Union all sql. UNION and UNION ALL operators works same.

Union all sql Jul 21, 2025 · UNION and UNION ALL are essential SQL tools for combining query results. In SQL, there are two primary operators for this purpose: UNION and UNION ALL. The SQL UNION Operator The UNION operator is used to combine the result-set of two or more SELECT statements. We may need to choose data from various tables and aggregate the results of all Select statements on occasion. To include duplicate values as well, the UNION ALL clause is used. Learn the difference between UNION and UNION ALL in SQL with examples, use cases, and performance considerations. Introduction to Oracle UNION operator The UNION operator is a set operator that combines the result sets of two or more SELECT statements into a single result set. Apr 18, 2019 · This article explains to the SQL Union and vs Union All operators. The UNION operator in SQL selects fields from two or more tables. There is a big difference in how these work as well as the final result set that is returned, but basically these commands join multiple datasets that have similar structures into one combined dataset. We will understand their syntax, when and why to use them, and of course, we'll illustrate everything with examples Apr 26, 2025 · UNION and UNION ALL operators in SQL are used to fetch data from two or more tables. In this guide, we will explore how to effectively use UNION and UNION ALL in your SQL queries. Only difference is UNION operator exclude duplicate rows from result set. Then it will return the content of that index. The following SQL statement returns the cities (duplicate values also) from both the "Customers" and the "Suppliers" table: Oct 1, 2025 · Discover the key differences between SQL's UNION and UNION ALL operators, their use cases, performance implications, and best practices for efficient queries. Microsoft Access UNION Query syntax of UNION versus UNION ALL to combine the results of two or more queries into a single result set with or without duplicates. Performance comparison of union vs union all and identifying the best one to use and the scenarios to use them. The SQL Union and Union All operators are used to combine the result sets from multiple SELECT statements into a single result set. The following SQL statement returns the cities (duplicate values also) from both the "Customers" and the "Suppliers" table: Sep 8, 2025 · In SQL, UNION and UNION ALL are used to combine results from multiple SELECT statements. Dec 30, 2024 · The UNION clause in SQL is a powerful tool used to combine the results of two or more SELECT statements into a single result set. UNION ALL in SQL, showing the key differences between the two using clear explanations and practical examples. Union ALL in SQL Server selects all records including duplicate If you frequently write SQL queries, you likely need to combine data from multiple tables or result sets at some point. For example, consider two tables: one listing the number of international games a player has played, and the other listing national games. The SQL Server UNION ALL operator is used to combine the result sets of 2 or more SELECT statements (does not remove duplicate rows). In the tables above, Kohli played 234 matches internationally and 234 matches nationally. Oracle UNION Operator Summary: in this tutorial, you will learn how to use the Oracle UNION operator to combine result sets returned by two or more queries. The UNION ALL operator includes all rows from each statement, including any duplicates. SQL provides the UNION, UNION ALL, and UNION DISTINCT operators to allow you […] Jul 15, 2025 · In MS SQL Server, the UNION and UNION ALL operators are used to combine the result sets of two or more SELECT statements into a single result set. Jun 23, 2017 · Ever heard about union and intersection in SQL? They're set operators that come in handy when you need to combine information from multiple tables. UNION and UNION ALL are crucial SQL operations that allow you to combine results from multiple SELECT statements. Nov 18, 2025 · Set Operators - UNION (Transact-SQL)<query_specification> | ( <query_expression> ) Is a query specification or query expression that returns data to be combined with the data from another query specification or query expression. This article explores every aspect of UNION vs UNION ALL in SQL Server for developers, DBAs, and data enthusiasts. Jun 18, 2024 · In SQL, the UNION and UNION ALL operations combine the results of two or more SELECT queries into a single result set. In this tutorial, you will learn about the SQL UNION operator with the help of examples. As you will see, understanding the subtle differences between UNION and UNION ALL functions in SQL is imperative for efficient data querying and management. When using UNION remember that the order, number, and datatype of columns should be the same in all queries. . This SQL Server tutorial explains how to use the UNION ALL operator in SQL Server (Transact-SQL) with syntax and examples. Dec 27, 2024 · We saved data in SQL tables in the relational database. May 28, 2021 · This article compares UNION vs. Jul 25, 2025 · Explore the fundamental distinctions between SQL's UNION and UNION ALL operators, including their impact on performance, duplicate handling, and data types. It is particularly useful when complete data inclusion, including duplicates is required. Oct 29, 2019 · Solution In SQL Server you have the ability to combine multiple datasets into one comprehensive