Loop trough a fixed list of values - oracle

Question

I have a list of tables that needs to be renamed before each data migration.
I came up with the procedure below to check if the table exists and eventually rename it, appending its creation date:
DECLARE
v_cnt PLS_INTEGER;
v_date varchar2(50);
v_table varchar2(50);
v_table_short varchar2(50);
BEGIN
v_table:='MT_TABLE_1';
v_table_short:=SUBSTR(v_table,8);
SELECT COUNT(*)
INTO v_cnt
FROM dba_tables
WHERE owner = 'OWNER'
AND table_name = v_table;
IF(v_cnt > 0) THEN
select CREATED into v_date FROM DBA_OBJECTS WHERE OBJECT_TYPE = 'TABLE' AND OBJECT_NAME=v_table;
execute immediate 'rename "'||v_table||'" to "'||v_table_short||'_'||v_date||'"';
END IF;
v_table:='MY_TABLE_2';
v_table_short:=SUBSTR(v_table,8);
SELECT COUNT(*)
INTO v_cnt
FROM dba_tables
WHERE owner = 'OWNER'
AND table_name = v_table;
IF(v_cnt > 0) THEN
select CREATED into v_date FROM DBA_OBJECTS WHERE OBJECT_TYPE = 'TABLE' AND OBJECT_NAME=v_table;
execute immediate 'rename "'||v_table||'" to "'||v_table_short||'_'||v_date||'"';
END IF;
END;
/
Now I want to avoid defining the v_table variable manually and repeating the code for each of the objects that I need to check for: is there a way to insert them as a list in a table variable or so, and have the code loop for each of the values there?
Thank you.

Answer 1

Yes, I like #Srinika's idea. Something like that:
CREATE TABLE table_list (
sort_order NUMBER UNIQUE,
long_name VARCHAR2(128 BYTE) PRIMARY KEY,
short_name VARCHAR2(128 BYTE) UNIQUE
);
INSERT INTO table_list VALUES (1,'MY_TABLE_1','MYTAB1');
INSERT INTO table_list VALUES (2,'MY_TABLE_2','MYTAB2');
I've added a column for the short name instead of computing it on the fly, as two tables might have the same first 8 characters in the name. The short_name needs to be unique else two tables will end up with the same short name. The sort order is only to do the renaming in the same order every time.
CREATE OR REPLACE PROCEDURE rename_tables AS
v_date VARCHAR2(8);
v_short_name VARCHAR2(128);
v_stmt VARCHAR2(200);
BEGIN
v_date := TO_CHAR(SYSDATE, 'YYYYMMDD');
FOR r IN (SELECT * FROM table_list ORDER BY sort_order) LOOP
v_short_name := r.short_name || '_' || v_date;
v_stmt := 'rename '||r.long_name||' to '||v_short_name;
DBMS_OUTPUT.PUT_LINE(v_stmt);
EXECUTE IMMEDIATE v_stmt;
END LOOP;
END rename_tables;
/
Calling this procedure would produce the output:
rename MY_TABLE_1 to MYTAB1_20200330
rename MY_TABLE_2 to MYTAB2_20200330
You'll need to add checks if the long table exists, and whether a renamed table is already there. I'd log the statements to a log table, too.
Regarding ": I would use them only if you have mixed case table names in the database.