECT colA, colB FROM tableA UNION SELECT colA, colB FROM tableB) as tableC WHERE tableC.colA > 1. If we're using a union that contains the same field name in 2 tables, then we need to give a name to the sub query as tableC (in above query). Finally, the WHERE condition should be WHERE tableC.colA > 1.
May 25, 2009 · Joins and unions can be used to combine data from one or more tables. The difference lies in how the data is combined. In simple terms, joins combine data into new columns. If two tables are joined together, then the data from the first table is shown in one set of column alongside the second table’s column in the same row. Unions combine ...
Nov 1, 2012 · 5. Best way to put condition in Query is CASE statement . you can put any number of condition in query . CASE statement is used to put conditional filters in Query . For EX. DECLARE @tmpValue. SET @tmpValue = 0 -- it will be change. SELECT * FROM Animal WHERE AniActive = 1. UNION. SELECT * FROM Animal.
First use UNION ALL for the 2 tables and join the result to Products: DECLARE @dtStart DATE = '2016-08-01'; DECLARE @dtEnd DATE = '2016-08-31'; SELECT p.Id, p.Title, SUM(t.Quantity), SUM(t.TotalAmount) AS Amount FROM ( SELECT ProductId, [TimeStamp], Quantity, TotalAmount FROM Transactions UNION ALL SELECT ProductId, [TimeStamp], Quantity, TotalAmount FROM CCTransactions ) t INNER JOIN Products p ON t.ProductId = p.Id WHERE t.[TimeStamp] >= @dtStart AND CAST(t.[TimeStamp] AS DATE) <= @dtEnd ...
Jan 11, 2018 · A union of two 1-row tables (two multiset relations each with one tuple) would have two rows (tuples) in the resulting relation. In relational algebra (which SQL isn't) the union result might be one row, though only if the two input relations contained an identical tuple, eg. self-union of a one-tuple relation. – Robert Monfera.
Mar 27, 2011 · You probably need to wrap the UNION in a sub- SELECT and apply the WHERE clause afterward: SELECT * FROM Table1 WHERE Field1 = Value1. UNION. SELECT * FROM Table2 WHERE Field1 = Value2. Basically, the UNION is looking for two complete SELECT statements to combine, and the WHERE clause is part of the SELECT statement.
Mar 18, 2013 · The ORDER BY clause is invalid in views, inline functions, derived tables, subqueries, and common table expressions, unless TOP, OFFSET or FOR XML is also specified. Simply add OFFSET 0 ROWS after ORDER BY clause: SELECT * FROM (SELECT *. FROM TABLE_A ORDER BY COLUMN_1)DUMMY_TABLE. UNION ALL. SELECT * FROM TABLE_B.
Jan 9, 2012 · The reason for this is, SQL cannot guess which values of Value to leave for you—and which to drop. That's something you need to define by yourself. That's something you need to define by yourself. Try using GROUP BY to ensure ID is not repeated, and any aggregate (here MIN , as in your example it was the minimum that survived) to select a particular value of Value :
Dec 30, 2016 · To combine data, I can use UNION ALL, but not sure about how to set up the WHILE/cursor so that the list does not need to be constantly updated. Something like. SELECT * FROM TableNamePrefix00001 UNION ALL SELECT * FROM TableNamePrefix00002 UNION ALL SELECT * FROM TableNamePrefix00003 --And so on for all tables in the list
