I am having this table of words from multiple files. I want to count how many files each word shows. I can that with the piece of code below. But when I nest it with the CREATE TABLE statement, it won't work. The second piece of code below is the error code.
SELECT WORD, COUNT(*) FROM (select DISTINCT ABSTRACTID, WORD FROM NSFABSTRACTS)
GROUP BY WORD ORDER BY COUNT(*) DESC
CREATE TABLE DOC_FREQ (WORD, TOTALCOUNT) AS
(
SELECT WORD, COUNT(*) FROM (select DISTINCT ABSTRACTID, WORD FROM NSFABSTRACTS)
GROUP BY WORD ORDER BY COUNT(*));
Here is the error message:
SQL Error: ORA-00907: missing right parenthesis
00907. 00000 - "missing right parenthesis"
*Cause:
*Action:
Can anyone suggest how to create this table? Thanks.
You cannot use order by when you have the query enclosed in parentheses; at least if that clause is also within the parentheses:
create table t42 as (select * from dual order by dummy);
SQL Error: ORA-00907: missing right parenthesis
It is allowed outside:
create table t42 as (select * from dual) order by dummy;
table T42 created.
You can remove the parentheses as they aren't needed at all here:
create table t42 as select * from dual order by dummy;
table T42 created.
Or remove the order by, since an order by in the create statement usually makes little difference and doesn't affect how the data is retrieved:
create table t42 as (select * from dual);
table T42 created.
Or preferably for my tastes, both:
create table t42 as select * from dual;
table T42 created.
Related
ّ am trying to insert multiple records got from the join table to another table user_to_property. In the user_to_property table user_to_property_id is primary, not null it is not autoincrementing. So I am trying to add user_to_property_id manually by an increment of 1.
WITH selectedData AS
( -- selection of the data that needs to be inserted
SELECT t2.user_id as userId
FROM property_lines t1
INNER JOIN user t2 ON t1.account_id = t2.account_id
)
INSERT INTO user_to_property (user_to_property_id, user_id, property_id, created_date)
VALUES ((SELECT MAX( user_to_property_id )+1 FROM user_to_property),(SELECT
selectedData.userId
FROM selectedData),3,now());
The above query gives me the below error:
ERROR: more than one row returned by a subquery used as an expression
How to insert multiple records to a table from the join of other tables? where the user_to_property table contains a unique record for the same user-id and property_id there should be only 1 record.
Typically for Insert you use either values or select. The structure values( select...) often (generally?) just causes more trouble than it worth, and it is never necessary. You can always select a constant or an expression. In this case convert to just select. For generating your ID get the max value from your table and then just add the row_number that you are inserting: (see demo)
insert into user_to_property(user_to_property_id
, user_id
, property_id
, created
)
with start_with(current_max_id) as
( select max(user_to_property_id) from user_to_property )
select current_max_id + id_incr, user_id, 3, now()
from (
select t2.user_id, row_number() over() id_incr
from property_lines t1
join users t2 on t1.account_id = t2.account_id
) js
join start_with on true;
A couple notes:
DO NOT use user for table name, or any other object name. It is a
documented reserved word by both Postgres and SQL standard (and has
been since Postgres v7.1 and the SQL 92 Standard at lest).
You really should create another column or change the column type
user_to_property_id to auto-generated. Using Max()+1, or
anything based on that idea, is a virtual guarantee you will generate
duplicate keys. Much to the amusement of users and developers alike.
What happens in an MVCC when 2 users run the query concurrently.
This question already has answers here:
sql server 2008 management studio not checking the syntax of my query
(2 answers)
Closed 1 year ago.
I have the following select:
SELECT DISTINCT pl
FROM [dbo].[VendorPriceList] h
WHERE PartNumber IN (SELECT DISTINCT PartNumber
FROM [dbo].InvoiceData
WHERE amount > 10
AND invoiceDate > DATEADD(yyyy, -1, CURRENT_TIMESTAMP)
UNION
SELECT DISTINCT PartNumber
FROM [dbo].VendorDeals)
The issue here is that the table [dbo].VendorDeals has NO column PartNumber, however no error is detected and the query works with the first part of the union.
Even more, IntelliSense also allows and recognize PartNumber. This fails only when inside a complex statement.
It is pretty obvious that if you qualify column names, the mistake will be evident.
