How to create users from list in oracle? - sql

Question

I'm trying to create users with the prefix sit from a list of the greek alphabet. Like sit-alpha, sit-beta, so on.
This is what I have so far:
BEGIN
LIST:= 'alpha, beta, gamma';
FOR u IN LIST
LOOP
EXECUTE IMMEDIATE 'CREATE USER SIT-' || TO_CHAR (U)||' IDENTIFIED BY
CLERK'||TO_CHAR (U) ;
EXECUTE IMMEDIATE 'GRANT CONNECT, RESOURCE TO SIT-'||TO_CHAR(U);
END LOOP;
END;
But it says "PLS-00201: identifier 'LIST' must be declared". How do I do this properly?

Answer 1

Your code is mostly correct. However, you need to split the comma-separated list of values into an array using the REGEXP_SUBSTR function to loop through each element in the list. About the error "PLS-00201: identifier 'LIST' must be declared" means that the LIST variable you used in your code is not declared. This error usually occurs when a variable has not been declared or initialized correctly. In your code, you must declare the LIST variable before using it. You can do this by using the DECLARE command at the beginning of your code, like this:
DECLARE
LIST VARCHAR2(200) := 'alpha, beta, gamma';
BEGIN
FOR u IN (SELECT trim(regexp_substr(LIST, '[^,]+', 1, LEVEL)) AS val FROM dual
CONNECT BY LEVEL <= regexp_count(LIST, ',') + 1)
LOOP
EXECUTE IMMEDIATE 'CREATE USER SIT-' || u.val || ' IDENTIFIED BY CLERK' || u.val;
EXECUTE IMMEDIATE 'GRANT CONNECT, RESOURCE TO SIT-' || u.val;
END LOOP;
END;
Here's a great explanation of my code :
The first line of the code is a DECLARE command that indicates the beginning of a variable declaration section. This section declares all the variables and constants that will be used in the rest of the code.
The second line declares a LIST variable of type VARCHAR2 with a maximum length of 200 characters. This variable contains a comma-separated list of the user names you wish to create.
The third line is the BEGIN command that indicates the start of the executable code block.
The fourth line begins a FOR loop that traverses each item in the list of usernames using a SELECT query.
The SELECT query uses the regexp_substr function to retrieve each comma-separated item in the list and returns it as a val. The trim function is used to remove any unnecessary spaces that may be present around each element in the list. The CONNECT BY clause is used to generate the rows necessary for the FOR loop to traverse each element in the list.
The FOR loop uses the variable u to store each element in the list at each iteration.
The two EXECUTE IMMEDIATE commands inside the FOR loop create a new user using the username SIT- followed by the value of val, and then add CONNECT and RESOURCE privileges to that user.
Finally, the last line of code is the END command which indicates the end of the executable code block.
In summary, this code extracts each item from the list of user names, creates a new user with a name that includes that item, and then adds CONNECT and RESOURCE privileges to that user. This code uses Oracle functions to extract each item from the list and dynamically create the users.