DB Procedure to Dynamically update DB columns - sql

Question

Requirement is to update in db column only those column which are edited from frontend.
Logic i am using is to send 2 arrays from java code to DB procedire.
1st array is: Column_array which contains column names which have to be updated.
&
2nd array : value_array which contains the values of columns respoctive to the column_array.
From JAVA:
Array value_array = ((OracleConnection) dbConnection).createOracleArray("STRING_ARRAY",
valueList.toArray());
Array param_array = ((OracleConnection) dbConnection).createOracleArray("STRING_ARRAY",
paramList.toArray());
stmt = dbConnection.prepareCall(SqlConstants.UPDATE_SUBSCRIBER_CONFIG_IN_BOLTES);//
stmt.setLong(1, 3628);
stmt.setLong(2, 3629);
stmt.setLong(3, 3632);
stmt.setArray(4, param_array);
stmt.setArray(5, value_array);
int count = stmt.executeUpdate();
NOW at DB side:
how can i iterate over this list to update and set this in SET clause???
PROCEDURE update_subscriber_config (
p_app_id VARCHAR2,
p_service_id VARCHAR2,
p_pubsub_id VARCHAR2,
column_list string_array,
value_list string_array
)
AS
BEGIN
FOR a IN 1..column_list.count LOOP
update bolt_oracle_pubsub_config set
column_list(a)=value_list(a),
...how to do iteration here???
where APP_ID = p_app_id AND SERVICE_ID = p_service_id AND PUBSUB_ID = p_pubsub_id;
END LOOP;
END update_subscriber_config;
PLEASE HELP.

Answer 1

I found the solution which was simpler than array iteration.
Solution is to use COALESCE method.
PROCEDURE TEST (
p_app_id NUMBER,
p_service_id NUMBER,
p_pubsub_id NUMBER,
p_pubsub_name VARCHAR2,
p_host VARCHAR2,
p_user_name VARCHAR2,
p_auth_key VARCHAR2
)
AS
BEGIN
update bolt_elastic_pubsub_config set
PUBSUB_NAME = coalesce(p_pubsub_name, PUBSUB_NAME),
HOST = coalesce(p_host, HOST),
USER_NAME = coalesce(p_user_name, USER_NAME),
AUTH_KEY = coalesce(p_auth_key, AUTH_KEY)
where APP_ID = p_app_id AND SERVICE_ID = p_service_id AND PUBSUB_ID = p_pubsub_id;
END TEST;

Answer 2

You have to use dynamic SQL to assemble bespoke update statements. It will look something like this:
PROCEDURE update_subscriber_config (
p_app_id VARCHAR2,
p_service_id VARCHAR2,
p_pubsub_id VARCHAR2,
column_list string_array,
value_list string_array
)
AS
stmt varchar2(32767);
BEGIN
stmt := 'update bolt_oracle_pubsub_config set ';
FOR a IN 1..column_list.count LOOP
if a != 1 then
stmt := stmt ||', ';
end if;
stmt := stmt || column_list(a) ||'=''' ||value_list(a)||'''';
END LOOP;
stmt := stmt ||
' where APP_ID = :p1 AND SERVICE_ID = :p2 AND PUBSUB_ID = :p3';
execute immediate stmt using p_app_id , p_service_id , p_pubsub_id;
END update_subscriber_config;
This is a very crude implemnentation, as it assumes all the passed columns can be treated as strings. If your table has numeric or date columns you should think about handling data conversion, because that could become a problem.
Dynamic SQL is hard because it turns compilation errors into runtime errors. In your case you have a piece of code which potentially executes a different update statement every time you call it. So testing this procedure is a total nightmare. This means you have a heavy dependency on the front end passing arrays with valid contents.

Answer 3

Perhaps you could try avoiding one of the arrays which are the column array as Oracle SQL would tolerate if the value is null.
The below is the pseudo code.
PROCEDURE update_subscriber_config (p_app_id VARCHAR2,
p_service_id VARCHAR2,
p_pubsub_id VARCHAR2,
p_first_column VARCHAR2,
p_second_column VARCHAR2,
--column_list string_array,
i_array IN my_array_type)
AS
BEGIN
FORALL i IN 1 .. i_array.COUNT
UPDATE bolt_oracle_pubsub_config
SET your_first_column =
TREAT (i_array (i) AS my_array_type).column_array_name,
your_second_column =
TREAT (i_array (i) AS my_array_type).second_column_array_name
WHERE APP_ID = p_app_id
AND SERVICE_ID = p_service_id
AND PUBSUB_ID = p_pubsub_id;
END update_subscriber_config;
If any of the columns which are stated in the update SQL is empty, it would be null or empty in the table after executing the update. Having said that, ensure all NOT NULL or mandatory columns are populated.
I would reckon to avoid the dynamic SQL update due to error-prone. If you achieve the results without using dynamic SQL, then why the hassle with dynamic SQL update.