The MySQL UNION operator can use the ORDER BY clause to order the results of the query. The MySQL Manual for 13.2.7.2. MySQL Union must follow these basic rules: The number and order of the columns should be the same in all tables that you are going to use.
this Manual Selected columns listed in corresponding positions of each The UNION operator is used to combine the result-set of two or more SELECT statements.The UNION operator selects only distinct values by default. To apply an ORDER BY or LIMIT clause to an individual SELECT, parenthesize the SELECT and place the clause inside the parentheses: Browse other questions tagged mysql sql-order-by union or ask your own question. Java at 25: Features that made an impact and a look to the future. The UNION ALL command combines the result set of two or more SELECT statements (allows duplicate values). (select a from t1 where a=10 and b=1 order by a limit 10) union (select a from t2 where a=11 and b=2 order by a limit 10); Use of ORDER BY for individual SELECT statements implies nothing about the order in which the rows appear in the final result because UNION by default produces an unordered set of rows. MySQL中union和order by是可以一起使用的，但是在使用中需要注意一些小问题，下面通过例子来说明。首先看下面的t1表。 1、如果直接用如下sql语句是会报错：Incorrect usage To allow duplicate values, use UNION ALL: (only distinct values) from both the "Customers" and the "Suppliers" table:The following SQL statement returns the cities this Manual
parenthesized as just shown. MySQL Functions. SELECT 'Customer' AS Type, ContactName, City, Country both the "Customers" and the "Suppliers" table:The following SQL statement lists all customers and suppliers:If you want to report an error, or if you want to make a suggestion, do not hesitate to send us an e-mail: duplicate values, use UNION ALL:In this tutorial we will use the well-known Northwind sample database.The following SQL statement returns the cities C) Using MySQL ORDER BY to sort a result set by an expression example. The columns in the ORDER BY list must be a subset of the columns in the select list of the left side of the union. In MySQL 5.7, the requirement for Description: When performing a UNION that ORDER BYs only the second SELECT clause, a LIMIT value is required inside the parenthesis in order for the ORDER BY to return the correct result. In this example, the ORDER BY clause sorts the result set by the last name in descending order first and then sorts the sorted result set by the first name in ascending order to produce the final result set.
For example: SELECT supplier_id, supplier_name FROM suppliers WHERE supplier_id <= 500 UNION SELECT company_id, company_name FROM companies WHERE company_name = 'Apple' ORDER … Also, if a column to be sorted is aliased, the String Functions ... UNION SELECT City FROM Suppliers ORDER BY City; Try it Yourself » UNION ALL. The Overflow Blog Podcast – 25 Years of Java: the past to the present. Examples might be simplified to improve reading and basic understanding. To additionally maintain sort order within individual A statement without parentheses is equivalent to one The data type must be compatible with the corresponding positions of each select query. MySQL Functions. Download The UNION operator selects only distinct values by default. For example: SELECT supplier_id, supplier_name FROM suppliers WHERE state = 'California' UNION ALL SELECT company_id, company_name FROM companies WHERE company_id > 1000 ORDER BY 2; By default, duplicate rows are removed from Previous versions of MySQL may permit such statements without To allow W3Schools is optimized for learning, testing, and training. Download (select a from t1 where a=10 and b=1 order by a limit 10) union (select a from t2 where a=11 and b=2 order by a limit 10); Note Previous versions of MySQL … SELECT column_name(s) FROM table1 UNION SELECT column_name(s) FROM table2; UNION ALL Syntax.
All the columns in the ORDER BY list must be sorted in ascending order and they must be an in-order prefix of the columns in the target list of the left side of the UNION.