I am new to PDI/Kettle.I need to execute simple SQL select similar to "SELECT EMPID FROM Employee" and need to write the output to "Microsoft Excel Output" as part of reports generation.
When I write this query in "Execute SQL Statement" step under "SQL Scripts to execute" section in my transformation and execute it , it is returning nothing but transformation got completed without any errors.
No result written in my output file. The same behavior with the step "Execute Row SQL Script" by reading the input from sql file/data grid with query as input.
Transformation flow:
EXECUTE SQL STATEMENTS >> Microsoft Excel Output
EXECUTE SQL
STATEMENTS >> Textfile Output
If I use "Table Input" step and write the query under "SQL" section , it is getting executed and giving the result.
Table Input >> Microsoft Excel Output
Table Input >> Textfile Output
Can anyone help me in understanding this behavior and context/use cases of these steps.
Thank you techies for your knowledge share on this .
As per my understanding ,"Execute SQL statement" step is used to execute SQL statements like DDL, DML but it won't give any result to output stream except number of records impacted/affected(statistics) when we execute DML statements.
To track this statistics, there were optional fields give like insert stats, update stats, delete stats and read stats and based on your DML statement we can give the field name and number of records affected will be written as a value to that field. This can be noticed in "Preview data" under Transformation Execution results.
The Execute SQL Statement does not provide any result. Its purpose is DDL (Data Definition Language) to drop/create/truncate/alter tables, and DML (Data Manipulation Language) insert/update/delete rows.
Two checks (among other) should become a second nature after the coding of every step:
Check the output columns (right click on the step, choose Output fields).
Make a preview of the results (right click on the step, choose Preview).
Let me explain one basic concept of pentaho pdi (kettle): all the actions on kettle happens with a row. If there is no row, there will be no action. So if you add a generate row step at the begining of your transformation, with one dummy row with some value you will see how your sql statement will be triggered.
At a glance pentaho works with this 2 premises:
1 Everything is an asyncronous flow
2 Every action happens at row level. (no row, no action)
an input table step generates rows but an execute sql statement is not a input step type, is a transform step and expects rows generated already before this step.
I think this two basics concepts can help to understand how ketle works.
Related
I have a SQL Script with multiple drop & create DDL(Create tables As Select *), I want to run them at one go. I am quite new to informatica powercenter, can some one provide the process of using SQL transformation for BigQuery in informatica.
Sample Query:-
drop table if exists sellout.account_table;
CREATE TABLE sellout.account_table
AS
SELECT * FROM
sellout.account_src
WHERE
UPPER(account_name) IN ('RANDOM');
Similar to the above queries i have around 24 SQL's in a script.
I want to run them at once and later make them as part of informatica job.
If the "PowerExchange Google BigQuery" server and client are installed and after executing the infasetup.bat(sh) validateandregisterallfeatures, the mappings would be opened/exported successfully.
Here are some FAQs that might be handy for you:
Q: Why are the output fields in SQL Transformation not seen?
A: Stored Procedure selected in the SQL Transformation must have output parameters declared. Else it would not have output fields other than default Return Code column.
Q: A set of columns are displayed as result while running the Stored Procedure, however, you still do not see the same columns as output in SQL Transformation. Why?
A: Columns seen in the output might not be defined/declared as output parameters in the Stored Procedure. Procedure might have 'SELECT * FROM' like statement, which retrieves the data when the procedure is run from DB UI and a similar result could be seen when the procedure is run programmatically.
However, to call the same procedure from SQL Transformation, explicitly declared output parameters should be present as the transformation imports the metadata of the proc when selected. Unless you declare the output parameters explicitly in the procedure, it cannot be seen as output in the transformation.
Q: Is it necessary to have input/output parameters in Stored Procedure to call it from SQL Transformation?
A: Yes, it is necessary to have input/output parameters in Stored Procedure if it is not having default ones. As these parameters appear as input/output fields in SQL transformation, without these Mapping becomes invalid.
Q: I have SELECT statement in the procedure, does the SQL transformation can push this to next transforamtion?
A: Approprioate output parameters are required for this to work.
I have a table with a 'query' field containing a select sql and another 'parameters' field containing the sql parameters. I have already merged these two fields into a new field containing a correct select sql statement. Now I need to execute this new field containing select sql, get the return from select (the output fields) and generate an excel file.
In your transformation, you can use the Execute row SQL script (under scripting), which does exactly what you want, executing the SQL contained in the selected input field for each row passed to the step.
Please do consider if that's really what you want. It works fine for a small set or complicated logic, but is very inefficient compared to batch inserts and updates.
If your SQL statements do look like "INSERT [some data]" and you have many rows to process, consider splitting the streams with filter steps and applying calculations or constants to each case to set the values correctly, then directing all to a table output step.