dataset by using the UNION or UNION ALL operators. Step-by-step comparison of UNION vs UNION ALL. This requires additional temporary storage on the server (and may be denied to the user if there are quotas), instead of just immediately returning all results from UNION ALL The UNION ALL command combines the result set of two or more SELECT statements (allows duplicate values). You cannot use WITH in the middle of a query expression. Sep 20, 2016 · A short look at the differences in UNION and UNION ALL in a SELECT query. Remember: While SQL makes our lives easier by providing powerful tools like UNION, we must understand their mechanics fully before diving in headfirst. In this tutorial, we will go through SQL UNION Operator, its syntax, and how to use this operator in SQL statements, with the help of well detailed examples. Understanding what is the difference between UNION and UNION ALL is crucial for writing efficient and accurate SQL queries. UNION returns only unique rows, whereas UNION ALL includes all rows, keeping duplicates. The SQL UNION ALL Operator The UNION ALL operator is used to combine the result-set of two or more SELECT statements. Understanding the differences and applications of these commands is essential for any database user. Sep 24, 2023 · But watch out for some common mistakes people often make when using UNION. We'll also look at the differences between these two operators, as well as some applications. WITH is used to build up intermediate queries for use by other queries immediately after (meaning it cannot be used by multiple independent queries). When data types The UNION operator is used to combine the result-set of two or more SELECT statements. While using UNION ALL clause, ensure that column_name (s) and their data types should be in the same order across all SELECT statements. UNION and UNION ALL are powerful operators designed for this purpose—but knowing when and how to use each one effectively can impact query performance and accuracy. Nov 4, 2022 · SQL Union & Union All Operator SQL Union Operator or clause is a one of the SQL Set operators which is used to merge or combine two or more SQL Select Query results into single result set. Mar 20, 2017 · However preferring UNION ALL vs UNION will always be true, and portable SQL should avoid depending on optimizations that may not be in all databases. 5 days ago · UNION ALL is SQL’s way of combining result sets from multiple queries without worrying about duplicates. Even though the Sep 28, 2023 · In this article, we’ll discuss differences and similarities between UNION vs UNION ALL, possible use cases, and compare the performance of two set operators. Requirements for UNION ALL: Every SELECT statement within UNION ALL must have the same number of columns The columns must also have similar data types The columns in every SELECT statement Nov 17, 2025 · Your All-in-One Learning Portal: GeeksforGeeks is a comprehensive educational platform that empowers learners across domains-spanning computer science and programming, school education, upskilling, commerce, software tools, competitive exams, and more. Learn when to use each to concatenate datasets effectively, with or without duplicates. The UNION operator automatically removes duplicate rows from the result set. In this post, I want to share why understanding the difference between UNION and UNION ALL isn't just academic – it's crucial for building robust, high-performance data tools. The MySQL UNION ALL Operator The UNION ALL operator is used to combine the result-set of two or more SELECT statements. For instance, forgetting that each SELECT statement within a UNION must have matching columns can lead to errors. SQL UNION ALL combine 2 or more SELECT statements & returns single result set. The primary difference between UNION and UNION ALL lies in how they handle duplicate rows. Aug 8, 2024 · When working with SQL databases, it's common to retrieve data from multiple tables using various techniques. Whether you're aggregating records from partitions or unifying multi-system data, knowing how to use these operators effectively will make your SQL cleaner and more efficient. UNION ALL The UNION ALL command combines the result set of two or more SELECT statements (allows duplicate values). SQL UNION ALL Operator UNION ALL is an SQL operator used to combine data from multiple tables into a single result set, including all duplicate rows. The SQL UNION ALL operator is a fast and versatile tool for combining query results, preserving all rows for maximum performance. Learn how to use the UNION ALL operator to combine the result sets of two or more SELECT statements without removing duplicates. Sep 8, 2008 · The cost of UNION ALL is that the SQL engine must first create a temporary unique index for columns used as keys, and then run all subqueries to store their results in that index. UNION & UNION ALL In this lesson we'll discover how to combine the results of multiple queries using UNION, and UNION ALL. The definitions of the columns that are part of a UNION operation don't have to be the same, but they must be compatible through implicit conversion. Learn what they are and when to use each in this article. It ensures that duplicate rows are removed by default, providing only distinct values. So UNION removes duplicate rows automatically, while UNION ALL keeps everything. This allows you to retrieve data from multiple tables or views and combine it into a single dataset. Jun 10, 2025 · While UNION is a fundamental SQL