Resolve "Upsert Channels data into database"

Closes #23 (closed)

alembic/versions/2023_06_05_1553-65e724d33af6_in_our_case_channel_codes_must_be_.py

+"""in our case, channel codes must be unique for each station
+
+Revision ID: 65e724d33af6
+Revises: 64b801005ea8
+Create Date: 2023-06-05 15:53:56.884881
+
+"""
+import sqlalchemy as sa
+
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision = "65e724d33af6"
+down_revision = "64b801005ea8"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.create_unique_constraint(
+        op.f("uq_channel_code"), "channel", ["code", "station_id"]
+    )
+    # ### end Alembic commands ###
+
+
+def downgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_constraint(op.f("uq_channel_code"), "channel", type_="unique")
+    # ### end Alembic commands ###