Query:
Column without function:
SELECT ACCOUNTID from table order by ACCOUNTID;
(Above query works fine in both HIVE & MYSQL)
Column with function:
SELECT concat('test_',ACCOUNTID) from table order by ACCOUNTID;
In mysql , Above query working fine.
In hive, below exception thrown
FAILED: SemanticException [Error 10004]:
Line 1:59 Invalid table alias or column reference 'ACCOUNTID':
(possible column names are: _c0)
Mysql :
Order by working fine with columns involved in functions
Hive :
Order by is not working with columns involved in functions
Temporary Solution :
SELECT concat('test_',ACCOUNTID) as tempColumn from table order by tempcolumn;
Is there any solution available without assigning column as tempcolumn ?
Note:
i want concatenated result alone(test_ACCOUNTID).. without exposing ACCOUNTID as another column
Maybe you can also select the accountid column for sorting.
SELECT accountid,concat('test_',ACCOUNTID) from table order by accountid;
Or, rename "concat('test_', accountid) " as accountid, like this:
SELECT concat('test_',ACCOUNTID) accountid from table order by accountid;
Depends on what you're trying to achieve. If you want your concatenated results to appear in the order of account id then you can expose ACCOUNTID in the projection list
SELECT concat('test_',ACCOUNTID), ACCOUNTID FROM <table> ORDER BY ACCOUNTID
As per my knowledge,its the only way to use alias-name for function expression and use clauses like 'Group By','Order By','Sort By' using that alias-name.
Related
I want to run two mysql SELECT statements, combine them, call the new combination by its own name, then order that new combination by a user-defined function. This is what I am trying currently:
SELECT * FROM (
SELECT * FROM dictionary WHERE def1 LIKE '$input%'
UNION ALL
SELECT * FROM dictionary WHERE def2 LIKE '$input%'
) AS newcol
ORDER BY levenshtein('$input', newcol)
LIMIT 10
But I get the following error:
Unable to run query:Unknown column 'newcol' in 'order clause'
The problem is clearly with defining the new group 'newcol'.
You're trying to order by a TABLE, not by a FIELD! Use a field from your tables ant it'll go smooth
Is there any way to do something like :
SELECT * FROM TABLE WHERE COLUMN_NUMBER = 1;
?
No, you can't. Column order doesn't really matter in MySQL. See the below question for more details.
mysql - selecting values from a table given column number
If your table has a column named COLUMN_NUMBER and you want to retrieve rows from the table where that column contains a value of '1', that query should do the trick.
I suspect that what you are trying to do is reference an expression in the select list with an alias. And that is not supported. An expression in the WHERE clause that references a column must reference the column by name.
We can play some tricks with inline views, to give an alias to an expression, but this is not efficient in terms of WHERE predicates, because of the way MySQL materializes a derived table. And, in that case, its a name given to the column in the inline view that has to be referenced in the outer query.
How I did it:
I'm trying to take (last 3 values of) column number 4 in sometable.
set #mydb=(SELECT DATABASE());
set #mycol=(select COLUMN_NAME from information_schema.columns where
table_schema=#mydb and table_name='sometable' and ordinal_position = 4);
SELECT Date,#mycol FROM sometable ORDER BY Date DESC LIMIT 3;
Of course, if Database name is known, first line could by whiped and #mydb replaced by real database name.
You can do this trick
Example:
$query="select * from employee";
$result=mysql_query($query);
$meta=mysql_fetch_field($result,0) // 0 is first field in table , 1 is second one ,,, etc
$theNameofFirstField=$meta->name; // this well return first field name in table
// now you can use it in other query
$seconQuery="select $theNameofFirstField from employee";
Can we use aliased field name in ORDER BY clause?
For example:
SELECT id, name AS firstname
FROM users
ORDER BY firstname
Is it possible? When I tried this it errored out.
An alias can be used in a query select list to give a column a
different name. You can use the alias in GROUP BY, ORDER BY, or HAVING
clauses to refer to the column.
Check here.
Try with this one, I have added back-ticks to column name and table Because name is the reserved word :
SELECT `id`, `name` AS firstname
FROM `users`
ORDER BY firstname
Yes, you can certainly use column aliases in your "order by" clause.