command, its seemingly simple behavior hides a significant performance cost that can cripple high-volume applications. Dec 8, 2019 · SQL Server Tutorials By Pradeep Raturi - SQL UNION ALL operator is used to combine the result sets of two or more select statements . But how do you unite and merge results in SQL? This is where the UNION family of operators comes in handy. Understand the distinct contrast between SQL UNION and UNION ALL using basic examples, illustrations, and hands-on tips to prevent duplicate entries and performance errors. The syntax of the UNION ALL clause generally looks like this : Oct 1, 2024 · The SQL UNION operator combines the restults of two or more queries and makes a result set which includes fetched rows from the participating queries in the UNION. One such technique involves combining the results of two or more queries. UNION and UNION ALL operators works same. Jul 19, 2024 · In the SQL universe, the ability to combine data from multiple queries is a fundamental requirement, and SQL offers powerful functions like UNION and UNION ALL to achieve this. Learn how to combine result sets, remove duplicates, preserve duplicates, and optimize queries with examples. 1. Requirements for UNION ALL: Every SELECT statement within UNION must have the same number of columns The columns must also have similar Apr 13, 2025 · Union vs Union All – Combining data from multiple result sets is a common requirement when working with SQL Server. SQL: UNION ALL Operator This SQL tutorial explains how to use the SQL UNION ALL operator with syntax and examples. In May 13, 2023 · UNION ALL clause : UNION ALL clause is used to combine/merge the result of multiple SELECT statements into a single result by keeping duplicate rows. Sep 25, 2018 · This article provides overview of the SQL UNION operator, along with examples and explore some common questions like the differences between UNION vs UNION ALL. The UNION ALL operator does not remove duplicate rows from SELECT statement result set. We will also explore the difference between these operators along with use cases. Understanding the differences between these operations is crucial for optimizing database queries and ensuring accurate data retrieval. Learn more about these operators in SQL with this blog! Jul 18, 2024 · Understanding the differences between UNION and UNION ALL in SQL is crucial for improving your data manipulation skills, especially if you… Sep 5, 2024 · The SQL UNION and UNION ALL set operators are invaluable tools for combining query results in relational databases. This The precedence of the set operators matches the ANSI and ISO SQL standards: The UNION [ALL] and MINUS (EXCEPT) operators have equal precedence. Oct 11, 2010 · @Bob- I am using SQL Server 2008, and if i use 'union' instead of 'union all' it gives me error: Recursive common table expression 'tempData' does not contain a top-level UNION ALL operator. See the syntax, an example, and the difference with UNION and INTERSECT operators. This advanced guide will explore proper usage, syntax, performance, real-world examples, and best practices for using these operators effectively. Sep 6, 2017 · Difference between union and union all. Snowflake processes operators of equal precedence from left to right. Understanding two extremely useful SQL operators - UNION and UNION ALL. Short answer, you want the WHERE before the UNION and you want to use UNION ALL if at all possible. The UNION clause simplifies querying across multiple tables, allowing developers to merge data effectively. If you’ve used UNION before, UNION ALL is its faster, less fussy sibling that keeps every single row from all your queries, even if some rows are identical. Jul 25, 2018 · SQL - Union All Operator UNION ALL Operator is used to combine result set of two or more SELECT queries. The INTERSECT operator has higher precedence than UNION [ALL] and MINUS (EXCEPT). The SQL Union and versus Union All operators in SQL Server are explained in this article. UNION combines datasets and removes any duplicate records. This tutorial shows you how to use the SQL Server UNION to combines rows from two or more queries into a single result. Except in MySQl, the set operators UNION and UNION ALL are supported by most database platforms like DB2, Oracle, SQL server, and Postgre SQL. UNION This operation will allow you to join Oct 22, 2019 · Discover hte distinctions btween UNION and UNION ALL in SQL. Requirements for UNION: Every SELECT statement within UNION must have the same number of columns The columns must also have similar data types The columns in every SELECT statement must also be in the same This tutorial shows you how to use the SQL UNION operator to combine the result sets of two queries into a single result set. Mastering UNION and UNION ALL opens the door to easily constructing views across disparate sources. By mastering its syntax, using it with ORDER BY, joins, or subqueries, and applying it in scenarios like our logistics database, you’ll streamline data aggregation. Jan 5, 2023 · All data analysts should understand the difference between SQL UNION and SQL UNION ALL. So you probably want something like: To include duplicates, use the UNION ALL operator. From my years as a full-stack developer, few other features offer as much utility for consolidating data spread across tables. Jul 23, 2024 · The UNION ALL operator in MySQL combines the result sets of multiple SELECT statements by retaining all duplicate rows for improved performance and efficiency.