Can Group Functions Be Mixed with Non-group Selection Fields

Q

Can Group Functions Be Mixed with Non-group Selection Fields? - MySQL FAQs - SQL SELECT Query Statements with GROUP BY

✍: FYIcenter.com

A

If a group function is used in the SELECT clause, all other selection fields must be group level fields. Non-group fields can not be mixed with group fields in the SELECT clause. The script below gives you an example of invalid SELECT statements with group and non-group selection fields:

mysql> SELECT COUNT(*), url FROM fyi_links;
ERROR 1140 (42000): Mixing of GROUP columns 
   (MIN(),MAX(),COUNT(),...) with no GROUP columns
   is illegal if there is no GROUP BY clause

In this example, COUNT(*) is a group field and "url" is a non-group field.

2007-05-11, 5896👍, 0💬

How To Apply Filtering Criteria at Group Level
How To Apply Filtering Criteria at Group Level? - MySQL FAQs - SQL SELECT Query Statements with GROUP BY If you want to return only specific groups from the query, you can apply filtering criteria at the group level by using the HAVING clause inside the GROUP BY clause. Note group functions can also... 2007-05-11, 6795👍, 0💬

Can Group Functions Be Mixed with Non-group Selection Fields
Can Group Functions Be Mixed with Non-group Selection Fields? - MySQL FAQs - SQL SELECT Query Statements with GROUP BY If a group function is used in the SELECT clause, all other selection fields must be group level fields. Non-group fields can not be mixed with group fields in the SELECT clause. Th... 2007-05-11, 5897👍, 0💬

How To Count Duplicated Values in a Column
How To Count Duplicated Values in a Column? - MySQL FAQs - SQL SELECT Query Statements with GROUP BY If you have a column with duplicated values, and you want to know what are those duplicated values are and how many duplicates are there for each of those values, you can use the GROUP BY ... HAVING ... 2007-05-11, 5669👍, 0💬

Can Multiple Columns Be Used in GROUP BY
Can Multiple Columns Be Used in GROUP BY? - MySQL FAQs - SQL SELECT Query Statements with GROUP BY If you want to break your output into smaller groups, if you specify multiple column names or expressions in the GROUP BY clause. Output in each group must satisfy a specific combination of the express... 2007-05-11, 5669👍, 0💬

How To Use SELECT Statement to Count the Number of Rows
How To Use SELECT Statement to Count the Number of Rows? - MySQL FAQs - SQL SELECT Query Statements with GROUP BY If you want to count the number of rows, you can use the COUNT(*) function in the SELECT clause. The following tutorial exercise shows you some good example: mysql> SELECT COUNT(*) FROM ... 2007-05-11, 5580👍, 0💬

Can Group Functions Be Used in the ORDER BY Clause
Can Group Functions Be Used in the ORDER BY Clause? - MySQL FAQs - SQL SELECT Query Statements with GROUP BY If the query output is aggregated as groups, you can sort the groups by using group functions in the ORDER BY clause. The following statement returns how many links were created in each year ... 2007-05-11, 5476👍, 0💬

How To Use Group Functions in the SELECT Clause
How To Use Group Functions in the SELECT Clause? - MySQL FAQs - SQL SELECT Query Statements with GROUP BY If group functions are used in the SELECT clause, they will be used on the rows that meet the query selection criteria, the output of group functions will be returned as output of the query. The... 2007-05-11, 5339👍, 0💬

What Are Group Functions
What Are Group Functions? - MySQL FAQs - SQL SELECT Query Statements with GROUP BY Group functions are functions applied to a group of rows. Examples of group functions are: COUNT(*) - Returns the number of rows in the group. MIN(exp) - Returns the minimum value of the expression evaluated on each r... 2007-05-11, 5292👍, 0💬

Can SELECT Statements Be Used on Views
Can SELECT Statements Be Used on Views? - MySQL FAQs - SQL SELECT Query Statements with GROUP BY Select (query) statements can be used on views in the same way as tables. The following tutorial exercise helps you creating a view and running a query statement on the view: mysql> CREATE VIEW myLinks A... 2007-05-11, 5223👍, 0💬

All rights in the contents of this web site are reserved by the individual author. fyicenter.com does not guarantee the truthfulness, accuracy, or reliability of any contents.