You can verify it works with the built-in mySql "user" table:
select User as name,Host from user order by name;
If it "errored out", then something else must have been wrong with your query. Please cut/paste the exact error message.
You cannot use alias in GROUP BY Clause in MS SQL SERVER
In order to tell of you can use aliases in certain clauses, check the order in which SQL procceses the the queries and it is as follows:
-from
-where
-group by
-having
-order by
I am creating a utility which lets users enter a SQL query for the purposes of importing data to my database.
The first step is to show a list of resulting fields so the user can route them to the destination fields.
When users import from MSSQL, I can use SET FMTONLY ON to fetch the list of output columns that the query would produce if ran (assuming the query is valid in the first place).
I haven't been able to find a way to do this for MySQL. EXPLAIN doesn't list the resulting fields.
Given the following query:
SELECT CONCATENATE(first_name, " ", last_name) AS name, age, foo
FROM customers
ORDER BY name ASC;
I ultimately need to get a list of output fields only, like this:
{ "name", "age", "foo" }
How can I do this in MySQL?
SET FMTONLY ON still requires you to get the column names and types manually, it just generates an empty result set.
For MySQL, add a WHERE FALSE somewhere
SELECT CONCATENATE(first_name, " ", last_name) AS name, age, foo
FROM customers
WHERE FALSE
ORDER BY name ASC;
You get this lovely execution plan
"id";"select_type";"table";"type";"possible_keys";"key";"key_len";"ref";"rows";"Extra"
"1";"SIMPLE";NULL;NULL;NULL;NULL;NULL;NULL;NULL;"Impossible WHERE"
Then parse the columns as you would set fmtonly on with MSSQL
For complex queries (nested, group by, limit-ed), wrap it in a subquery
select * from (
<your wonderful brilliant complex query>
) x where false
MSSQL would have complained if the inner query contains ORDER BY without TOP, MySQL is ok with it.
I think you need to look at the resultsetmetada. I carries the number of columns, column name, and a few more about the result set.
I think you're looking for DESC {table_name}
I'm storing a list of numbers inside a table as a varchar(255) and want to use this list in another query's "IN() clause.
Here's what I mean:
Table Data:
CREATE TABLE IF NOT EXISTS `session_data` (
`visible_portf_ids` varchar(255) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
INSERT INTO `session_data` (`visible_portf_ids`) VALUES
('45,44,658,659,661,45,44,658,659,661')
I want to run a query like this to return a list of portfolio's "QUERY #1":
SELECT portfolio_hierarchy_id, account_id, name, leaf_node_portf_id
FROM portfolio_hierarchy
WHERE account_id = 1
AND leaf_node_portf_id IN
(
(SELECT visible_portf_ids
FROM session_data
WHERE username = 'ronedog')
)
ORDER BY name ASC
The result of the query above returns only 1 row, when there are a total of 3 that should have been returned.
If I run the subquery alone like this:
(SELECT visible_portf_ids
FROM session_data
WHERE username = 'ronedog')
it will return a list like this:
45,44,658,659,661,45,44,658,659,661
But, when I run Query #1 above, only one row of data, which is associated with the "visible_portf_ids" of "45" is returned.
If I replace the subquery with hard coded values like this:
SELECT portfolio_hierarchy_id, account_id, name, leaf_node_portf_id
FROM portfolio_hierarchy
WHERE account_id = 1
AND leaf_node_portf_id IN (45,44,658,659,661,45,44,658,659,661)
ORDER BY name ASC
then I get all 3 rows I'm expecting.
I'm guessing that MySql is returning the list as a string because its stored as a varchar() and so it stops processing after the first "visible_portf_ids" is found, which is "45", but I'm not really sure.
Anyone got any ideas how I can fix this?
Thanks in advance.
You should think about restructuring your tables storing each value in a new row, instead of concatenating them.
Until then, you can use the FIND_IN_SET() function:
AND FIND_IN_SET(leaf_node_portf_id,
(SELECT visible_portf_ids
FROM session_data
WHERE username = 'ronedog'
LIMIT 1)
) > 0
Unfortunately MySQL does not have a function to split a delimited string. Your IN argument is a single string with the result of your subquery. The reason it works when you hard-code it is that MySQL is parsing the values.
I suggest that you redesign your data base to store the visible ports list as separate rows in a separate table. Then you can retrieve them and use them in subqueries like you tried.