mysql copy many records with one change - mysql

Question

Here is a table Evact:
+--------------+-----------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+--------------+-----------------------+------+-----+---------+-------+
| EvActMas | char(10) | NO | PRI | | |
| EvActSub | char(10) | NO | PRI | | |
| EvActCode | char(10) | NO | PRI | | |
| EvActIncOutg | enum('I','O','B','N') | YES | | NULL | |
| EvActBudAct | enum('B','A','O') | YES | | NULL | |
...other columns ...
and here are some records:
EvActMas EvActSub EvActCode EvActIncOutg EvActBudAct ..other..
Bank-2017 Incoming mth01 I A
Bank-2017 Incoming mth02 I A
Bank-2017 Incoming mth03 I A
Bank-2017 Incoming mth04 I A
Bank-2017 Incoming mth05 I A
Bank-2017 Incoming mth06 I A
I want to add six new records to the table where 'Incoming' is changed to 'Outgoing' and 'I' is changed to 'O'.
I did it the hard way by creating a new table from the old one; updating the new table and then inserting back into Evact:
Create table btemp like Evact;
update btemp set Evact = 'Outgoing', EvActIncOutg = 'O';
insert into Evact select * from btemp;
That worked, but I want to get better at SQL. What I wish for is a way to do this in one step by joining Evact to itself in some way. Does anyone have a suggestion?

Answer 1

If you want to insert a bunch of rows that are part copies of existing rows:
INSERT INTO evact
SELECT evactmas, 'Outgoing', evactcode, 'O', evactbudact, ...other..
FROM evact
You make a Select statement that is the data you want to insert, some columns in the select are the values as-is, other columns are the new values
If you aren't specifying all the columns in the select you'll have to put a list of column names in brackets after the INTO so MySQL knows which columns are to get what data. You can only omit the columns list if your select query selects the same number of columns in the table (in which case the columns selected must be in the same order as the table columns to be inserted into)
If your table has a calculated primary key (auto increment for example) specify the value to insert as 0 or NULL to have MySQL calculate a new value for it, or name all the columns except that one after the INTO and omit it from the select list