How can new docker image have dependent child images - image

Question

I am new to Docker and want to understand image management better. A new image that I just created using
docker image build -t jefe/mh_db:v.1.1.0 ./
When I try to delete using
docker image rm d4c0c9225252
where d4c0c9225252 is the Image ID, returns
Error response from daemon: conflict: unable to delete d4c0c9225252 (cannot be forced) - image has dependent child images
Yes it's related to other posts regarding cannot delete. But I want to understand why a dependency exists.
How can this child image have images that are dependent upon it? I literally just created it
The dockerfile that is used in building the image
FROM mysql:5.7.27
MAINTAINER jefe
# Specify ports
EXPOSE 3306
Update
docker image ls | grep d4c0c9225252
jefe/mh_db v.1.1.0 d4c0c9225252 2 hours ago 373MB
Additionally
docker inspect d4c0c9225252
[
{
"Id": "sha256:d4c0c922525201d62e49ac73d03e27653e77e2ac5e3f11334a7a09d7c6d977fe",
"RepoTags": [
"jefe/mh_db:v.1.1.0"
],
"RepoDigests": [],
"Parent": "sha256:b0fead29523e498fd0f990abcc2b2bbb46952ad3361fbebcc304e31be69bd840",
"Comment": "",
"Created": "2019-08-08T15:24:57.324861036Z",
"Container": "6abc71375823faeb4819720a09ae348b0da4d9ae213c167c3911ca706d7c8b92",
"ContainerConfig": {
"Hostname": "6abc71375823",
"Domainname": "",
"User": "",
"AttachStdin": false,
"AttachStdout": false,
"AttachStderr": false,
"ExposedPorts": {
"3306/tcp": {},
"33060/tcp": {}
},
"Tty": false,
"OpenStdin": false,
"StdinOnce": false,
"Env": [
"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
"GOSU_VERSION=1.7",
"MYSQL_MAJOR=5.7",
"MYSQL_VERSION=5.7.27-1debian9"
],
"Cmd": [
"/bin/sh",
"-c",
"#(nop) ",
"EXPOSE 3306"
],
"ArgsEscaped": true,
"Image": "sha256:b0fead29523e498fd0f990abcc2b2bbb46952ad3361fbebcc304e31be69bd840",
"Volumes": {
"/var/lib/mysql": {}
},
"WorkingDir": "",
"Entrypoint": [
"docker-entrypoint.sh"
],
"OnBuild": null,
"Labels": {}
},
"DockerVersion": "19.03.1",
"Author": "jefe",
"Config": {
"Hostname": "",
"Domainname": "",
"User": "",
"AttachStdin": false,
"AttachStdout": false,
"AttachStderr": false,
"ExposedPorts": {
"3306/tcp": {},
"33060/tcp": {}
},
"Tty": false,
"OpenStdin": false,
"StdinOnce": false,
"Env": [
"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
"GOSU_VERSION=1.7",
"MYSQL_MAJOR=5.7",
"MYSQL_VERSION=5.7.27-1debian9"
],
"Cmd": [
"mysqld"
],
"ArgsEscaped": true,
"Image": "sha256:b0fead29523e498fd0f990abcc2b2bbb46952ad3361fbebcc304e31be69bd840",
"Volumes": {
"/var/lib/mysql": {}
},
"WorkingDir": "",
"Entrypoint": [
"docker-entrypoint.sh"
],
"OnBuild": null,
"Labels": null
},
"Architecture": "amd64",
"Os": "linux",
"Size": 373273403,
"VirtualSize": 373273403,
"GraphDriver": {
"Data": {
"LowerDir": "/var/lib/docker/overlay2/11891a42dc63fb6851e3fb12a1dd7e7285d18df83ecfd1f5aa40e44466921c58/diff:/var/lib/docker/overlay2/e0c695335789cba5a8e6524804bd1c2d1836db16650105e6863e7023bc289753/diff:/var/lib/docker/overlay2/2b4e10627f78a0185f8975b62b954a14e79fc6fb71a3caae07180e8e00f51b44/diff:/var/lib/docker/overlay2/f9dd057675e39a3eab99143f07bcb7df8a44eba5d1f1d15e567471a7c3a9e491/diff:/var/lib/docker/overlay2/c28612d7a8d1b187ddb7fc995c5fe733e0c18def13df798f1de5af2bdac9d3f4/diff:/var/lib/docker/overlay2/f8e41886d7ae8d8939ae2dc11b4ff941ef931aa18bc2f8cb0f724cc9e270ab3c/diff:/var/lib/docker/overlay2/8796390ee625b42b56d7822d128cc50bf88fbfd1f7f5ac9e7ecda9e721944946/diff:/var/lib/docker/overlay2/86552fa54367c794979383dbba257f1292f2a137dae0304d1eb036ba2249bc7b/diff:/var/lib/docker/overlay2/168353bdf70d8140026c2cf58da64eee7409f710832be601dad3e0cc6a02c01a/diff:/var/lib/docker/overlay2/ac908915344e5f65df6e0121f77bd48fdaa822974317cdb83a59f0618893ddb2/diff",
"MergedDir": "/var/lib/docker/overlay2/1826972009d9ce18265129a2d4928b708bf6780370530e4c1be8b1efd096b2cd/merged",
"UpperDir": "/var/lib/docker/overlay2/1826972009d9ce18265129a2d4928b708bf6780370530e4c1be8b1efd096b2cd/diff",
"WorkDir": "/var/lib/docker/overlay2/1826972009d9ce18265129a2d4928b708bf6780370530e4c1be8b1efd096b2cd/work"
},
"Name": "overlay2"
},
"RootFS": {
"Type": "layers",
"Layers": [
"sha256:d56055da3352f918f4d8a42350385ea5b10d0906e746a8fbb4b850f9284deee5",
"sha256:b78ec9586b345b0efdb0297261c0044652563045a28a7cc6d27dd314eda1e0eb",
"sha256:c6926fcee1912ebb41215a70b1d0ed77e3b8db38cfe69b936d18b346096e144c",
"sha256:007a7f930352c0fd98663021fb1ee08768462eb5bc9045342da9e9f73fd79a7f",
"sha256:2f1b41b24201f4ae635819b1d7717ab04c000f04e7708de3bb012a60d3ef630b",
"sha256:77737de99484a6e2e2ae4bea0cf7ec4d3063827a6dd49a243694ef00929350d2",
"sha256:7e7fffcdabb3e0655bf46756dd04018ce051f81fbaba8bff3703ac987def88be",
"sha256:83bba64580292cc5af1fd3cabb74b18c143e05cd45d882c9e09edc8ff79a1119",
"sha256:94f63a189eef2bdb32668faa0ce08dc5da01eccb91ad548f28052048e810e5f8",
"sha256:0c3e10ddbe75e0a4efcee6aa06716b651227ceb358e78922b9fe9ea7f5a63992",
"sha256:5572431ce4dea5defe6a0d0586ad3b25a74d59bfbbb05c2a257c5d71a27eba4c"
]
},
"Metadata": {
"LastTagTime": "2019-08-08T15:24:57.393863976Z"
}
}

Answer 1

Docker wont let you delete an image if you have more than one tag on it. To find out the tags you can filter the output of docker image ls
docker image ls | grep d4c0c9225252