Assign Names to Query Output Columns in MySQL

Q

How To Name Query Output Columns in MySQL?

✍: FYIcenter.com

A

Each column in the query output has a default name. If you don't like the default name, you can specify a new name for any column in the query output by using the AS clause. The following statement shows you a good example:

mysql> SELECT tag AS Category, YEAR(created) AS Year, 
   COUNT(*) AS Counts FROM fyi_links 
   GROUP BY tag, YEAR(created) ORDER BY COUNT(*) DESC;
+----------+------+--------+
| Category | Year | Counts |
+----------+------+--------+
| DBA      | 2006 |      2 |
| DEV      | 2006 |      1 |
| SQA      | 2006 |      1 |
| DBA      | 2005 |      1 |
| DEV      | 2004 |      1 |
| SQA      | 2003 |      1 |
+----------+------+--------+
6 rows in set (0.00 sec)

⇒ What Is a Subquery in MySQL

⇐ Inner Join with the WHERE Clause in MySQL

⇑ SELECT Statements with JOIN and Subqueries in MySQL

⇑⇑ MySQL Database Tutorials

2017-09-28, 2223🔥, 0💬

Using Table Alias Names in MySQL
How To Define and Use Table Alias Names in MySQL? When column names need to be prefixed with table names, you can define table alias name and use them to prefix column names as shown in the following select statement: mysql> SELECT l.id, l.url, r.comment FROM fyi_links l INNER JOIN fyi_rates ... 2017-12-31, 2482🔥, 0💬

Inner Join with the WHERE Clause in MySQL
How To Write an Inner Join with the WHERE Clause in MySQL? If you don't want to use the INNER JOIN ... ON clause to write an inner join, you can put the join condition in the WHERE clause as shown in the following query example: mysql> SELECT l.id, l.url, r.comment FROM fyi_links l, fyi_rates... 2017-09-28, 2437🔥, 0💬

Using Subqueries with the IN Operator in MySQL
How To Use Subqueries with the IN Operator in MySQL? A subquery can be used with the IN operator as "expression IN (subquery)". The subquery should return a single column with one or more rows to form a list of values to be used by the IN operation. The following tutorial exercise shows you how to u... 2017-09-17, 2434🔥, 0💬

Query with a Full Outer Join in MySQL
How To Write a Query with a Full Outer Join in MySQL? There is no way to do full outer join in MySQL. It does not support this feature at the current MySQL release. ⇒ Inner Join with the WHERE Clause in MySQL ⇐ Query with a Right Outer Join in MySQL ⇑ SELECT Statements with JOIN and Subqueries in... 2017-09-28, 2412🔥, 0💬

Using Subqueries with the EXISTS Operator in MySQL
How To Use Subqueries with the EXISTS Operator in MySQL? A subquery can be used with the EXISTS operator as "EXISTS (subquery)", which returns true if the subquery returns one or more rows. The following statement is a good example of "EXISTS (subquery)". It returns rows from fyi_links table that th... 2017-09-17, 2328🔥, 0💬

Query with a Left Outer Join in MySQL
How To Write a Query with a Left Outer Join in MySQL? If you want to query from two tables with a left outer join, you can use the LEFT OUTER JOIN ... ON clause in the FROM clause. The following query returns output with a left outer join from two tables: fyi_links and fyi_rates. The join condition ... 2017-09-28, 2319🔥, 0💬

Query with a Right Outer Join in MySQL
How To Write a Query with a Right Outer Join in MySQL? If you want to query from two tables with a right outer join, you can use the RIGHT OUTER JOIN ... ON clause in the FROM clause. The following query returns output with a right outer join from two tables: fyi_links and fyi_rates. The join condit... 2017-09-28, 2296🔥, 0💬

Using Subqueries in the FROM Clause in MySQL
How To Use Subqueries in the FROM clause in MySQL? If you have a query returning many rows of data, and you want to perform another query on those rows, you can put the first query as a subquery in the FROM clause of the second query. A subquery used in this way become a temporary table, and you mus... 2017-12-21, 2272🔥, 0💬

Counting Groups Returned from GROUP BY in MySQL
How To Count Groups Returned with the GROUP BY Clause in MySQL? If you use the COUNT(*) function on groups returned with the GROUP BY clause, it will count the number of rows within each group, not the number of groups. If you want to count the number of groups, you can put the GROUP BY query into a... 2017-12-21, 2254🔥, 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.