mysql command not found in docker bash shell script - mysql

Question

I have a shell script that copies a .sql script to a docker container and executes it.
When I execute the line:
docker exec -it $existingMySQLContainer bash -c '"mysql -u root -proot < setup_db.sql"'
on my host machine outside of the script, it works. But when I execute it from within the script, I get:
bash: mysql -u root -proot < setup_db.sql: command not found
Why doesn't this work within the script?
Script:
#!/bin/sh
# check to see if the container with the name exists.
existingMySQLContainer=$(docker ps -a -q -f name="local-test-mysql-db")
if [ ! -z "$existingMySQLContainer" ]
then
# conatiner has been found so tear it down for a clean database
echo "Found existing local test db " $existingMySQLContainer
docker rm -f $existingMySQLContainer
fi
docker run --name local-test-mysql-db -d -p 3310:3306 -e MYSQL_ROOT_PASSWORD=root mysql:8
# run the docker container
existingMySQLContainer=$(docker ps -a -q -f name="local-test-mysql-db")
docker cp setup_db.sql $existingMySQLContainer:/setup_db.sql
docker exec -it $existingMySQLContainer bash -c '"mysql -u root -proot < setup_db.sql"'
I tried arranging the double quotes in various ways and no success.
Removing the doubles quotes to give just
Removing doubles quotes so the last line is:
ocker exec -it $existingMySQLContainer bash -c '"mysql -u root -proot < setup_db.sql"'
gives:
bash: mysql -u root -proot < setup_db.sql: command not found
SOLUTION
Docker MySQL just hadn't finished loading yet. I was trying to access it before it had finished loading.