CREATE TABLE IF NOT EXISTS bar (
bar_id INT UNSIGNED NOT NULL AUTO_INCREMENT,
bar_name VARCHAR(255),
PRIMARY KEY (bar_id),
UNIQUE KEY bar_name (bar_name)
) ENGINE = INNODB;

CREATE TABLE IF NOT EXISTS foo (
foo_id INT UNSIGNED NOT NULL AUTO_INCREMENT,
foo_name VARCHAR(255),
bar_id INT UNSIGNED NOT NULL,
PRIMARY KEY (foo_id),
UNIQUE KEY foo_name (foo_name),
CONSTRAINT fk_bar_id FOREIGN KEY (bar_id) REFERENCES bar (bar_id)
) ENGINE = INNODB;

INSERT INTO bar VALUES (1,'a'),(2,'b'),(3,'c');
INSERT INTO foo VALUE (1,'qwe',1),(2,'asd',1),(3,'zxc',2),(4,'rty',2),(5,'dfg',3);

SELECT f.foo_id,f.foo_name,b.bar_id,b.bar_name FROM foo f JOIN bar b ON f.bar_id=b.bar_id;

+--------+----------+--------+----------+
| foo_id | foo_name | bar_id | bar_name |
+--------+----------+--------+----------+
|      1 | qwe      |      1 | a        |
|      2 | asd      |      1 | a        |
|      3 | zxc      |      2 | b        |
|      4 | rty      |      2 | b        |
|      5 | dfg      |      3 | c        |
+--------+----------+--------+----------+

CREATE TEMPORARY TABLE IF NOT EXISTS tmp_foo (
foo_name VARCHAR(255),
bar_name VARCHAR(255)
);

INSERT INTO tmp_foo VALUES ('qwe','a'),('asd','b'),('zxc','b'),('rty','d'),('dfg','d'),('cvb','a'),('uio','e');

SELECT * FROM tmp_foo;

+----------+----------+
| foo_name | bar_name |
+----------+----------+
| qwe      | a        |
| asd      | b        |
| zxc      | b        |
| rty      | d        |
| dfg      | d        |
| cvb      | a        |
| uio      | e        |
+----------+----------+

INSERT IGNORE INTO bar (bar_name) 
SELECT bar_name FROM tmp_foo;

INSERT IGNORE INTO foo (foo_name,bar_id)
SELECT t.foo_name, b.bar_id FROM tmp_foo t JOIN bar b ON b.bar_name=t.bar_name
ON DUPLICATE KEY UPDATE bar_id=b.bar_id;

SELECT f.foo_id,f.foo_name,b.bar_id,b.bar_name FROM foo f JOIN bar b ON f.bar_id=b.bar_id;

+--------+----------+--------+----------+
| foo_id | foo_name | bar_id | bar_name |
+--------+----------+--------+----------+
|      1 | qwe      |      1 | a        |
|      6 | cvb      |      1 | a        |
|      2 | asd      |      2 | b        |
|      3 | zxc      |      2 | b        |
|      4 | rty      |      4 | d        |
|      5 | dfg      |      4 | d        |
|      7 | uio      |      5 | e        |
+--------+----------+--------+----------+