Mysql aliased column unknown in the where clause

Question

I do not understand why mysql says that there is unknown column in where clause. If I remove alias and just use log_archive.date then it works just fine.

Here is the sql:

SELECT DISTINCT(log_archive.msisdn) AS msisdn,
       DATE(log_archive.date) AS actionDate,
       users.activation_date

        FROM log_archive 

        INNER JOIN users on log_archive.msisdn = users.msisdn

        WHERE log_archive.action = 'pokrenuta aplikacija' AND
              actionDate BETWEEN ':start_date' AND ':end_date'

        ORDER BY actionDate DESC

Here is the error message:

Unknown column 'actionDate' in 'where clause'

MySQL version is 5.1.36.

Answer 1

Column alias name can't be used in WHERE clause.

Reference:

http://dev.mysql.com/doc/refman/5.7/en/problems-with-alias.html

Standard SQL disallows references to column aliases in a WHERE clause. This restriction is imposed because when the WHERE clause is evaluated, the column value may not yet have been determined. For example, the following query is illegal:

Answer 2

Because your actionDate is not a aliased name of column, actionDate is a aliase of the result of function DATE

If change the sql as below, it's still working, so problem is not the aliased name, you must use the exactly column in where clause.

SELECT DISTINCT(log_archive.msisdn) AS msisdn,
       log_archive.date AS actionDate,
       users.activation_date
FROM log_archive 
INNER JOIN users on log_archive.msisdn = users.msisdn
WHERE log_archive.action = 'pokrenuta aplikacija' AND
     DATE(actionDate) BETWEEN ':start_date' AND ':end_date'
ORDER BY actionDate DESC

Answer 3

Column aliases can't be used in the WHERE clause. You can move that logic into a derived table:

SELECT DISTINCT msisdn, actionDate, activation_date
FROM
(
  SELECT log_archive.msisdn AS msisdn,
         DATE(log_archive.date) AS actionDate,
         users.activation_date AS activation_date
  FROM log_archive 
      INNER JOIN users on log_archive.msisdn = users.msisdn
  WHERE log_archive.action = 'pokrenuta aplikacija'
) dt
WHERE actionDate BETWEEN ':start_date' AND ':end_date'
ORDER BY actionDate DESC

Or, MySQL users only, have the column alias condition in a HAVING clause.

Or simply put DATE(log_archive.date) BETWEEN ... in the WHERE clause.

Answer 4

Column alias name can't be used in WHERE clause. Instead Having clause can be used.

SELECT DISTINCT
    (log_archive.msisdn) AS msisdn,
    DATE(log_archive.date) AS actionDate,
    users.activation_date
FROM
    log_archive
        INNER JOIN
    users ON log_archive.msisdn = users.msisdn
WHERE
    log_archive.action = 'pokrenuta aplikacija'
having actionDate BETWEEN ':start_date' AND ':end_date'
ORDER BY actionDate DESC

You can also do it by

SELECT DISTINCT
    (log_archive.msisdn) AS msisdn,
    DATE(log_archive.date) AS actionDate,
    users.activation_date
FROM
    log_archive
        INNER JOIN
    users ON log_archive.msisdn = users.msisdn
WHERE
    log_archive.action = 'pokrenuta aplikacija' AND DATE(log_archive.date) BETWEEN ':start_date' AND ':end_date'
ORDER BY actionDate DESC