Is there any way to update an in-memory table dynamically using dolphindb? I need more suggestions to write a dynamic update function. Now I can only get the table name returned. I tried several methods to update the data for a specified table but failed.
Script 1:
table1=table(1..6 as id,2..7 as v, 3..8 as v1, 4..9 as v2, 5..10 as v3 );
share table1 as t1;
tableName ="t1";
update!(tableName, `v, 666);
Error report:
Read only object or object without ownership can't be applied to mutable function update!
Script 2:
updateSql = "update t1 set v = 999;";
parseExpr(updateSql).eval;
Error report:
Invalid expression: update t1 set v=999;
What's the correct syntax to update a specified table?
Use DolphinDB's function update! to update the columns in an existing table:
update!(table, colNames, newValues, [filter])
Here table is a DolphinDB table. The error occurs because your script defines the table type to be of STRING type. Use objByName to change it:
update!(objByName(tableName), `v, 666);
If you want to know more about dynamical expression generation, meta programming will be of help.
Related
I am trying to run an UPSERT query string on a postgres db -
insert into business_data_test
(select * from business_data_tmp)
on conflict(phone_number)
do update set
average_expense=(average_expense*expense_count + excluded.average_expense*excluded.expense_count)/(expense_count + excluded.expense_count), expense_count=(expense_count + excluded.expense_count);
I am basically trying to update the column average_expense if there is conflicting data, but I think there is something wrong with the query as I am running into the following error -
ERROR: column reference "average_expense" is ambiguous
LINE 1: ...lict(phone_number) do update set average_expense=(average_ex...
^
SQL state: 42702
Character: 123
I believe we have to add some table name alias somewhere but I am not sure how to fix this.
You need to full qualify the reference to the old values (i.e. the "non-exluded" ones). This is a bit easier if you use an alias for the target table
insert into business_data_test as tst
select *
from business_data_tmp
on conflict(phone_number)
do update
set average_expense = (tst.average_expense * tst.expense_count + excluded.average_expense * excluded.expense_count)/(tst.expense_count + excluded.expense_count),
expense_count = tst.expense_count + excluded.expense_count;
your query has "excluded." butno reference to what is that "excluded" is?
My suggestion, do the update with one single column value instead of the long computational logic. Make sure you get it working then add to that update logic....
Easier to debug that way.
Can somebody help me?
I am try execute the command below in Oracle 11 and I get this error:
SQL Error [905] [42000]: ORA-00905: keyword not found.
Code:
SELECT *
INTO SAJ.ETMP_TESTE
FROM SAJ.ESAJOBJETO O
WHERE CDOBJETO = 'P800000000J03'
I read the Oracle docs and haven't found any obvious error in my statement.
https://docs.oracle.com/cd/B19306_01/appdev.102/b14261/selectinto_statement.htm
My objective is to create the table ETMP_TESTE with structure from ESAJOBJETO.
I checked user permission and user has permission to action.
You need create table and not select into for create a table based on the result of a query
CREATE TABLE SAJ.ETMP_TESTE
AS SELECT *
FROM SAJ.ESAJOBJETO O
WHERE CDOBJETO = 'P800000000J03'
This will create an empty table named ETMP_TESTE, with the structure of the SAJ.EASJOBJETO table.
CREATE TABLE ETMP_TESTE AS
SELECT *
FROM SAJ.EASJOBJETO
WHERE 1 = 0;
This does not handle contraints and primary keys and things like that, but it will get you the table structure. The 1 = 0 makes sure no data is copied.
If you need primary keys and the like, look into extracting the DDL for EASJOBJETO. Most SQL IDEs have that functionality built in. You can edit it to correct the table name and run the script and get everything.
I need some help to resolve the problem that i wrote below,
UPDATE OYKUN_EMPLOYEE t1,table(t1.EMPMANAGER) t2 SET t2.value = 'ÖYKÜN' WHERE EMPNO=100
Its temporal database and I'm getting the error 'SET' keyword is missing. How can i handle this error.
EMPMANAGER is the column name which contains VT_LB, VT_UB, VALUE attributes. I'm using attribute timestamping approach
I am using APEX collections to store some values and pass them between pages in Oracle Application Express 4.2.3.
I would like to then perform an update statement on a table called "project" with the values from the collection.
My code so far is as follows:
update project
SET name=c.c002,
description=c.c007,
start_date=c.c004,
timeframe=c.c005,
status=c.c009
FROM
apex_collections c
WHERE
c.collection_name = 'PROJECT_DETAILS_COLLECTION'
and id = :p14_id;
where :p14_id is the value of a page item.
However, I am getting the following error:
ORA-00933: SQL command not properly ended
Anyone have any idea on how to approach this?
Thanks!
The UPDATE syntax you are using is not valid in Oracle; it does not allow you to use FROM in the way you are attempting.
The simplest way to do this in Oracle would with a subquery:
update project
set (name, description, start_date, timeframe, status) =
(select c.c002, c.c007, c.c004, c.c005, c.c009
FROM
apex_collections c
WHERE
c.collection_name = 'PROJECT_DETAILS_COLLECTION'
)
WHERE
id = :p14_id
;
Note that if the subquery returns no rows, the columns in the target table will be updated to NULL; this could be avoided by adding a similar EXISTS condition in the predicate for the update. It could also be avoided by using a MERGE statement instead of an UPDATE.
If the subquery returns multiple rows, the statement will throw an error. It looks like tthat should not be the case here.
How can I add a column in an SQLite table if and only if the same column does not exist in the table?
Using ALTER TABLE I am able to create a new column but want to know how to check whether that column already exists in the table or not?
SQLite returns an error like "no such column: foo" if the table doesn't contain the column:
select foo from yourTable limit 1
Also you can get the create-table statement:
select sql from sqlite_master where tbl_name = 'YourTableName'
and then parse the result, looking for the column-name. I don't know of an elegant way to query the list of columns for a specified table, though one may exist.
Also if you attempt to do this:
alter table YourTable add column foo {column-def whatever it is}
you get an error from SQLite if the column already exists. You could trap that error too.
Finally you could do this:
select sql from sqlite_master
where tbl_name = 'YOURTABLE' and sql like '%"foo" CHAR%'; -- or whatever type
and if the specified table contains the column which is surrounded by double-quotes in the query, and with the type you have specified, you will get a result, otherwise an empty set. Specifying the datatype ensures that your LIKE substring match occurs on a column-name.
There's no way (that I know of) to do it all in a single SQLite query. You must use application code to manage the If/Elseness.
Check if table exists or not:
select count(*) from sqlite_master where type = 'table' and name = MyTable';
Check if column exists in table or now
pragma table_info(thumbnail);
However, a better approach may be explicit database schema updates based on schema versions your application maintains (e.g. specific alter table statement to go from schema version 1 to 2):
pragma user_version;
It seems like that it is impossible to do checking if the column not exists and addindg the new column in one command, because Sqlite don't support "IF NOT EXISTS" for column. "IF NOT EXISTS" works only on table.
Here is what I will do:
rev = ExecuteStatement("SELECT columnNamexx FROM tableNamexx limit 1;");
if(rev != SQLITE_OK){ // add col to table
ExecuteStatement("ALTER TABLE tableNamexx ADD COLUMN columnNamexx INTEGER DEFAULT 0;");
}
You can view the table columns by using '.schema tableName'