I have source server and destination server, i have insert the data from source to destination, but before that i have to delete the records if any in destination - (DTS)
If you want to remove whole existing table than create sql task and write :
drop table (tablename)
If you want to remove only data inside existing table than create sql task and write :
truncate table (tablename)
Create an Execute SQL task in the correct sequence of your package and call the following code to delete the rows
TRUNCATE TABLE tablename
Refer MSDN link for more details
Related
Here is my situation. Iam using Alteryx ETL tool where in basically we are appending new records to tableau by using option provided like 'Overwrite the file'.
What it does is any data incoming is captured to the target and delete the old data--> publish results in Tableau visualisation tool.
So whatever data coming in source must overwrite the existing data in Sink table.
How can we achieve this in Azure data Flow?
If you are writing to a database table, you'll see a sink setting for "truncate table" which will remove all previous rows and replace them with your new rows. Or if you are trying to overwrite just specific rows based on a key, then use an Alter Row transformation and use the "Update" option.
If your requirement is just to copy data from your source to target and truncate the table data before the latest data is copied, then you can just use a copy activity in Azure Data factory. In copy activity you have an option called Pre-copy script, in which you can specify a query to truncate the table data and then proceed with copying the latest data.
Here is an article by a community volunteer where a similar requirement has been discussed with various approaches - How to truncate table in Azure Data Factory
In case if your requirement is to do data transformation first and then copy the data to your target sql table and truncate table before your copy the latest transformed data then, you will have to use mapping data flow activity.
The source of my Copy activity is the result of calling a REST API and the Sink is a Azure SQL Table that I insert those records in it.
Now I want to know what records we just got inserted in that Sink so I can do some update statement on those records. So my question is how can I know what went into Sink so I can now update those records.
Two methods come to mind
If the table has a timestamp of when the records were inserted then you could use that value to know which were just inserted.
Instead of putting the records directly in the final table put them in a staging table. Then you can either update as part of the insert to move them to the final table do the updates OR update them in staging table and then copy over to the final table. Just remember to truncate the staging table every run so it only has the new records.
I want to run a presql script in the Data flow in SINK. I want to delete exiting records for particular year.
This particular year will be coming from source excel file.
Say I have a file for 2021 data and loaded that data into DB. when I rerun the pipeline for the same excel file I want to delete 2021 related records in DB and insert fresh. This table may contain multiple years data. So everytime a new file arrives for a particular year, I want to delete that respective records and reload the new data.
I can read the year value from source file column. And I can keep it as derived column. How Can I write a presql script to delete?
delete from where year = <sourcefile.year>
how can i do this in data flow?
Pls help!
You can use a temporary table in sink1 and delete the records in the sink2.
Please follow the demonstration below:
This is my SQL table with a sample data.
Create two SQL sinks for it from same source using a new branch.
In the first sink, provide a dataset with edit table name option for the temporary table.
In sink check on Recreate table.
In sink 2, give your SQL table with the below SQL script.
DELETE FROM exceltable WHERE year in (select year from dbo.temp1)
drop table dbo.temp1;
In the settings of Data flow give the Write order of sinks.
Temporary table sink should execute first.
This is my result in the SQL table after deleting records.
I am new to ADF. I have a pipeline which deletes all rows of any of the attributes are null. Schema : { Name, Value, Key}
I tried using a data flow with Alter Table and set both source and sink to be the same table but it always appends to the table instead of overwriting it which creates duplicate rows and the rows I want to delete still remain. Is there a way to overwrite the table.
Assuming that your table is SQL table, I have tried to overwrite the source table after deleting the specific null values. It successfully deleted the records but got the duplicate records even after exploring various methods.
So, as an alternate you can try the below methods to achieve your requirement:
By Creating new table and deleting old table:
This is my sample source table names mytable.
Alter transformation
Give new table in the sink and in settings->post SQL scripts. give the drop command to delete the source dataset. Now your sink table is your required table. drop table [dbo].[mytable]
Result table(named newtable) and old table.
Source table deleted.
Deleting null values from source table using script activity
Use script activity to delete the null values from source table.
Source table after execution.
I have deployed 9 node cluster on google cloud.
Created a table and loaded the data. Now want to change the table name.
Is there any way I can change the table name in Cassandra?
Thanks
You can't rename table name.
You have to drop the table and create again
You can use ALTER TABLE to manipulate the table metadata. Do this to change the datatype of a columns, add new columns, drop existing columns, and change table properties. The command returns no results.
Start the command with the keywords ALTER TABLE, followed by the table name, followed by the instruction: ALTER. ADD, DROP, RENAME, or WITH. See the following sections for the information each instruction require
If you need the data you can backup and restore data using copy command in cqlsh.
To Backup data :
COPY old_table_name TO 'data.csv'
To Restore data :
COPY new_table_name FROM 'data.csv'