This isn't a bug in SQL Server/the T-SQL dialect parsing, no, this is working exactly as intended. The problem, or bug, is in your T-SQL; specifically because you haven't qualified your columns. As I don't have the definition of your table, I'm going to provide sample DDL first:
CREATE TABLE dbo.Table1 (MyColumn varchar(10), OtherColumn int);
CREATE TABLE dbo.Table2 (YourColumn varchar(10) OtherColumn int);
And then an example that is similar to your query:
SELECT MyColumn
FROM dbo.Table1
WHERE MyColumn IN (SELECT MyColumn FROM dbo.Table2);
This, firstly, will parse; it is a valid query. Secondly, provided that dbo.Table2 contains at least one row, then every row from table dbo.Table1 will be returned where MyColumn has a non-NULL value. Why? Well, let's qualify the column with table's name as SQL Server would parse them:
SELECT Table1.MyColumn
FROM dbo.Table1
WHERE Table1.MyColumn IN (SELECT Table1.MyColumn FROM dbo.Table2);
Notice that the column inside the IN is also referencing Table1, not Table2. By default if a column has it's alias omitted in a subquery it will be assumed to be referencing the table(s) defined in that subquery. If, however, none of the tables in the sub query have a column by that name, then it will be assumed to reference a table where that column does exist; in this case Table1.
Let's, instead, take a different example, using the other column in the tables:
SELECT OtherColumn
FROM dbo.Table1
WHERE OtherColumn IN (SELECT OtherColumn FROM dbo.Table2);
This would be parsed as the following:
SELECT Table1.OtherColumn
FROM dbo.Table1
WHERE Table1.OtherColumn IN (SELECT Table2.OtherColumn FROM dbo.Table2);
This is because OtherColumn exists in both tables. As, in the subquery, OtherColumn isn't qualified it is assumed the column wanted is the one in the table defined in the same scope, Table2.
So what is the solution? Alias and qualify your columns:
SELECT T1.MyColumn
FROM dbo.Table1 T1
WHERE T1.MyColumn IN (SELECT T2.MyColumn FROM dbo.Table2 T2);
This will, unsurprisingly, error as Table2 has no column MyColumn.
Personally, I suggest that unless you have only one table being referenced in a query, you alias and qualify all your columns. This not only ensures that the wrong column can't be referenced (such as in a subquery) but also means that other readers know exactly what columns are being referenced. It also stops failures in the future. I have honestly lost count how many times over years I have had a process fall over due to the "ambiguous column" error, due to a table's definition being changed and a query referencing the table wasn't properly qualified by the developer...
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What are differences between SQL queries?
(1 answer)
Closed 4 years ago.
This syntax is valid for PostgreSQL:
select T from table_name as T
T seems to become a CSV list of values from all columns in table_name. select T from table_name as T works, and, for that matter, select table_name from table_name. Where is this syntax documented, and what is the datatype of T?
This syntax is not in SQL Server, and (AFAIK) does not exist in any other SQL variant.
If you create a table, Postgres creates a type with the same name in the background. The table is then essentially a "list of that type".
Postgres also allows to reference a complete row as a single "record" - a value built from multiple columns. Those records can be created dynamically through a row constructor.
Each row in a the result of a SELECT statement is implicitly assigned a TYPE - if the row comes from a single table, it's the table's type. Otherwise it's an anonymous type.
When you use the table name in a place where a column would be allowed it references the full row as a single record. If the table is aliased in the select, the type of that record is still the table's type.
So the statement:
select T
from table_name as T;
returns a result with a single column which is a record (of the table's type) containing each column of the table as a field. The default output format of a record is a comma separated list of the values enclosed in parentheses.
Assuming table_name has three columns c1, c2 and c3 the following would essentially do the same thing:
select row(c1, c2, c3)
from table_name;
Note that a record reference can also be used in comparisons, e.g. finding rows that are different between two tables can be done in the following manner
select *
from table_one t1
full outer join table_two t2 on t1.id = t2.id
where t1 <> t2;
Is it possible to SELECT * but without n-th column, for example 2nd?
I have some view that have 4 and 5 columns (each has different column names, except for the 2nd column), but I do not want to show the second column.
SELECT * -- how to prevent 2nd column to be selected?
FROM view4
WHERE col2 = 'foo';
SELECT * -- how to prevent 2nd column to be selected?
FROM view5
WHERE col2 = 'foo';
without having to list all the columns (since they all have different column name).
The real answer is that you just can not practically (See LINK). This has been a requested feature for decades and the developers refuse to implement it. The best practice is to mention the column names instead of *. Using * in itself a source of performance penalties though.
However, in case you really need to use it, you might need to select the columns directly from the schema -> check LINK. Or as the below example using two PostgreSQL built-in functions: ARRAY and ARRAY_TO_STRING. The first one transforms a query result into an array, and the second one concatenates array components into a string. List components separator can be specified with the second parameter of the ARRAY_TO_STRING function;
SELECT 'SELECT ' ||
ARRAY_TO_STRING(ARRAY(SELECT COLUMN_NAME::VARCHAR(50)
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME='view4' AND
COLUMN_NAME NOT IN ('col2')
ORDER BY ORDINAL_POSITION
), ', ') || ' FROM view4';
where strings are concatenated with the standard operator ||. The COLUMN_NAME data type is information_schema.sql_identifier. This data type requires explicit conversion to CHAR/VARCHAR data type.
