Alternative to union in oracle

Execute each SQL separately and merge and sort the result sets within your program! Sometimes, an external sort may be faster. Those two UNION parts have TableC in common, so we can join the rest to it. I have put together an oracle query that is based on quite a few unions- it executes and the returned data appears to be correct. However, it is incredibly slow.

Is there a better option than Union All for multiple selects from the same row?

UNION statements can sometimes introduce performance penalties into your query. This post has a look at how to tune your query up! Discussion Text If I have two tables each with names, how would I select all the data from both tables, but I can not us a Union all.

I need an alternative to using a set operator but produce the same as a Union all. Hi I have to simple sets of query Qand Q both of them have the SUM function use they work just fine separately, but we want the result in single query. The union in poor performance. I am trying to get data from one row in a table into three rows in a temp table, so I can update the data based on values in a different, and I am wondering if there is a better approach than doing a UNION operation. Just define the CTE first, before the actual UNION query.

If you get duplicates, add DISTINCT to the outer query.

All set operators have equal precedence. If a SQL statement contains multiple set operators, then Oracle Database evaluates them from the left to right unless parentheses explicitly specify another order. UNION ALL SELECT product_i report_column FROM cFuel.

Being able to define not only the data type, but also the length of values in a given column. The ability to view the data under the Rules section in a perhaps more readable flattened or table-like fashion. Microsoft SQL Server Forums on Bytes. Summary: in this tutorial, you will learn how to use the Oracle UNION operator to combine result sets returned by two or more queries. Introduction to Oracle UNION operator.

The UNION operator is a set operator that combines result sets of two or more SELECT statements into a single result set. As many of you know, I strongly recommend that you avoid using RIGHT OUTER JOINs, since they make your SQL code less readable and are easily rewritten as LEFT OUTER JOINs. This is a point Oracle and other software dinosaurs will labour during pitches and negotiations, pouring fresh ladles of FUD on alternatives. The amount of work to make each datasource compliant for a Union All is negligible, so, is probably a good way of doing it.

I have a table with only two columns of same datatype varchar2. How can retrieve all the values into a single column without using UNION ? Select colfrom test union select colfrom test) works but it causes redundancy of the code especially when the two columns are formed by joining many tables. When we add the Where condition the query gets slow.

Is any other way we can perform the above query. I know that doing an union all for these queries together will solve my problem.

But, Isee that union all query performance is bad and it also makes by Java code clumsy. Another alternative would be to lock the table using the SERIALIZABLE transaction isolation level. Keywords union polygons sdo_aggr_ union sdo_aggr_ set _ union sdo_geometry examples Summary. This article presents alternate methods to using Sdo_Aggr_ Set _ Union introduced in Oracle 11g. Oracle ’s SDO _AGGR_ UNION has always had horrible performance where the set of geometry objects to be unioned is somewhat more than trivial.

SQLite SQLite is a software library that implements a self-containe serverless, zero-configuration, transactional SQL database engine. SQLite is the most widely deployed SQL. Alternatives to Oracle Database for all platforms with any license. PostgreSQL PostgreSQL is a powerful, open source object-relational database system. SELECT CREATOR, NAME, CASE TYPE WHEN ‘T’ THEN ‘TABLE’ WHEN ‘V’ THEN ‘VIEW ‘ WHEN ‘A’ THEN ‘ALIAS’ END FROM SYSIBM.

The CASE statement will translate the code in the TYPE column into the text that we desire. Learn to use Union , Intersect, and Except Clauses. The UNION , INTERSECT, and EXCEPT clauses are used to combine or exclude like rows from two or more tables.

They are useful when you need to combine the from separate queries into one single result. Scalar subqueries are a powerful enhancement to Oracle9i SQL. They allow for quick formulation of extremely complex SQL statements.

Hi Tom, Can you pls explain the diff between IN and EXISTS and NOT IN and NOT EXISTS.