I am new to Cassandra and I am trying to run a simple query in CQL:
select aggregate_name as name, 'test' as test from aggregates;
and I get an error: Line 1: no viable alternative at input ''test''
The question is: how could I select string literal in Apache Cassandra?
I found an ugly workaround, if you really want to print a text value as a column:
cqlsh> select aggregate_name as name, blobAsText(textAsBlob('test')) as test from aggregates;
name | test
------+------
dude | test
CQL supports native Cassandra functions as a select_expression, so you can convert your string literal to a blob and back again as shown above. (source)
Related
I am trying to merge to a SQL Database using the following code in Databricks with pyspark
query = """
MERGE INTO deltadf t
USING df s
ON s.SLAId_Id = t.SLAId_Id
WHEN MATCHED THEN UPDATE SET *
WHEN NOT MATCHED THEN INSERT *
"""
driver_manager = spark._sc._gateway.jvm.java.sql.DriverManager
con = driver_manager.getConnection(url) #
stmt = con.createStatement()
stmt.executeUpdate(query)
stmt.close()
But I'm getting the following error:
SQLException: Malformed SQL Statement: Expected token 'USING' but found Identifier with value 't' instead at position 25.
Any thoughts on where might be going wrong?
I don't know why you're getting this exact error. However I believe there are a number of issues with what you are trying to do.
Running the query via JDBC makes it run in SQL Server only. Construct like WHEN MATCHED THEN UPDATE SET * / WHEN NOT MATCHED INSERT * will not work. Databricks accepts it, but for SQL Server you need to explicitly provide columns to update and values to insert (reference).
Also, do you actually have tables named deltadf and df in SQL Server? I suppose you have a Dataframe or temporary view named df... this will not work. As said, this query executes in SQL Server only. If you want to upload data from Dataframe use df.write.format("jdbc").save (reference).
See this Fiddle - if deltadf and df are tables, running this query in SQL Server (any version) will only complain about Incorrect syntax near '*'.
SQLException: Malformed SQL Statement: Expected token 'USING' but found Identifier with value 't' instead at position 25.
if you missed updating any specific field or specific syntax, you will get this error.
I performed merge operation its working fine for me without error, Please follow below reference .
Reference:
https://www.youtube.com/watch?v=i5oM2bUyH0o
https://docs.databricks.com/delta/delta-update.html#upsert-into-a-table-using-merge
https://www.sqlshack.com/sql-server-merge-statement-overview-and-examples/
I'm using node-postgres module and node 13.5. I'm trying to insert a unix timestamp to postgres timestmap column and it seems to work in dbeaver but when I run the code it doesn't work.
CREATE TABLE public.test (
column1 timestamp NULL
);
In dbeaver when I run my insert:
insert into test (column1 ) values ( $1 )
It opens up a dialog I type in my param as: to_timestamp(1) I hit ok and it inserts to my table without problem.
But when I use this code:
pool.query("INSERT INTO test (column1) VALUES ($1)", ["to_timestamp(1)"]);
I get an error:
error: invalid input syntax for type timestamp: "to_timestamp(1)"
the query method is the one from the module.
Also if I run like this:
pool.query("INSERT INTO test (column1) VALUES (to_timestamp(1))", []);
It works.
It seems like the nodejs driver doing something different from the dbeaver driver. Am I doing this wrong? Is there a way to to approach this problem? I'd like to use prepared statement if possible.
The things I can't change:
my data is in unix timestamp
the column must have timestamp type
Any help appreciated.
My college helped me:
pool.query("INSERT INTO test (column1) VALUES to_timestamp($1)", ["1"]);
This is the working solution!
I am writing a shell script which involves BigQuery commands to query an existing table and save the results to a destination table.
However, since my script will be run periodically, I have a parameter for the date for which the query should run.
For example, my script looks like this:
DATE_FORMATTED=$(date +%Y%m%d)
bq query --destination_table=Desttables.abc_$DATE_FORMATTED "select hits_eventInfo_eventLabel from TABLE_DATE_RANGE([mydata.table_],TIMESTAMP($DATE_FORMATTED),TIMESTAMP($DATE_FORMATTED)) where customDimensions_index = 4"
I get the following error:
Error in query string: Error processing job 'pro-cn:bqjob_r5437894379_1': FROM clause with table wildcards matches no table
How else can I pass the variable $DATE_FORMATTED to the TABLE_DATE_RANGE function from BigQuery in order to help execute my query?
Use double quotes "" + single quote ''. For example, in your case:
TIMESTAMP("'$DATE_FORMATTED'")
OR
select "'$variable'" as dummy from your_table
You are probably missing the single quotes around the $DATE_FORMATTED value inside the TIMESTAMP functions. Without the quotes it's going to be defaulting to the EPOCH time.
Try with:
TIMESTAMP('$DATE_FORMATTED'),TIMESTAMP('$DATE_FORMATTED')
$describe = new Cassandra\SimpleStatement(<<<EOD
describe keyspace.tablename
EOD
);
$session->execute($describe);
i used above code but it is not working.
how can i fetch field name and it's data type from Cassandra table ?
Refer to CQL documentation. Describe expects a table/schema/keyspace.
describe table keyspace.tablename
Its also a cqlsh command, not an actual cql command. To get this information query the system tables. try
select * from system.schema_columns;
- or for more recent versions -
select * from system_schema.columns ;
if using php driver may want to check out http://datastax.github.io/php-driver/features/#schema-metadata
Try desc table keyspace.tablename;
I write because I've a problem with cassandra; after have imported the data from pentaho as show here
http://wiki.pentaho.com/display/BAD/Write+Data+To+Cassandra
when I try to execute the query
Select * FROM mytable;
cassandre give me an error message
Syntax error at position 7: unexpected "*" for Select * FROM mytable;.
and don't show the results of query.Why? what does it mean that error?
the step that i make are the follow:
start cassandra cli utility;
use keyspace added from pentaho; (use tpc_h);
select to show the data added (Select * FROM mytable;)
The cassandra-cli does not support any CQL version. It has its own syntax which you can find on datastax's website.
Just for clarity, in cql to select everything from a table (aka column-family) called mytable stored in a keyspace called myks you would use:
SELECT * FROM myks.mytable;
The equivalent in cassandra-cli would *roughly be :
USE myks;
LIST mytable;
***** In the cli you are limited to selecting the first 100 rows. If this is a problem you can use the limit clause to specify how many rows you want:
LIST mytable limit 10000;
As for this:
in cassandra i have read that isn't possible make the join such as sql, ther isn't a shortcut to issue this disadvantage
There is a reason why joins don't exist in Cassandra, its for the same reason that C* isn't ACID compliant, it sacrifices that functionality for it's amazing performance and scalability, so it's not a disadvantage, you just need to re-think your model if you need joins. Also take a look at this question / answer.