Passing column name as parameter in Oracle PL_SQL function - sql

Question

I am trying to pass two input parameters, column name and table name . Then the function should output a string value as defined below :
create or replace function get_id5(in_col_name IN VARCHAR2,in_tbl_name IN VARCHAR2)
return VARCHAR2
is
/*in_col_nm varchar(32) := in_col_name;
/*in_tbl_nm varchar(64) := in_tbl_name; */
integer_part NUMBER ;
integer_part_str VARCHAR2(32) ;
string_part VARCHAR2(32) ;
full_id VARCHAR2(32) ;
out_id VARCHAR(32) ;
BEGIN
/*select MAX(in_col_nm) INTO full_id FROM in_tbl_nm ; */
execute immediate 'select MAX('||in_col_name||') FROM' || in_tbl_name ||'INTO' || full_id;
/*select regexp_replace(full_id , '[^0-9]', '') INTO integer_part_str , regexp_replace(full_id , '[^a-z and ^A-Z]', '') INTO string_part from dual ; */
integer_part_str := regexp_replace(full_id , '[^0-9]', '') ;
string_part := regexp_replace(full_id , '[^a-z and ^A-Z]', '') ;
integer_part := TO_NUMBER(integer_part_str);
integer_part := integer_part + 1 ;
integer_part_str := TO_CHAR(integer_part) ;
out_id := string_part + integer_part_str ;
return out_id;
END;
I have a table named BRANDS in Database and the max value for column BRAND_ID is 'Brand05'. The expected output is 'Brand06'.
However when i run:
select get_id5('BRAND_ID' , 'BRANDS') from dual;
or
DECLARE
a VARCHAR(32) ;
BEGIN
a := get_id5('BRAND_ID' , 'BRANDS');
END;
I am getting the below error:
ORA-00923: FROM keyword not found where expected

Answer 1

You need spaces between the FROM and the table_name and the INTO should be outside of the SQL text:
execute immediate 'select MAX('||in_col_name||') FROM ' || in_tbl_name INTO full_id;
You could also use DBMS_ASSERT:
execute immediate 'select MAX('||DBMS_ASSERT.SIMPLE_SQL_NAME(in_col_name)||') FROM ' || DBMS_ASSERT.SIMPLE_SQL_NAME(in_tbl_name) INTO full_id;
Then you need to use || as the string concatenation operator (rather than +).
Your function could be:
create or replace function get_id5(
in_col_name IN VARCHAR2,
in_tbl_name IN VARCHAR2
) RETURN VARCHAR2
IS
full_id VARCHAR2(32);
BEGIN
execute immediate 'select MAX('||DBMS_ASSERT.SIMPLE_SQL_NAME(in_col_name)||') '
|| 'FROM ' || DBMS_ASSERT.SIMPLE_SQL_NAME(in_tbl_name)
INTO full_id;
return regexp_replace(full_id , '\d+', '')
|| TO_CHAR(regexp_replace(full_id , '\D+', '') + 1);
END;
/
For the sample data:
CREATE TABLE brands (brand_id) AS
SELECT 'BRAND5' FROM DUAL;
Then:
select get_id5('BRAND_ID' , 'BRANDS') AS id from dual;
Outputs:
ID
BRAND6
db<>fiddle here
A better solution
To generate the number, use a SEQUENCE or, from Oracle 12, an IDENTITY column and, if you must have a string prefix then use a virtual column to generate it.
CREATE TABLE brands(
ID NUMBER
GENERATED ALWAYS AS IDENTITY
PRIMARY KEY,
brand_id VARCHAR2(10)
GENERATED ALWAYS
AS (CAST('BRAND' || TO_CHAR(id, 'FM000') AS VARCHAR2(10)))
);
BEGIN
INSERT INTO brands (id) VALUES (DEFAULT);
INSERT INTO brands (id) VALUES (DEFAULT);
INSERT INTO brands (id) VALUES (DEFAULT);
END;
/
SELECT * FROM brands;
Outputs:
ID
BRAND_ID
1
BRAND001
2
BRAND002
3
BRAND003
db<>fiddle here