How to restrict any DML operation in a stored procedure - sql

Question

I am trying to insert some records into a table for a particular month. How do I restrict any DML operations on that table for rest of the other months in a stored procedure (without any trigger or constraints). Please help me on this, Thanks in advance.

Answer 1

Pass the "particular month" as a parameter and use it in code throughout the procedure, most probably in WHERE clauses or IFs, CASEs etc.

Answer 2

Create 2 users:
The first (we can call it DATA_OWNER) will own the tables containing the data and the stored procedures/packages that perform the DML on those tables; and
The second (we can call it END_USER) will be the database user that your end users connect as.
Then you can create the tables:
CREATE TABLE data_owner.table_name (
id NUMBER
GENERATED ALWAYS AS IDENTITY
PRIMARY KEY,
datetime DATE
NOT NULL,
value NUMBER
);
CREATE TABLE data_owner.table_name_insert_bounds (
start_datetime DATE,
end_datetime DATE,
CONSTRAINT table_name_insert_bounds__pk PRIMARY KEY ( start_datetime, end_datetime ),
CONSTRAINT table_name_insert_bounds__chk CHECK ( start_datetime <= end_datetime )
);
And a package containing your stored procedures:
CREATE PACKAGE data_owner.table_name_management_pkg IS
PROCEDURE add_value(
i_datetime IN TABLE_NAME.DATETIME%TYPE,
i_value IN TABLE_NAME.VALUE%TYPE
);
END;
/
CREATE PACKAGE BODY data_owner.table_name_management_pkg IS
PROCEDURE add_value(
i_datetime IN TABLE_NAME.DATETIME%TYPE,
i_value IN TABLE_NAME.VALUE%TYPE
)
IS
valid_datetime NUMBER;
BEGIN
SELECT CASE
WHEN EXISTS(
SELECT 1
FROM table_name_insert_bounds
WHERE i_datetime BETWEEN start_datetime AND end_datetime
)
THEN 1
ELSE 0
END
INTO valid_datetime
FROM DUAL;
IF valid_datetime = 0 THEN
RAISE_APPLICATION_ERROR(
-20000,
'Date-time is outside of current insertion range.'
);
END IF;
INSERT INTO table_name ( datetime, value )
VALUES ( i_datetime, i_value );
END;
END;
/
And then grant permissions to the end user:
GRANT SELECT ON data_owner.table_name TO end_user;
GRANT EXECUTE ON data_owner.table_name_management_pkg TO end_user;
Then the end user can only perform DML actions via the stored procedure in the package (they have no permissions to perform DML directly on the table bypassing the procedure) but could also SELECT all the data and the data owner can set the date bounds which the end user is able to insert within (and the end user cannot modify these bounds).
For example:
If the data owner sets these boundaries:
INSERT INTO table_name_insert_bounds ( start_datetime, end_datetime )
VALUES ( DATE '2020-01-01', DATE '2020-02-01' );
Then the end user can run:
BEGIN
data_owner.table_name_management_pkg.ADD_VALUE( DATE '2020-01-10', 42 );
END;
/
and one row will be inserted but if they try to:
BEGIN
data_owner.table_name_management_pkg.ADD_VALUE( DATE '2020-02-02', 13 );
END;
/
Then will get the exception:
ORA-20000: Date-time is outside of current insertion range.
db<>fiddle here