I have created transformation which includes table input,sql step and excel o/p step.
Table input-->Run a query and get the field "query" which includes sql query select * from dual
Execute sql step-->Dynamically passing that query field using '?' and enabling variable substitution
Excel o/p-Expecting o/p is the sql query should be triggered and get the result in excel o/p
But i can't get the fiels from execute sql step.. How i can do this???
Thanks
Kavitha S
Use Database join instead of Execute SQL step. The Database Join step allows you to run a query against a database using data obtained from previous steps.
Database join Input: You can pass any of data you want from previous step using ? notation in SQL query defined inside the step.
Database join Output: Executes parametrized SQL query and adds new parameters as an output.
The step is what you need for your 2nd step. See more info about the Database join step in the documentation.
In PDI, "Execute SQL Step" is not meant for generating rows. It will not add any extra row to the data stream. You got Table Input step to generate multiple rows.
What you can try as an alternative is to break the transformation into two parts.
Part 1: Table Input Step > (query rows are generated) >> Use "Set variables" or "copy rows to result" to some other steps to set the query into some variable e.g: query.
Part 2: Take another Table Input Step (into a next .ktr file) and use the variable substitution of ${query} >> Finally output the result set to the excel output.
For dynamically sql queries, you can read this blog.
In case you have some lookups to do with the query generated, you can use Dynamic SQL row to generate the rows.
Hope it helps :)
I am using pentaho for data migration testing. I have set a "table input" step where many parts of the query inside "table inputs" are variables. I have been looking for a way to capture that query after it gets executed during runtime.
I was wondering if there is any specific system log variables for sql or is it to do with metadata. need help! Thanks
Maybe the following approach will help:
We assume a transformation reading a CSV file to get the dynamic portion of the SELECT statement (e.g. the columns) and setting the variable columns with it.
The second transformation uses this variable to generate the SELECT statement and store it into the variable sql_statement.
In the main transformation we use ${sql_statement} as the SELECT statement of the table input and write the data to an output file (that's the business process so to say). From the same input we copy the output to another path. There we add the current time as a field (use element "Get system data") and we add the generated SQL statement, join them as a cartesian product and group the result by the sql_statement. That way we can compute the first time and the last time that the statement was used. These results are written to a text file.
The last thing we need is a job calling the three transformations sequentially.
This is a sample output:
sql_statement;min_time;max_time
SELECT my_column FROM test_table;2014/05/08 00:41:21.143;2014/05/08 00:41:21.144
Thank you Marcus! I did some thing similar.
It works. awesome.
I gathered parts of queries from table field where they were kept and formed a full query in javascript. After that full query will be sent as parameter to a transformation that will run and log the query.
My project is in Visual Foxpro and I use MS SQL server 2008. When I fire sql queries in batch, some of the queries don't execute. However, no error is thrown. I haven't used BEGIN TRAN and ROLLBACK yet. What should be done ??
that all depends... You don't have any sample of your queries posted to give us an indication of possible failure. However, one thing I've had good response with from VFP to SQL is to build into a string (I prefer using TEXT/ENDTEXT for readabilty), then send that entire value to SQL. If there are any "parameter" based values that are from VFP locally, you can use "?" to indicate it will come from a variable to SQL. Then you can batch all in a single vs multiple individual queries...
vfpField = 28
vfpString = 'Smith'
text to lcSqlCmd noshow
select
YT.blah,
YT.blah2
into
#tempSqlResult
from
yourTable YT
where
YT.SomeKey = ?vfpField
select
ost.Xblah,
t.blah,
t.blah2
from
OtherSQLTable ost
join #tempSqlResult t
on ost.Xblah = t.blahKey;
drop table #tempSqlResult;
endtext
nHandle = sqlconnect( "your connection string" )
nAns = sqlexec( nHandle, lcSqlCmd, "LocalVFPCursorName" )
No I don't have error trapping in here, just to show principle and readability. I know the sample query could have easily been done via a join, but if you are working with some pre-aggregations and want to put them into temp work areas like Localized VFP cursors from a query to be used as your next step, this would work via #tempSqlResult as "#" indicates temporary table on SQL for whatever the current connection handle is.
If you want to return MULTIPLE RESULT SETs from a single SQL call, you can do that too, just add another query that doesn't have an "into #tmpSQLblah" context. Then, all instances of those result cursors will be brought back down to VFP based on the "LocalVFPCursorName" prefix. If you are returning 3 result sets, then VFP will have 3 cursors open called
LocalVFPCursorName
LocalVFPCursorName1
LocalVFPCursorName2
and will be based on the sequence of the queries in the SqlExec() call. But if you can provide more on what you ARE trying to do and their samples, we can offer more specific help too.