Inserting data into table with select - sql

Question

i`m trying to do something.... I have to insert some data in to a table but..... So here is where I end up...
INSERT into HR.my_employees
(ID,LAST_NAME,FIRST_NAME,userid,SALARY)
SELECT
3 AS ID,
'Biri' AS LAST_NAME,
'Ben' AS FIRST_NAME,
substr(FIRST_NAME,1,1)||''||substr(LAST_NAME,1,7) AS userid,
1100 AS salary
FROM dual
UNION
SELECT
4 AS ID,
'Newman' AS LAST_NAME,
'Chad' AS FIRST_NAME,
substr(FIRST_NAME,1,1)||''||substr(LAST_NAME,1,7) AS userid,
750 AS salary
FROM dual;
any suggestion...

Answer 1

You cannot refer to an alias in the SELECT or WHERE clauses of a sub-query where it is defined. Generate the data in a sub-query (or a sub-query factoring clause) and then refer to it in an outer query:
INSERT into HR.my_employees(ID,LAST_NAME,FIRST_NAME,userid,SALARY)
WITH data (id, last_name, first_name, salary) AS (
SELECT 3, 'Biri', 'Ben', 1100 FROM DUAL UNION ALL
SELECT 4, 'Newman', 'Chad', 750 FROM DUAL
)
SELECT id,
last_name,
first_name,
SUBSTR(first_name,1,1) || SUBSTR(last_name,1,7),
salary
FROM data;
or:
INSERT into HR.my_employees(ID,LAST_NAME,FIRST_NAME,userid,SALARY)
SELECT id,
last_name,
first_name,
SUBSTR(first_name,1,1) || SUBSTR(last_name,1,7),
salary
FROM (
SELECT 3 AS id, 'Biri' AS last_name, 'Ben' AS first_name, 1100 AS salary FROM DUAL
UNION ALL
SELECT 4, 'Newman', 'Chad', 750 FROM DUAL
);
fiddle

Answer 2

Why do you want to use select statements? - Based on the values you provide it seems like you want to insert hardcoded values. Or does the dual table contain data you want to insert into HR.my_employees?
If you want to just insert values into the table, but not from an existing one, you can use the following structure:
INSERT INTO table_name (column1, column2, column3, ..., columnXX)
VALUES (value1, value2, value3, ..., valueXX);