But that is not recommended as well, What if you add more columns in the long run but they are not necessarily required for that query?
You would start pulling more column than you need.
What if the select is part of an insert as in
Insert into tableA (col1, col2, col3.. coln) Select everything but 2 columns FROM tableB
The column match will be wrong and your insert will fail.
It's possible but I still recommend writing every needed column for every select written even if nearly every column is required.
Conclusion:
Since you are already using a VIEW, the simplest and most reliable way is to alter you view and mention the column names, excluding your 2nd column..
-- my table with 2 rows and 4 columns
DROP TABLE IF EXISTS t_target_table;
CREATE TEMP TABLE t_target_table as
SELECT 1 as id, 1 as v1 ,2 as v2,3 as v3,4 as v4
UNION ALL
SELECT 2 as id, 5 as v1 ,-6 as v2,7 as v3,8 as v4
;
-- my computation and stuff that i have to messure, any logic could be done here !
DROP TABLE IF EXISTS t_processing;
CREATE TEMP TABLE t_processing as
SELECT *, md5(t_target_table::text) as row_hash, case when v2 < 0 THEN true else false end as has_negative_value_in_v2
FROM t_target_table
;
-- now we want to insert that stuff into the t_target_table
-- this is standard
-- INSERT INTO t_target_table (id, v1, v2, v3, v4) SELECT id, v1, v2, v3, v4 FROM t_processing;
-- this is andvanced ;-)
INSERT INTO t_target_table
-- the following row select only the columns that are pressent in the target table, and ignore the others.
SELECT r.* FROM (SELECT to_jsonb(t_processing) as d FROM t_processing) t JOIN LATERAL jsonb_populate_record(NULL::t_target_table, d) as r ON TRUE
;
-- WARNING : you need a object that represent the target structure, an exclusion of a single column is not possible
For columns col1, col2, col3 and col4 you will need to request
SELECT col1, col3, col4 FROM...
to omit the second column. Requesting
SELECT *
will get you all the columns
I don't understand why the following doesn't fail. How does the subquery have access to a column from a different table at the higher level?
drop table if exists temp_a;
create temp table temp_a as
(
select 1 as col_a
);
drop table if exists temp_b;
create temp table temp_b as
(
select 2 as col_b
);
select col_a from temp_a where col_a in (select col_a from temp_b);
/*why doesn't this fail?*/
The following fail, as I would expect them to.
select col_a from temp_b;
/*ERROR: column "col_a" does not exist*/
select * from temp_a cross join (select col_a from temp_b) as sq;
/*ERROR: column "col_a" does not exist
*HINT: There is a column named "col_a" in table "temp_a", but it cannot be referenced from this part of the query.*/
I know about the LATERAL keyword (link, link) but I'm not using LATERAL here. Also, this query succeeds even in pre-9.3 versions of Postgres (when the LATERAL keyword was introduced.)
Here's a sqlfiddle: http://sqlfiddle.com/#!10/09f62/5/0
Thank you for any insights.
Although this feature might be confusing, without it, several types of queries would be more difficult, slower, or impossible to write in sql. This feature is called a "correlated subquery" and the correlation can serve a similar function as a join.
For example: Consider this statement
select first_name, last_name from users u
where exists (select * from orders o where o.user_id=u.user_id)
Now this query will get the names of all the users who have ever placed an order. Now, I know, you can get that info using a join to the orders table, but you'd also have to use a "distinct", which would internally require a sort and would likely perform a tad worse than this query. You could also produce a similar query with a group by.
Here's a better example that's pretty practical, and not just for performance reasons. Suppose you want to delete all users who have no orders and no tickets.
delete from users u where
not exists (select * from orders o where o.user_d = u.user_id)
and not exists (select * from tickets t where t.user_id=u.ticket_id)
One very important thing to note is that you should fully qualify or alias your table names when doing this or you might wind up with a typo that completely messes up the query and silently "just works" while returning bad data.
The following is an example of what NOT to do.
select * from users
where exists (select * from product where last_updated_by=user_id)
This looks just fine until you look at the tables and realize that the table "product" has no "last_updated_by" field and the user table does, which returns the wrong data. Add the alias and the query will fail because no "last_updated_by" column exists in product.
I hope this has given you some examples that show you how to use this feature. I use them all the time in update and delete statements (as well as in selects-- but I find an absolute need for them in updates and deletes often)